Guys,
Here is a picture of a computer optimized wide angle cooke triplet which should work with LCD of 17 inch wide screen format. It has 450 mm FL and 40 degrees total field of vision. I will post design information and the lens can be scaled down for use with 15 inch LCD and lower FL.
Hezz
Here is a picture of a computer optimized wide angle cooke triplet which should work with LCD of 17 inch wide screen format. It has 450 mm FL and 40 degrees total field of vision. I will post design information and the lens can be scaled down for use with 15 inch LCD and lower FL.
Hezz
Attachments
Guys,
Here is a zip file which is a microsoft word document that has the technical drawings and spacing information for this lens design. If anyone out there needs this file in another word processor format just ask and I can probably put it in any major format as long as the wordprocessor can insert EMF (enhanced meta files) format.
Hezz
Here is a zip file which is a microsoft word document that has the technical drawings and spacing information for this lens design. If anyone out there needs this file in another word processor format just ask and I can probably put it in any major format as long as the wordprocessor can insert EMF (enhanced meta files) format.
Hezz
For those interested,
Here is a zip file of a solidworks e-drawing of the lens solid model. With this you can view the lens design in 3D. Here is what you have to do.
1) Go to Solidworks home web page and locate the free e-drawing download.
2) Download solidworks e-drawings onto your computer and install it.
3) Download and unzip the following file.
4) Load it into Solidworks e-drawings and enjoy.
With e-drawing you can manipulate the model in real 3D space but you can not edit it. You can however, mark up notes and questions on the model and perhaps save the screen as a jpeg.
Enjoy.
Hezz
Here is a zip file of a solidworks e-drawing of the lens solid model. With this you can view the lens design in 3D. Here is what you have to do.
1) Go to Solidworks home web page and locate the free e-drawing download.
2) Download solidworks e-drawings onto your computer and install it.
3) Download and unzip the following file.
4) Load it into Solidworks e-drawings and enjoy.
With e-drawing you can manipulate the model in real 3D space but you can not edit it. You can however, mark up notes and questions on the model and perhaps save the screen as a jpeg.
Enjoy.
Hezz
Important information
To anyone who has downloaded the drawing files there is something you need to be aware of. It has to do with the sign conventions for numbers that the optical design software uses.
On the first lens it shows the second surface of the lens as having something like -8xxx.xxx number. Do not construe this to be a negative surface. In fact this is a positive surface but because everything is referenced to the first surface in terms of direction it is a negative number. In other words it is a positive surface but pointing the other direction. That is why it has a negative number. Because the curvature is so small it may appear as a straight or negative surface on a drawing. Hence my need to warn you all.
Hezz
To anyone who has downloaded the drawing files there is something you need to be aware of. It has to do with the sign conventions for numbers that the optical design software uses.
On the first lens it shows the second surface of the lens as having something like -8xxx.xxx number. Do not construe this to be a negative surface. In fact this is a positive surface but because everything is referenced to the first surface in terms of direction it is a negative number. In other words it is a positive surface but pointing the other direction. That is why it has a negative number. Because the curvature is so small it may appear as a straight or negative surface on a drawing. Hence my need to warn you all.
Hezz
... what makes it "High-end"? I thought you were working on a multi lens design.
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www.diybuildergroup.com
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www.diybuildergroup.com
JCB,
What makes it high end is that it is optimized to the point where it can no longer be improved without making the system more complex by adding more elements or by adding aspheric surfaces. This lens if built to spec would outperform any four element system that you could put together without going through the same computer optimization. In years past it took engineers months doing hundreds of calculations to approach a design like this but a computer can do millions of calculations in only a second or two.
We can also do a computer optimization for a four element lens design also. In fact by modifing this design by making the final lens into a cemented doublet we can make a tessar lens with somewhat better performance.
What I am saying is that using trial and error by mixing four lenses together is realistically going to be very difficult because you don't have enough lens values or time to look at every combination. Granted you could build the lens with stock lenses but it would perform lower than an optimized one of simpler design.
So we have the option of building a non optimized lens out of stock components or of starting with an optimized design and perhaps trying to find stock lenses for a couple of the lenses and leave one lens variable open for a custom made lens. Trying to optimize the design that way.
If you have a way to communicate with me your lens configuration I will model it and we will see how good it is. Perhaps it can be optimized with only one custom lens or something.
Hezz
What makes it high end is that it is optimized to the point where it can no longer be improved without making the system more complex by adding more elements or by adding aspheric surfaces. This lens if built to spec would outperform any four element system that you could put together without going through the same computer optimization. In years past it took engineers months doing hundreds of calculations to approach a design like this but a computer can do millions of calculations in only a second or two.
We can also do a computer optimization for a four element lens design also. In fact by modifing this design by making the final lens into a cemented doublet we can make a tessar lens with somewhat better performance.
What I am saying is that using trial and error by mixing four lenses together is realistically going to be very difficult because you don't have enough lens values or time to look at every combination. Granted you could build the lens with stock lenses but it would perform lower than an optimized one of simpler design.
