Links in Laser projector thread
http://pyanczer.home.mindspring.com/Tour/mhalytrb.html
http://pyanczer.home.mindspring.com/Tour/mirscrws.html
http://pyanczer.home.mindspring.com/Tour/vibrscan.html
http://pyanczer.home.mindspring.com/Tour/scophony.html
http://pyanczer.home.mindspring.com/Tour/eidophor.html
http://deinterlace.sourceforge.net/downloads.htm
www.gebrauchtlaser.de/gebrauch/d2-z.htm
www.laserfaq.com
www.schneider-ag.de
www.k3pgp.org
www.rfe-online.de/_archiv/05/tipps/22.htm
http://home.t-online.de/home/j.redelfs/sync.htm
www.eopc.com/scanners.html
http://pyanczer.home.mindspring.com/Tour/mhalytrb.html
http://pyanczer.home.mindspring.com/Tour/mirscrws.html
http://pyanczer.home.mindspring.com/Tour/vibrscan.html
http://pyanczer.home.mindspring.com/Tour/scophony.html
http://pyanczer.home.mindspring.com/Tour/eidophor.html
http://deinterlace.sourceforge.net/downloads.htm
www.gebrauchtlaser.de/gebrauch/d2-z.htm
www.laserfaq.com
www.schneider-ag.de
www.k3pgp.org
www.rfe-online.de/_archiv/05/tipps/22.htm
http://home.t-online.de/home/j.redelfs/sync.htm
www.eopc.com/scanners.html
Ok I have my LCD projector running quite well. It is a projection panel you can see them for sale at Ebay auction. Search engine. ebay. ebay search "projection panel" and you should see 20 or so panels for sale. Anyway I have a panel. I have an overhead projector and I have a 52 inch wide picture on a slide projector screen. Picture is not too bad. The reason I desperately needed a big TV is to watch the World Cup soccer which is absolutely fantastic on a large screen. There is a thread listing goodpanel/bad panel which is people's experience with different LCD panels. If you are going to buy from Ebay take care because quite a few panels sound good but are not suitable for video.
While getting my panel and getting it going I have also been thinking about getting more light for the laser projector. It is still a small scale investigation ie I am not going to spend much money on it but there are three considerations
1 scanning the beam
2 getting the beam in the first place
3 modulating the beam(s)
Because scanning the beam at an affordable price was in my opinion the hardest of the lot I worked on that first because if that could not be done economically there was no point with the rest. I spent nearly 5 months trying out different ways to scan the beam cheaply and I am pretty sure it can be done at low cost by using a polygon motor with 8 facet mirror and 39 small stationary mirrors. Now I have nearly caught up on 5 months work not done like painting the house and finishing a glass house and my current project a log splitter for firewood I can give some time to item 2 getting the beam. Sorry no lasers. At present they are just too expensive so an alternative similar to a laser needs to be found.
All modern small high power video projectors use a white light source and divide it up into red green and blue. They pass the 3 colours through 3 small LCD units then combine the light into one beam and send it off through a projection lens to the screen. Sounds allright but lets look at that in detail. Light source is a very short arc lamp. Expensive. Colour splitting by a dichroic prism very expensive. recombining red green and blue into composite beam by dichroic prism very expensive. So far one expensive item and two very expensive items. Not good for DIY people. Modern video projectors dont need light that simulates a laser either so thats one more problem we have.
We need a powerful light source that can be collected by a reflector and collimated into a beam about 2 mm in diameter and which has good light uniformaty in its crossection. If we had such a light source we might be able to split it into red green and blue components and be half way there. Its a law of optics that if you start off with a large area light source you cannot turn it into a small area light source without loosing most of the light. So we really need a short arc lamp that has red green and blue components and is cheap. Unfortunately when you say short arc lamp you are talking about an expensive lamp around $800- $1000 US. Powerful lights and associated reflectors have been under intense study in the last five -ten years. The two go hand in hand. To collect light efficiently from a light you need a good reflector. To utilise a good reflector properly you need a light with a very short arc lenght around 1-2 mm. These very efficient lights and reflectors are avaliable but as mentioned are expensive. The limiting problem is if the arc lenght is not as short as possible, the reflector will only be able to collect that light that is exectly at the reflector focus. High output lights with arc lengths of 5-10mm are redily avaliable in the range of $100 - 200 US. Many thousand are used by people with aquariums for providing daylight lighting. They are used for high power torches for growing plants for medical inspection of patients and many other uses. For us the arc lenght is too long and we would not get sufficient light to be useful. As mentioned many people have studied this problem of getting the most from a light because getting by with a cheaper light can turn a project from not viable into success.
There are several ways to go to get the absolute most from a light source. The obvious one is to buy a light with a very short arc and a very accurate reflector. Thats a money solution and is used often. Buy the best avaliable and get on with other things. Other ways to look are shape of the reflector and possible ways to use less than ideal light sources. Digging through the US patent data base I found that even in the 1930's this problem was well known because in those days they did not have modern short arc lamps. They had lamps with long arcs and even exposed carbon arcs for light sources so many in the field paid special attention to reflectors to gather as much light as possible. Two things I found. One is the reflector shape is important and second the reflectivity of the reflector was also very important. The reflectivity seems straight forward. The better a reflector reflects, the more light you will get. But the shape of the reflector showed up several interesting results.
Take a parabolic reflector. Place a light source at the focus and you get parallel light rays. Should be allright. Used all the time in torches and lights for stages and headlights on cars and many others. First problem is there is hole in the reflector where you insert the light so that part does not reflect. Second most people know by now that you need a point source light or else you only get the part of the light at the very focus that goes where it is needed. The rest of the light is generally in the right direction but is neither parallel nor useful. Also you get light from the front of the light going forward but not parallel. This problem is usually reduced by painting the front of the lamp black so it does not radiate, or placing a metal reflector in front to reflect the forward light back into the main reflector.
Reflectors do make a big difference. You can test this yourself by unscrewing your torch, removing the reflector and just having the bare bulb illuminating. You get a small amount of light going in all directions but none going forward as a useful beam. Without suitable reflectors car headlights would not be able to give safe night driving. We need reflectors but can we find a reflector that overcomes some of the deficiencies and allows more useful light to come forward in a controlled manner. Surprisingly the answer is yes. There are better reflectors. I do not wish to minimise this problem. There are better reflectors but they are harder to make than regular reflectors and they are considered only because it costs a lot of money to buy a short arc light and a quality factory made reflector.
We need a reflector light combination that is cheap and effective. The light has to come to a point because then it can be collimated into a parallel beam in the range of 2 mm diameter. Several posts ago I mentioned a type of reflector called an orthogonal parabolic refllector which is supposed to give a razor sharp point from a long light source. This reflector is not a parabolic reflector. It is actually an elliptical reflector in that the point is at focus position number 2 but thats what it is called. I will look into it and see if it is useful for a laser projector.
While getting my panel and getting it going I have also been thinking about getting more light for the laser projector. It is still a small scale investigation ie I am not going to spend much money on it but there are three considerations
1 scanning the beam
2 getting the beam in the first place
3 modulating the beam(s)
Because scanning the beam at an affordable price was in my opinion the hardest of the lot I worked on that first because if that could not be done economically there was no point with the rest. I spent nearly 5 months trying out different ways to scan the beam cheaply and I am pretty sure it can be done at low cost by using a polygon motor with 8 facet mirror and 39 small stationary mirrors. Now I have nearly caught up on 5 months work not done like painting the house and finishing a glass house and my current project a log splitter for firewood I can give some time to item 2 getting the beam. Sorry no lasers. At present they are just too expensive so an alternative similar to a laser needs to be found.
All modern small high power video projectors use a white light source and divide it up into red green and blue. They pass the 3 colours through 3 small LCD units then combine the light into one beam and send it off through a projection lens to the screen. Sounds allright but lets look at that in detail. Light source is a very short arc lamp. Expensive. Colour splitting by a dichroic prism very expensive. recombining red green and blue into composite beam by dichroic prism very expensive. So far one expensive item and two very expensive items. Not good for DIY people. Modern video projectors dont need light that simulates a laser either so thats one more problem we have.
We need a powerful light source that can be collected by a reflector and collimated into a beam about 2 mm in diameter and which has good light uniformaty in its crossection. If we had such a light source we might be able to split it into red green and blue components and be half way there. Its a law of optics that if you start off with a large area light source you cannot turn it into a small area light source without loosing most of the light. So we really need a short arc lamp that has red green and blue components and is cheap. Unfortunately when you say short arc lamp you are talking about an expensive lamp around $800- $1000 US. Powerful lights and associated reflectors have been under intense study in the last five -ten years. The two go hand in hand. To collect light efficiently from a light you need a good reflector. To utilise a good reflector properly you need a light with a very short arc lenght around 1-2 mm. These very efficient lights and reflectors are avaliable but as mentioned are expensive. The limiting problem is if the arc lenght is not as short as possible, the reflector will only be able to collect that light that is exectly at the reflector focus. High output lights with arc lengths of 5-10mm are redily avaliable in the range of $100 - 200 US. Many thousand are used by people with aquariums for providing daylight lighting. They are used for high power torches for growing plants for medical inspection of patients and many other uses. For us the arc lenght is too long and we would not get sufficient light to be useful. As mentioned many people have studied this problem of getting the most from a light because getting by with a cheaper light can turn a project from not viable into success.
There are several ways to go to get the absolute most from a light source. The obvious one is to buy a light with a very short arc and a very accurate reflector. Thats a money solution and is used often. Buy the best avaliable and get on with other things. Other ways to look are shape of the reflector and possible ways to use less than ideal light sources. Digging through the US patent data base I found that even in the 1930's this problem was well known because in those days they did not have modern short arc lamps. They had lamps with long arcs and even exposed carbon arcs for light sources so many in the field paid special attention to reflectors to gather as much light as possible. Two things I found. One is the reflector shape is important and second the reflectivity of the reflector was also very important. The reflectivity seems straight forward. The better a reflector reflects, the more light you will get. But the shape of the reflector showed up several interesting results.
Take a parabolic reflector. Place a light source at the focus and you get parallel light rays. Should be allright. Used all the time in torches and lights for stages and headlights on cars and many others. First problem is there is hole in the reflector where you insert the light so that part does not reflect. Second most people know by now that you need a point source light or else you only get the part of the light at the very focus that goes where it is needed. The rest of the light is generally in the right direction but is neither parallel nor useful. Also you get light from the front of the light going forward but not parallel. This problem is usually reduced by painting the front of the lamp black so it does not radiate, or placing a metal reflector in front to reflect the forward light back into the main reflector.
Reflectors do make a big difference. You can test this yourself by unscrewing your torch, removing the reflector and just having the bare bulb illuminating. You get a small amount of light going in all directions but none going forward as a useful beam. Without suitable reflectors car headlights would not be able to give safe night driving. We need reflectors but can we find a reflector that overcomes some of the deficiencies and allows more useful light to come forward in a controlled manner. Surprisingly the answer is yes. There are better reflectors. I do not wish to minimise this problem. There are better reflectors but they are harder to make than regular reflectors and they are considered only because it costs a lot of money to buy a short arc light and a quality factory made reflector.
We need a reflector light combination that is cheap and effective. The light has to come to a point because then it can be collimated into a parallel beam in the range of 2 mm diameter. Several posts ago I mentioned a type of reflector called an orthogonal parabolic refllector which is supposed to give a razor sharp point from a long light source. This reflector is not a parabolic reflector. It is actually an elliptical reflector in that the point is at focus position number 2 but thats what it is called. I will look into it and see if it is useful for a laser projector.
Greetings
This section is a leadin to reflectors. Taking a step by step approach could be like so.
Could use one powerful light and divide in into red green and blue
Could use three smaller light sources and extract the red green and blue. One colour from each light source.
That would mean three reflectors but probably a lot cheaper than a dichroic prism colour splitter.
Could start off without colour splitting and use white light to have a black and white picture.
I would not like to use much more than a 500 watt lamp otherwise its going to increase the electricity account too much. One 500 watt or three 125-150 watt lamps.
Amount of light you get for electricity used.
Information courtesy of Fender4 LCD projector thread page 123.
Low pressure sodium...............200 lumens per watt
High pressure sodium..............130
Metal halide..........................115
Large flourescent....................95
Mercury vapour..................... 56
High brightness LED.................35
Halogen................................22
Household light bulb................16
This shows some light bulbs give far more light per watt than others. An ordinary household tungsten filament lamp gives 16 lumens per watt of electricity. So a 100 watt household bulb would give 1600 lumens. A metal halide on the other hand gives 115 lumens per watt so a 100 watt MH would give 11500 lumens.
Metal halide lamps were developed for LCD projection and would be a good choice but for testing I will be using a 500 watt Halogen lamp because they are only $6 each. The reason is Metal Halides or any arc lamps do not like being turned on and off quickly. They need a period of time 15-30 minutes to cool down before being switched on again. Quick restarting shortens their life. A Halogen lamp is not so critical re turning on and off quickly and being inexpensive it does not matter so much so are more suitable for a test setup.
I have done some initial testing and will report on that soon but there is another important matter to consider.
How do you modulate light.
Modulation of the light beam whether it be a high power laser beam or a high power non laser beam is necessary to see a picture. Modulation frequencies for video are up to 5 mhz thats 5 million times per second. You can't just turn the light on and off. You can't put a mechanical shutter in the light path. Who knows a suitable way to modulate a light beam for video. Anyone.
Ideas welcome.
Possibilities include
Jeffry cell as used in Scophony Tv
Kerr cell
Pockels cell
Faraday rotation
LCD shutter
Acousto-optic
Modulation has to be thought about otherwise with a lot of effort we could get a beam of light and be unable to use it for projection.
This section is a leadin to reflectors. Taking a step by step approach could be like so.
Could use one powerful light and divide in into red green and blue
Could use three smaller light sources and extract the red green and blue. One colour from each light source.
That would mean three reflectors but probably a lot cheaper than a dichroic prism colour splitter.
Could start off without colour splitting and use white light to have a black and white picture.
I would not like to use much more than a 500 watt lamp otherwise its going to increase the electricity account too much. One 500 watt or three 125-150 watt lamps.
Amount of light you get for electricity used.
Information courtesy of Fender4 LCD projector thread page 123.
Low pressure sodium...............200 lumens per watt
High pressure sodium..............130
Metal halide..........................115
Large flourescent....................95
Mercury vapour..................... 56
High brightness LED.................35
Halogen................................22
Household light bulb................16
This shows some light bulbs give far more light per watt than others. An ordinary household tungsten filament lamp gives 16 lumens per watt of electricity. So a 100 watt household bulb would give 1600 lumens. A metal halide on the other hand gives 115 lumens per watt so a 100 watt MH would give 11500 lumens.
Metal halide lamps were developed for LCD projection and would be a good choice but for testing I will be using a 500 watt Halogen lamp because they are only $6 each. The reason is Metal Halides or any arc lamps do not like being turned on and off quickly. They need a period of time 15-30 minutes to cool down before being switched on again. Quick restarting shortens their life. A Halogen lamp is not so critical re turning on and off quickly and being inexpensive it does not matter so much so are more suitable for a test setup.
I have done some initial testing and will report on that soon but there is another important matter to consider.
How do you modulate light.
Modulation of the light beam whether it be a high power laser beam or a high power non laser beam is necessary to see a picture. Modulation frequencies for video are up to 5 mhz thats 5 million times per second. You can't just turn the light on and off. You can't put a mechanical shutter in the light path. Who knows a suitable way to modulate a light beam for video. Anyone.
Ideas welcome.
Possibilities include
Jeffry cell as used in Scophony Tv
Kerr cell
Pockels cell
Faraday rotation
LCD shutter
Acousto-optic
Modulation has to be thought about otherwise with a lot of effort we could get a beam of light and be unable to use it for projection.
Big Bucks are the key
Wow, it's going to cost so much to get this thing going!
I remember browsing through General Scanning's pamphlet's in '89 and they said they had a resonant scanner that was in the works for tv... Never saw anymore from them after the blip about that. Wonder how much they spent trying?! Maybe, 100k or 200k or maybe 1 Mega dollars...he-he
It's true though...just cost a lot of money. And, white light laser (or any laser type combination's with the necessary Wattage), whew, expensive too!
But, imagine the crispness of the picture when you see it!...Someday! Crispity!, Crunchity!
Are ya'll, "LAB" guys from Bell, Litton, Dow-Corning or sometin'?
DIY??? I gotta see this!! We're not Rockefeller's or Gates'.
Just curious...I feel a flame coming. I got my Super-DIY, asbestos pants on though! Only cost $6.99, there's this paint at Kmart that...
Wow, it's going to cost so much to get this thing going!
I remember browsing through General Scanning's pamphlet's in '89 and they said they had a resonant scanner that was in the works for tv... Never saw anymore from them after the blip about that. Wonder how much they spent trying?! Maybe, 100k or 200k or maybe 1 Mega dollars...he-he
It's true though...just cost a lot of money. And, white light laser (or any laser type combination's with the necessary Wattage), whew, expensive too!
But, imagine the crispness of the picture when you see it!...Someday! Crispity!, Crunchity!
Are ya'll, "LAB" guys from Bell, Litton, Dow-Corning or sometin'?
DIY??? I gotta see this!! We're not Rockefeller's or Gates'.
Just curious...I feel a flame coming. I got my Super-DIY, asbestos pants on though! Only cost $6.99, there's this paint at Kmart that...
Big Bucks are the key
Are ya'll, "LAB" guys from Bell, Litton, Dow-Corning or sometin'?
DIY??? I gotta see this!! We're not Rockefeller's or Gates'.
Just curious...I feel a flame coming. I got my Super-DIY, asbestos pants on though! Only cost $6.99, there's this paint at Kmart that...
Sushimasterx,
Thanks for comments. Its encouraging to know that someone reads this stuff.
No I'm not from Bell or any big company or any company at all. Just an ordinary DIY guy working from home in a little far off country called New Zealand, population 3.5 million. We regularly beat the rest of the world at rugby. Hold the 7's rugby world cup. Lord Rutherford first to split the atom was a NZ'r. Sir Edmond Hillary was first to climb Mount Everest. We took the yachting Americas cup from the USA. IBM get a lot of special manufacturing done in New Zealand. Possibly the greatest middle distance runner of all time Sir Peter Snell now working in USA is a New Zealander. Thats just a little about the greatest little country in the world.
What this thread is about is trying to make a "laser" projector on a shoestring. There are only three difficult aspects
Get a beam......................can be done
Modulate a beam.............in progress
Scan a beam...................done
Its not impossible. Just difficult.
Getting back to modulating the beam anyone come up with an easy DIY solution.
For those thinking about how to do this I will quickly run over some of the avaliable options. Bear in mind we need three modulators. One each for red, green and blue so cost is a definite factor.
Electro-optic Put voltage either side of a crystal and it changes its refractive index. Expensive
Acousto-optic Couple high frequency into an optically active material and it gives a means to change beam direction or modulate a beam. Moderately expensive, small beam angle, wavelength dependant.
Digital mirrors. Flick back and forth very quickly. Need to convert analogue information to digital. Not suitable for DIY manufacture because of very small size. Never seen one for sale.
LCD shutter. These you can buy. They are similar to a regular small lcd screen. They need polarised light. They are not cheap. Going that way would do the job but unless you pay big dollars you can only get slow shutters at anything like affordable price.
Kerr cell. One of the original light beam modulators. Very small. Very fast. Need high voltage to operate. Not linear voltage/modulation curve. Optic fluid is nitrobensene, one of the most toxic materials on the planet to humans. Can be done with other optically active liquids such as kerosene.
Pockels cell. Crystal that changes refraction index with applied voltage. Costly.
Jeffree cell. Older type, similar to Acousto-optic operation.
Pcaom. Polychromatic acousto-optic modulator. Nearly an ideal modulator device. Takes in white light, gives out up to 8 separate different coloured modulated beams at a small angle to each other. Mostly used with lasers in light shows. Uses linearly polarised source. High contrast. This device would be 100 percent ok if you could put in white light and get out a single in line coloured beam according to the video picture colour content but it does not quite do that. Modulation speed goes to 100-500k per second, not quite there for true video use. Prices start at $1000 US for 4 channel <5 watt input. You could still use this device by combining the required modulated output beams in fibre optic. Keep an eye on these. If they come down into the $200 range it's definitely a possibility.
Then there is a whole range of specialised light beam modulators mostly in the laboratory special range with prices to match.
We still a long way off a cheap DIY light beam modulator but there is a possibility. What if we had a 2mm collimated beam. Place a small mirror in the beam. A few feet away (for optical leverage) have an obstruction. If the mirror stays put, the beam just clears the obstruction. Full light. Move the mirror ever so slightly so now the beam hits the obstruction and no light passes. No light. By small movement of the mirror you could modulate the light beam 100 percent. Not perfect but it's a start. What could move the mirror at speeds up to five million times per second.
The key points are not much movement but very high speed.
Possibly a piezo-electric element. They can move that fast but can they move the distance required for obstruction modulation. Perhaps we don't even need a mirror. Just move a very light weight obstruction into the beam path.
Are ya'll, "LAB" guys from Bell, Litton, Dow-Corning or sometin'?
DIY??? I gotta see this!! We're not Rockefeller's or Gates'.
Just curious...I feel a flame coming. I got my Super-DIY, asbestos pants on though! Only cost $6.99, there's this paint at Kmart that...
Sushimasterx,
Thanks for comments. Its encouraging to know that someone reads this stuff.
No I'm not from Bell or any big company or any company at all. Just an ordinary DIY guy working from home in a little far off country called New Zealand, population 3.5 million. We regularly beat the rest of the world at rugby. Hold the 7's rugby world cup. Lord Rutherford first to split the atom was a NZ'r. Sir Edmond Hillary was first to climb Mount Everest. We took the yachting Americas cup from the USA. IBM get a lot of special manufacturing done in New Zealand. Possibly the greatest middle distance runner of all time Sir Peter Snell now working in USA is a New Zealander. Thats just a little about the greatest little country in the world.
What this thread is about is trying to make a "laser" projector on a shoestring. There are only three difficult aspects
Get a beam......................can be done
Modulate a beam.............in progress
Scan a beam...................done
Its not impossible. Just difficult.
Getting back to modulating the beam anyone come up with an easy DIY solution.
For those thinking about how to do this I will quickly run over some of the avaliable options. Bear in mind we need three modulators. One each for red, green and blue so cost is a definite factor.
Electro-optic Put voltage either side of a crystal and it changes its refractive index. Expensive
Acousto-optic Couple high frequency into an optically active material and it gives a means to change beam direction or modulate a beam. Moderately expensive, small beam angle, wavelength dependant.
Digital mirrors. Flick back and forth very quickly. Need to convert analogue information to digital. Not suitable for DIY manufacture because of very small size. Never seen one for sale.
LCD shutter. These you can buy. They are similar to a regular small lcd screen. They need polarised light. They are not cheap. Going that way would do the job but unless you pay big dollars you can only get slow shutters at anything like affordable price.
Kerr cell. One of the original light beam modulators. Very small. Very fast. Need high voltage to operate. Not linear voltage/modulation curve. Optic fluid is nitrobensene, one of the most toxic materials on the planet to humans. Can be done with other optically active liquids such as kerosene.
Pockels cell. Crystal that changes refraction index with applied voltage. Costly.
Jeffree cell. Older type, similar to Acousto-optic operation.
Pcaom. Polychromatic acousto-optic modulator. Nearly an ideal modulator device. Takes in white light, gives out up to 8 separate different coloured modulated beams at a small angle to each other. Mostly used with lasers in light shows. Uses linearly polarised source. High contrast. This device would be 100 percent ok if you could put in white light and get out a single in line coloured beam according to the video picture colour content but it does not quite do that. Modulation speed goes to 100-500k per second, not quite there for true video use. Prices start at $1000 US for 4 channel <5 watt input. You could still use this device by combining the required modulated output beams in fibre optic. Keep an eye on these. If they come down into the $200 range it's definitely a possibility.
Then there is a whole range of specialised light beam modulators mostly in the laboratory special range with prices to match.
We still a long way off a cheap DIY light beam modulator but there is a possibility. What if we had a 2mm collimated beam. Place a small mirror in the beam. A few feet away (for optical leverage) have an obstruction. If the mirror stays put, the beam just clears the obstruction. Full light. Move the mirror ever so slightly so now the beam hits the obstruction and no light passes. No light. By small movement of the mirror you could modulate the light beam 100 percent. Not perfect but it's a start. What could move the mirror at speeds up to five million times per second.
The key points are not much movement but very high speed.
Possibly a piezo-electric element. They can move that fast but can they move the distance required for obstruction modulation. Perhaps we don't even need a mirror. Just move a very light weight obstruction into the beam path.
Never give up! Never surrender!
NZ, hope someday to see. Looks like a great place to breath. Are you near any of the places shot in the Rings movie?
I'll have to sit down with a coffee cup and read (and understand) the entire thread.
For starters, the Blue laser DVD recorders are coming out. Their diodes will probably be down in price relatively soon, as DVD recorder production goes up. Then we should see them available relatively cheap, ~2-300$US. Not, sure if the necessary wattages will be available. Maybe soon a white laser diode also.
To my question. Do you think it's possible to utilize these wavelength's from the commonly available diodes to make a correctly colored picture? Or, would true "RGB", wavelength-specific lasers still need to be purchased?
NZ, hope someday to see. Looks like a great place to breath. Are you near any of the places shot in the Rings movie?
I'll have to sit down with a coffee cup and read (and understand) the entire thread.
For starters, the Blue laser DVD recorders are coming out. Their diodes will probably be down in price relatively soon, as DVD recorder production goes up. Then we should see them available relatively cheap, ~2-300$US. Not, sure if the necessary wattages will be available. Maybe soon a white laser diode also.
To my question. Do you think it's possible to utilize these wavelength's from the commonly available diodes to make a correctly colored picture? Or, would true "RGB", wavelength-specific lasers still need to be purchased?
Sushimasterx
I'm not sure what laser wavelenghts are available because for me lasers are too expensive and use too much electricity for the present.
The Schneider laser Tv system now cancelled used
628nm 532nm 446nm
Ordinary diode lasers will have a hard time providing enough light. You need something like 500mw - 2 watts optical power which is quite a lot. Depends on the inner processing used and how efficient that is. Most of the higher priced true laser projectors for venues or for hire use polygon scanning. I have several prices here for polygons of good quality and high speed starting at US $2500.
Message for Fiat1, Mountain_NZ and Piguy.
You were interested in a small mirror for scanning. I found something you might like. Have a look at US patent 5802195. This describes a high displacement piezo type loudspeaker which operates up to 15625hz so could have enough movement and speed to run a scanning mirror. I sent you e-mails as well.
I'm not sure what laser wavelenghts are available because for me lasers are too expensive and use too much electricity for the present.
The Schneider laser Tv system now cancelled used
628nm 532nm 446nm
Ordinary diode lasers will have a hard time providing enough light. You need something like 500mw - 2 watts optical power which is quite a lot. Depends on the inner processing used and how efficient that is. Most of the higher priced true laser projectors for venues or for hire use polygon scanning. I have several prices here for polygons of good quality and high speed starting at US $2500.
Message for Fiat1, Mountain_NZ and Piguy.
You were interested in a small mirror for scanning. I found something you might like. Have a look at US patent 5802195. This describes a high displacement piezo type loudspeaker which operates up to 15625hz so could have enough movement and speed to run a scanning mirror. I sent you e-mails as well.
Hi remp (and all others)!
I must first say that you are amazing! I have been thinking about the scan problem for a long time but it just seemed undoable. The Mihaly-Traub scanner principle is really neat!
As you say, lasers are way too expensive for DIY-ers today. Hopefully this is about to change, though. I think the way to go is DPSS lasers (Diode Pumped Solid State Lasers). These work by having arrays of infrared laser diodes (880 nm I think) "pump" light into a laser crystal (Nd:YAG is a common type). From the laser crystal you get a very good laser beam, much better beam quality than from a laser diode - like a gas laser.
The beam emanating from a YAG crystal is at 1064 nm. This needs to be doubled using a non-linear crystal (KTP for example) and this produces a very nice 532 nm green. It's also possible to use other crystals to get blue and visible red beams.
These lasers come (today) in powers of up to several watts, require very little cooling and very little power (I have seen a 3 watt green DPSS laser running from a standard 240 VAC and cooled by a normal 8 cm computer type fan - it was *beautiful*, and extremely bright, I can tell you!). These lasers cannot be modulated by simply turning them on and off.
It is possible to hobby-build these lasers, at least up to maybe 100 mW, but the parts are expensive themselves, especially for blue and red. Also there's the question of dangerously high levels of invisible infrared radiation.
About laser power: if you want a nice picture in a dark room you can do with just a few hundred mW per square meter (1 sq meter = ~57" in 4:3 format). Use a projection screen -- these have much higher reflection than an ordinary wall. (But if you want good blacks you should use many watts of laser power and project on black satin
)
About modulation: this is a problem (as you have already noticed)... For full PAL resolution (720x576) you need a modulator capable of 11.25 MHz (720x625x25). AOMs is an option as you have already mentioned. EOMs would be ideal, since their contrast ratio can be as high as 1000:1. Homebuilt EOMs need not be more expensive than AOMs, but they require high voltage for operation, and a good knowledge of HVDC electronics. Other than this (not very small detail) they should not be very hard to build.
I will follow your progress on this with lots of interest!
About color temperature: this is complicated and I'm just starting to learn, but I will do my best to learn by explaining. If I'm wrong about anything, please correct me! Most of this is derived from the Poynton Color FAQ (www.inforamp.net/~poynton).
Natural daylight (in northern Europe) has a spectral energy distribution that closely match black-body radiation at 6500 K. This is also called a D65 illuminant. This is a good "standard white".
Computer color screens usually have a higher color temperature, 9300 K (more blue). This is because the blue phosphors are more efficient than the red and green ones, so this is a compromise to get more light but at a less accurate color reproduction.
To understand the rest you first need an understanding of the CIE chromaticity diagram (attached below) and CIE XYZ "tristimulus values" (see the Color FAQ):
The 6500 K white point has CIE chromaticity coordinates (x, y) = (0.3127, 0.3290).
There has been an international agreement of what primaries to use for HDTV. These also closely match the primaries used in ordinary TVs and computer screens. The CIE xy coordinates of these primaries are R = (0.640, 0.330); G = (0.300, 0.600); B = (0.150, 0.060).
These primaries cannot be readily converted into pure laser wavelengths since the phosphors used in TV screens have a much broader spectrum than a laser, but approximately they are (R, G, B) = (607 nm, 557 nm, 465 nm).
If instead lasers are used with (R, G, B) = (635 nm, 532 nm, 473 nm), the corresponding CIE chromaticity coordinates are R = (0.714, 0.286), G = (0.170, 0.797); B = (0.116, 0.074). This gives a better color gamut (more possible colors) except for the deep blue end which is a little bit worse.
Now, how do we calculate the balance between the primaries needed to get D65 white? This is my guess, feel free to correct me if I've made a mistake, and please tell me if I'm doing it right also:
From the Color FAQ: "the color produced by any additive mixture of three primary spectra can be predicted by adding the corresponding fractions of the XYZ components of the primaries". Here we know the resulting color (D65 white) but we do not know the fractions of our primaries to get it. So, we look up the XYZ values (or convert the xy coordinates above to XYZ) of our primaries and the D65 point. We put this into an equation system and after some Gauss-Jordan elimination we get intensity of red = 1.60, intensity of green = 1.00, intensity of blue = 1.27.
I've got no idea if this is really correct but it does make sense: the human eye are most sensitive to green, and we have chosen a blue that is quite bright and therefore should be quite visible.
Well, hope this makes at least a little sense...
// BitNick
I must first say that you are amazing! I have been thinking about the scan problem for a long time but it just seemed undoable. The Mihaly-Traub scanner principle is really neat!
As you say, lasers are way too expensive for DIY-ers today. Hopefully this is about to change, though. I think the way to go is DPSS lasers (Diode Pumped Solid State Lasers). These work by having arrays of infrared laser diodes (880 nm I think) "pump" light into a laser crystal (Nd:YAG is a common type). From the laser crystal you get a very good laser beam, much better beam quality than from a laser diode - like a gas laser.
The beam emanating from a YAG crystal is at 1064 nm. This needs to be doubled using a non-linear crystal (KTP for example) and this produces a very nice 532 nm green. It's also possible to use other crystals to get blue and visible red beams.
These lasers come (today) in powers of up to several watts, require very little cooling and very little power (I have seen a 3 watt green DPSS laser running from a standard 240 VAC and cooled by a normal 8 cm computer type fan - it was *beautiful*, and extremely bright, I can tell you!). These lasers cannot be modulated by simply turning them on and off.
It is possible to hobby-build these lasers, at least up to maybe 100 mW, but the parts are expensive themselves, especially for blue and red. Also there's the question of dangerously high levels of invisible infrared radiation.
About laser power: if you want a nice picture in a dark room you can do with just a few hundred mW per square meter (1 sq meter = ~57" in 4:3 format). Use a projection screen -- these have much higher reflection than an ordinary wall. (But if you want good blacks you should use many watts of laser power and project on black satin
)About modulation: this is a problem (as you have already noticed)... For full PAL resolution (720x576) you need a modulator capable of 11.25 MHz (720x625x25). AOMs is an option as you have already mentioned. EOMs would be ideal, since their contrast ratio can be as high as 1000:1. Homebuilt EOMs need not be more expensive than AOMs, but they require high voltage for operation, and a good knowledge of HVDC electronics. Other than this (not very small detail) they should not be very hard to build.
I will follow your progress on this with lots of interest!
About color temperature: this is complicated and I'm just starting to learn, but I will do my best to learn by explaining. If I'm wrong about anything, please correct me! Most of this is derived from the Poynton Color FAQ (www.inforamp.net/~poynton).
Natural daylight (in northern Europe) has a spectral energy distribution that closely match black-body radiation at 6500 K. This is also called a D65 illuminant. This is a good "standard white".
Computer color screens usually have a higher color temperature, 9300 K (more blue). This is because the blue phosphors are more efficient than the red and green ones, so this is a compromise to get more light but at a less accurate color reproduction.
To understand the rest you first need an understanding of the CIE chromaticity diagram (attached below) and CIE XYZ "tristimulus values" (see the Color FAQ):
The 6500 K white point has CIE chromaticity coordinates (x, y) = (0.3127, 0.3290).
There has been an international agreement of what primaries to use for HDTV. These also closely match the primaries used in ordinary TVs and computer screens. The CIE xy coordinates of these primaries are R = (0.640, 0.330); G = (0.300, 0.600); B = (0.150, 0.060).
These primaries cannot be readily converted into pure laser wavelengths since the phosphors used in TV screens have a much broader spectrum than a laser, but approximately they are (R, G, B) = (607 nm, 557 nm, 465 nm).
If instead lasers are used with (R, G, B) = (635 nm, 532 nm, 473 nm), the corresponding CIE chromaticity coordinates are R = (0.714, 0.286), G = (0.170, 0.797); B = (0.116, 0.074). This gives a better color gamut (more possible colors) except for the deep blue end which is a little bit worse.
Now, how do we calculate the balance between the primaries needed to get D65 white? This is my guess, feel free to correct me if I've made a mistake, and please tell me if I'm doing it right also:
From the Color FAQ: "the color produced by any additive mixture of three primary spectra can be predicted by adding the corresponding fractions of the XYZ components of the primaries". Here we know the resulting color (D65 white) but we do not know the fractions of our primaries to get it. So, we look up the XYZ values (or convert the xy coordinates above to XYZ) of our primaries and the D65 point. We put this into an equation system and after some Gauss-Jordan elimination we get intensity of red = 1.60, intensity of green = 1.00, intensity of blue = 1.27.
I've got no idea if this is really correct but it does make sense: the human eye are most sensitive to green, and we have chosen a blue that is quite bright and therefore should be quite visible.
Well, hope this makes at least a little sense...
// BitNick
Attachments
Correction
I mentioned I had prices for polygons. That should be "prices from manufacturers" for new polygons. 1 from USA 2 from Japan 1 from Germany.The prices were all over $2500 dollars.
Bitnick,
Many thanks for your information. Any further details of DIY EO modulators would be great.
Checked out the internet looking for light modulators. No cheap simple light modulators anywhere. Plenty of complicated ones, plenty of expensive ones. Plenty of state of the art modulators you need an advanced optics degree just to understand the first sentance but no simple no frills light modulators. Could be because modulating light is not a simple business.
To see the modulator problem in context as part of a DIY projector project even though a small scale investigation it is important to realise that good modulation of a light beam is a fundamental part of the whole thing. There would be no point going to all the trouble of building the scanner part and finding a suitable lighting system without being able to modulate the beam(s) with video information. The light beams are not flimsy little things they would be pretty powerful beams of light red green and blue and each beam has to be modulated at high speed. You see the results of modulation as pictures on the screen but behind that has to be some concrete means of modulating each of the light beams whether they be derived from a metal halide light or are three laser beams they still need modulated as the video information requires. This complicated modulation of the beams still has to be done in a way that is suitable for DIY people to duplicate.
Thats why I thought about using a movable lightweight obstruction in the light beam to act as a kind of modulator. Like a very fast shutter. Its a type of modulator that is easy to understand and could be easy to construct. I know it is not a good way to modulate. Normally you would have a light beam and modulate it so the whole beam reduces and increases in strenght according to the video information. The obstruction method does not do that. It simply stops part of the full strenght beam proceeding any further. Its all I have at the moment. It is possible the resultant obstructed beam could be homogenised into a correctly modulated beam.
Needs a very fast piezo-electric type material to move the obstruction and also needs high voltage to operate. The high operating voltage is inconvenient but not a serious problem. The real problem is speed of operation and amount of movement. High speed is usually associated with small movement. Piezo type materials can move at the speed required for a light obstructor but the movement is at most a tenth of a millimeter. That amount of movement would not obscure a 2 mm light beam but several of them might. Say four units forming an iris. There is also the method of optical leverage. If you reflect a light beam from a mirror, and move the mirror a small amount two feet away the light beam will move a lot. You could take this to extreme and measure the beam movement ten feet away. It will be a lot more. That means the mirror only has to move a tenth as far as without optical leverage so it could be possible to use a piezo device even with its small movement. Piezo elements can be stacked to give twice the movement. It is common practice to stack piezo elements say 5 or 10 elements but they can be expensive so that has to be considered. There are new types of piezo elements coming on the market with more movement. These could be useful.
Apart from that, still searching for modulator.
I mentioned I had prices for polygons. That should be "prices from manufacturers" for new polygons. 1 from USA 2 from Japan 1 from Germany.The prices were all over $2500 dollars.
Bitnick,
Many thanks for your information. Any further details of DIY EO modulators would be great.
Checked out the internet looking for light modulators. No cheap simple light modulators anywhere. Plenty of complicated ones, plenty of expensive ones. Plenty of state of the art modulators you need an advanced optics degree just to understand the first sentance but no simple no frills light modulators. Could be because modulating light is not a simple business.
To see the modulator problem in context as part of a DIY projector project even though a small scale investigation it is important to realise that good modulation of a light beam is a fundamental part of the whole thing. There would be no point going to all the trouble of building the scanner part and finding a suitable lighting system without being able to modulate the beam(s) with video information. The light beams are not flimsy little things they would be pretty powerful beams of light red green and blue and each beam has to be modulated at high speed. You see the results of modulation as pictures on the screen but behind that has to be some concrete means of modulating each of the light beams whether they be derived from a metal halide light or are three laser beams they still need modulated as the video information requires. This complicated modulation of the beams still has to be done in a way that is suitable for DIY people to duplicate.
Thats why I thought about using a movable lightweight obstruction in the light beam to act as a kind of modulator. Like a very fast shutter. Its a type of modulator that is easy to understand and could be easy to construct. I know it is not a good way to modulate. Normally you would have a light beam and modulate it so the whole beam reduces and increases in strenght according to the video information. The obstruction method does not do that. It simply stops part of the full strenght beam proceeding any further. Its all I have at the moment. It is possible the resultant obstructed beam could be homogenised into a correctly modulated beam.
Needs a very fast piezo-electric type material to move the obstruction and also needs high voltage to operate. The high operating voltage is inconvenient but not a serious problem. The real problem is speed of operation and amount of movement. High speed is usually associated with small movement. Piezo type materials can move at the speed required for a light obstructor but the movement is at most a tenth of a millimeter. That amount of movement would not obscure a 2 mm light beam but several of them might. Say four units forming an iris. There is also the method of optical leverage. If you reflect a light beam from a mirror, and move the mirror a small amount two feet away the light beam will move a lot. You could take this to extreme and measure the beam movement ten feet away. It will be a lot more. That means the mirror only has to move a tenth as far as without optical leverage so it could be possible to use a piezo device even with its small movement. Piezo elements can be stacked to give twice the movement. It is common practice to stack piezo elements say 5 or 10 elements but they can be expensive so that has to be considered. There are new types of piezo elements coming on the market with more movement. These could be useful.
Apart from that, still searching for modulator.
EOMs - how they work
Ok, here's some general info on EOMs (I'm not an expert but I have seen them in operation and during construction)...
EOMs work by "twisting" the polarization of light. An EOM setup would consist of
1) a polarizer (if your light source isn't polarized from the beginning, like most Gas and DPSS lasers)
2) the EOM crystal
3) an "analyzer" -- this can be either another polarizer or (for high power applications) a crystal that splits the beam by polarization -- one useful beam and one "waste" beam. The waste beam can be pointed to a black aluminium block or something similar that can take high amounts of power/heat.
When the light passes through the EOM crystal, its polarization is rotated (actually, this is due to phase shifts that is caused by birefringence in the crystal -- don't ask me about it because I don't really know what causes birefringence or how it really works).
Applying an electric field over the crystal changes the amount of phase shift, and therefore the amount of light blocked by the analyzer.
You could build an EOM by taking a fitting crystal (KDP?) cut in an appropriate way. It should be as high and wide as your beam diameter, and as long as possible. The thinner the crystal is the higher the electrical field per applied voltage -- this means lower voltage is needed. Therefore don't use a crystal higher than the beam diameter. Also, the crystal is not uniform so it is important to have the axles of the crystal right.
Glue one of the long sides (the correct one!) into place on a piece of copper (using conductive glue) -- the piece of copper will be your ground/earth and heat sink.
"Paint" the opposite (now upper) side of the crystal with more conductive glue, and connect it to your HVDC source. Place the laser so that it shines into one of the ends of the crystal and place the analyzer on the opposite side. Control the HVDC source with a video signal. Well, that's it!
Of course there will be a lot of problems -- how to change the voltage over the crystal (maybe 150V p-p) fast enough (12 MHz) is only one of them. Thermal stability is another.
I think if someone thinks themselves able to deal with the HVDC modulation, then go for it!
Also take a look at http://cord.org/cm/leot/course04_mod07/mod04_07.htm
// BitNick
Ok, here's some general info on EOMs (I'm not an expert but I have seen them in operation and during construction)...
EOMs work by "twisting" the polarization of light. An EOM setup would consist of
1) a polarizer (if your light source isn't polarized from the beginning, like most Gas and DPSS lasers)
2) the EOM crystal
3) an "analyzer" -- this can be either another polarizer or (for high power applications) a crystal that splits the beam by polarization -- one useful beam and one "waste" beam. The waste beam can be pointed to a black aluminium block or something similar that can take high amounts of power/heat.
When the light passes through the EOM crystal, its polarization is rotated (actually, this is due to phase shifts that is caused by birefringence in the crystal -- don't ask me about it because I don't really know what causes birefringence or how it really works).
Applying an electric field over the crystal changes the amount of phase shift, and therefore the amount of light blocked by the analyzer.
You could build an EOM by taking a fitting crystal (KDP?) cut in an appropriate way. It should be as high and wide as your beam diameter, and as long as possible. The thinner the crystal is the higher the electrical field per applied voltage -- this means lower voltage is needed. Therefore don't use a crystal higher than the beam diameter. Also, the crystal is not uniform so it is important to have the axles of the crystal right.
Glue one of the long sides (the correct one!) into place on a piece of copper (using conductive glue) -- the piece of copper will be your ground/earth and heat sink.
"Paint" the opposite (now upper) side of the crystal with more conductive glue, and connect it to your HVDC source. Place the laser so that it shines into one of the ends of the crystal and place the analyzer on the opposite side. Control the HVDC source with a video signal. Well, that's it!
Of course there will be a lot of problems -- how to change the voltage over the crystal (maybe 150V p-p) fast enough (12 MHz) is only one of them. Thermal stability is another.
I think if someone thinks themselves able to deal with the HVDC modulation, then go for it!
Also take a look at http://cord.org/cm/leot/course04_mod07/mod04_07.htm
// BitNick
BitNick,
Thanks for the info. Sounds like the hardest job would be to locate a ready cut crystal. I might try the local University see if they can help or failing that someone in the gemstone business.
The other parts you mention would be readily avaliable and handling the high voltage is not a serious problem.
Thanks for the info. Sounds like the hardest job would be to locate a ready cut crystal. I might try the local University see if they can help or failing that someone in the gemstone business.
The other parts you mention would be readily avaliable and handling the high voltage is not a serious problem.
Hey everyone,
Sorry I haven't posted in a while. I did some research into CRT projectors, and found that some very nice HDTV grade projectors can be had for sometimes less than $1000. So I sort of lost interest in building a projector. Anyways, I decided to come by and see if there have been any developments. I was just thinking about the possibility of creating a single scan line display and then scanning that to produce the full display. It would reduce the required operating frequency of the mirror by roughly an order of 3. I guess the hard part would be everything else: creating the electronics necessary to drive the display one scan line at a time, actually creating the display (led array?) and focusing the light from the display to a coherent beam. Kinda crazy, I know. I was just thinking that if there's absolutely no way to get a fast enough mirror, maybe we should think about ways to get around that? Oh well, just a thought.
Sorry I haven't posted in a while. I did some research into CRT projectors, and found that some very nice HDTV grade projectors can be had for sometimes less than $1000. So I sort of lost interest in building a projector. Anyways, I decided to come by and see if there have been any developments. I was just thinking about the possibility of creating a single scan line display and then scanning that to produce the full display. It would reduce the required operating frequency of the mirror by roughly an order of 3. I guess the hard part would be everything else: creating the electronics necessary to drive the display one scan line at a time, actually creating the display (led array?) and focusing the light from the display to a coherent beam. Kinda crazy, I know. I was just thinking that if there's absolutely no way to get a fast enough mirror, maybe we should think about ways to get around that? Oh well, just a thought.
Greetings
Hi Piguy. Thanks for info. An HDTV projector for less than $1000. Second hand ??.
Creating one line of video would solve the scan problem because you would only need to scan a horizontal line down the screen. The scan down would be a piece of cake to do. Creating one line I presume you mean a Horizontal raster line of video has been tried before. You can easily (=expensively) get one complete video line to register in a crystal with the correct drive then display that whole line with a very high power fast pulsed light source. If you use a pulsed laser at the power required it would be far too dangerous to have front project has to be rear projection and even then have to go to extraordinary trouble to make sure no high level light pulses come through the rear projection screen. There have been attempts using a whole lot of light beams extracted from a powerful light source but the one problem you keep running into is if you have say 600 light beams to make up a complete horizontal line, you also need 600 modulators and 600 modulator control circuits. There are people working on the method you say. For example Silicon Light I believe is the name of one company. Dawoo Hitachi Matsushita and many others with a variety of all at once methods.
It is very difficult as you say to make a mirror scan correctly at TV speed and other methods of H scanning are impractical for DIY or expensive like very expensive. Polygons can do it, Acousto-optic deflectors can do it, Electro-optic can do it. Several other techniques can also be used but when you look right into it they are expensive or have some really serious problem as far as a DIY person is concerned. Light shows are using modern equipment which is coming close to TV raster scanning but check the prices of their equipment.
If somebody seriously wanted to build a laser projector with good specs you can. White light lasers are avaliable off the shelf. Polygon high speed scanners are avaliable off the shelf. Modulators likewise. For a small setup suitable for home use you would be looking at $15,000 - $20,000. Who would spend that sort of money when you can buy a very high spec LCD projector for half or a quarter that price. Price is the determining factor that is why you do not see home laser projectors for sale.
But I am not put off by that. Sooner or later I will have a cheap usable laser projector. May not be for a while but the technical challenge is just too good to pass up.
There has been a large upheavel in the large screen projection industry which traditionaly has been dominated by LCD and DLD and that is the appearance from the laboratories of a new projector technology using a large screen covered in I understand ORGANIC Led material. These are like having a screen with a whole lot of led's fitted and where the picture should be bright red the red led lights up. They say these can be printed or silkscreened and you dont need any form of projector just a screen and control box. They can even be rolled up. Search for OLED. In the shops in a year or two.
Hi Piguy. Thanks for info. An HDTV projector for less than $1000. Second hand ??.
Creating one line of video would solve the scan problem because you would only need to scan a horizontal line down the screen. The scan down would be a piece of cake to do. Creating one line I presume you mean a Horizontal raster line of video has been tried before. You can easily (=expensively) get one complete video line to register in a crystal with the correct drive then display that whole line with a very high power fast pulsed light source. If you use a pulsed laser at the power required it would be far too dangerous to have front project has to be rear projection and even then have to go to extraordinary trouble to make sure no high level light pulses come through the rear projection screen. There have been attempts using a whole lot of light beams extracted from a powerful light source but the one problem you keep running into is if you have say 600 light beams to make up a complete horizontal line, you also need 600 modulators and 600 modulator control circuits. There are people working on the method you say. For example Silicon Light I believe is the name of one company. Dawoo Hitachi Matsushita and many others with a variety of all at once methods.
It is very difficult as you say to make a mirror scan correctly at TV speed and other methods of H scanning are impractical for DIY or expensive like very expensive. Polygons can do it, Acousto-optic deflectors can do it, Electro-optic can do it. Several other techniques can also be used but when you look right into it they are expensive or have some really serious problem as far as a DIY person is concerned. Light shows are using modern equipment which is coming close to TV raster scanning but check the prices of their equipment.
If somebody seriously wanted to build a laser projector with good specs you can. White light lasers are avaliable off the shelf. Polygon high speed scanners are avaliable off the shelf. Modulators likewise. For a small setup suitable for home use you would be looking at $15,000 - $20,000. Who would spend that sort of money when you can buy a very high spec LCD projector for half or a quarter that price. Price is the determining factor that is why you do not see home laser projectors for sale.
But I am not put off by that. Sooner or later I will have a cheap usable laser projector. May not be for a while but the technical challenge is just too good to pass up.
There has been a large upheavel in the large screen projection industry which traditionaly has been dominated by LCD and DLD and that is the appearance from the laboratories of a new projector technology using a large screen covered in I understand ORGANIC Led material. These are like having a screen with a whole lot of led's fitted and where the picture should be bright red the red led lights up. They say these can be printed or silkscreened and you dont need any form of projector just a screen and control box. They can even be rolled up. Search for OLED. In the shops in a year or two.
Richard,
this OLED developement is indeed exiting, there are even existing prototypes, but i think if you want LARGE images it's hard to handle. Look at the limitations of plasma screens.. The size of a modern PJ isn't much more than a radio clock, it can project 600" on a white wall, have an 1800:1 contrast ratio (like the expected 12° mirror HP-projector), has zoom lenses, lightweight...
The only, but main disadvantage is expensive bulb.
I don't know how they handle the power consumption of let's say 2.500.000 OLEDs for XGA res. And if they built it in various sizes, there is an amount of production costs. For now i would not hope for quick products. The same with lasers as far i can see.
BTW, i did it! Bought a 3-panel projector of ebay, 800 ANSI, 300:1 contrast, 1 year WRNTY for 1300 EURO. All i can say, compared to my OHP setup it's another quantum step! Simply GREAT!!
So i hope to see a good final soccer game!
Cheers
xblocker
this OLED developement is indeed exiting, there are even existing prototypes, but i think if you want LARGE images it's hard to handle. Look at the limitations of plasma screens.. The size of a modern PJ isn't much more than a radio clock, it can project 600" on a white wall, have an 1800:1 contrast ratio (like the expected 12° mirror HP-projector), has zoom lenses, lightweight...
The only, but main disadvantage is expensive bulb.
I don't know how they handle the power consumption of let's say 2.500.000 OLEDs for XGA res. And if they built it in various sizes, there is an amount of production costs. For now i would not hope for quick products. The same with lasers as far i can see.
BTW, i did it! Bought a 3-panel projector of ebay, 800 ANSI, 300:1 contrast, 1 year WRNTY for 1300 EURO. All i can say, compared to my OHP setup it's another quantum step! Simply GREAT!!
So i hope to see a good final soccer game!
Cheers
xblocker
Greetings
Hi Xblocker. I agree. Modern small 3 panel projectors certainly are a very useful device easy to carry light weight low power dont even need to carry round a screen just project to a white wall but the display market is so large there is a very big driving force to find and market alternatives to LCD. There are as well long term very difficult problems with LCD particulary the panel production yield and light bulb cost and service life. For the present there is no low cost high output light alternative except for the new contactless 100,000 lumen lamps smaller than a golf ball driven by microwaves which are just becoming avaliable in the $1000-$1500 price range. They may come down in price and compete or be better/cheaper than present bulbs.
Congrats on getting a 3 panel projector. Isn't that world cup soccer fantastic. We have good TV free to air coverage here in New Zealand and I sit glued to my large screen every night. Comes on at 11 each night for couple of hours with live coverage and replays.
Hi Xblocker. I agree. Modern small 3 panel projectors certainly are a very useful device easy to carry light weight low power dont even need to carry round a screen just project to a white wall but the display market is so large there is a very big driving force to find and market alternatives to LCD. There are as well long term very difficult problems with LCD particulary the panel production yield and light bulb cost and service life. For the present there is no low cost high output light alternative except for the new contactless 100,000 lumen lamps smaller than a golf ball driven by microwaves which are just becoming avaliable in the $1000-$1500 price range. They may come down in price and compete or be better/cheaper than present bulbs.
Congrats on getting a 3 panel projector. Isn't that world cup soccer fantastic. We have good TV free to air coverage here in New Zealand and I sit glued to my large screen every night. Comes on at 11 each night for couple of hours with live coverage and replays.
off the beaten path style news!
Today I have heard of the sucessful experimentattion of scientists also the country of New Zealand making first transportation of matter repeatedley! the have sent a laser beam from one place to the others with matter transportation devices!a
are you include this research also?
i can not believe and it is so fascination!
it is a same idea as seen in star trek movies transporter I think!
i see also news for prediction of small particle assembleyr for prediction in coming 5 years!
please request a answer to discuss if free
thank you for time here
AL
Today I have heard of the sucessful experimentattion of scientists also the country of New Zealand making first transportation of matter repeatedley! the have sent a laser beam from one place to the others with matter transportation devices!a
are you include this research also?
i can not believe and it is so fascination!
it is a same idea as seen in star trek movies transporter I think!
i see also news for prediction of small particle assembleyr for prediction in coming 5 years!
please request a answer to discuss if free
thank you for time here
AL
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