So we have the option of building a non optimized lens out of stock components or of starting with an optimized design and perhaps trying to find stock lenses for a couple of the lenses and leave one lens variable open for a custom made lens. Trying to optimize the design that way.
If you have a way to communicate with me your lens configuration I will model it and we will see how good it is. Perhaps it can be optimized with only one custom lens or something.
Hezz
Perhaps in the future but it would be very expensive to have made. The number of elements jumps up to about 8 -12 lenses and some of them would be hard to make. If I am going to design a zoom lens it is going to be a variable compression anamorphic lens which will work like a zoom lens but only in the vertical or horizontal plane.
Now as to making the lens. At this point you have two choices. One is to take the plans to an optical design firm and have them custom grind the lenses for you. I imagine this would not be cheap. The other is to make the lenses yourself by hand and then have them coated somewhere with the AR coating. I was hoping that someone out there had better access and funds to try to have one made. In the future I may try and redesign the lens for use with plastic lenses that can be hand made more easily but there is no reason that the lenses could not be made by hand. It's just work intensive. I may try and come up with a method that is doable in the future. Stay tuned, who knows what the future will bring.
Hezz
Now as to making the lens. At this point you have two choices. One is to take the plans to an optical design firm and have them custom grind the lenses for you. I imagine this would not be cheap. The other is to make the lenses yourself by hand and then have them coated somewhere with the AR coating. I was hoping that someone out there had better access and funds to try to have one made. In the future I may try and redesign the lens for use with plastic lenses that can be hand made more easily but there is no reason that the lenses could not be made by hand. It's just work intensive. I may try and come up with a method that is doable in the future. Stay tuned, who knows what the future will bring.
Hezz
Hehehehe try years bud but yeah i know what u mean, the age of computers my son has made life a whole lot easier and faster.
Trev
Ive looked into it hezz, $2k for the tooling on each lens for custom lenses, that price quote was from edmunds, and i dont see it much cheaper then that anywhere else.
Trev
Trev,
That price quote doesn't surprise me. I know there are other companies who would do it for less but it still would not be cheap. I think my eventual design goal will be to make this lens into a tessar with some plastic lenses and then make the lenses by hand. The highest precision lenses have historically been made by hand until just in the last five years where advance CNC machines have taken over a lot of the production. However, most of the machines are designed to do smaller lenses of say less than 100 mm.
I will have to study some more on hand griding methods for lenses. Plus I will have to get a few more measuring devices and possibly a small surface plate. I already know how I can make the lenses relatively cheap from acrylic plate but I would need access to a CNC lathe and even though I have the CNC programming knowledge and access to the necessary software the cost of machine time is high.
Hezz
That price quote doesn't surprise me. I know there are other companies who would do it for less but it still would not be cheap. I think my eventual design goal will be to make this lens into a tessar with some plastic lenses and then make the lenses by hand. The highest precision lenses have historically been made by hand until just in the last five years where advance CNC machines have taken over a lot of the production. However, most of the machines are designed to do smaller lenses of say less than 100 mm.
I will have to study some more on hand griding methods for lenses. Plus I will have to get a few more measuring devices and possibly a small surface plate. I already know how I can make the lenses relatively cheap from acrylic plate but I would need access to a CNC lathe and even though I have the CNC programming knowledge and access to the necessary software the cost of machine time is high.
Hezz
Glass 40 degree triplet update
Guys,
for those who are interested I think I have come up with a way to make this lens DIY style for a more reasonable price. It will still not be really cheap but maybe 200 - 300 dollars.
First lets talk about the lens and it's resolution. The way I figure it the average dot size for a high resolution CRT monitor is around .24 mm. This dot consists of three color pixels so lets say that for a lens system to accurately focus on these small objects it must be able to focus each subpixel. So we need a lens that can focus a spot size of .08 mm to be able to accurately focus the image.
Now I don't know exactly how the pixel size arrangement in an LCD corresponds to that of a CRT monitor but since most CRT's are somewhat higher resolution than a LCD I am going to assume that the LCD pixels are just slightly larger. So what this comes down to is that we need a lens system that can accurately focus an image as small as .08 mm or 80 microns.
AS can be seen in this spot diagram for the glass 40 degree triplet it can focus down to about 44 microns of spot size on the paraxial axis. I have compared it to a four element optimized glass tessar lens and the tessar is slightly better giving a 32 micron spot for the paraxial axis. For most application the slight improvement of the tessar over the cooke triplet does not justify the cost and added complexity. For us it shouldn't matter too much as the cooke has twice the on-axis resolution that we need.
Hezz
Guys,
for those who are interested I think I have come up with a way to make this lens DIY style for a more reasonable price. It will still not be really cheap but maybe 200 - 300 dollars.
First lets talk about the lens and it's resolution. The way I figure it the average dot size for a high resolution CRT monitor is around .24 mm. This dot consists of three color pixels so lets say that for a lens system to accurately focus on these small objects it must be able to focus each subpixel. So we need a lens that can focus a spot size of .08 mm to be able to accurately focus the image.
Now I don't know exactly how the pixel size arrangement in an LCD corresponds to that of a CRT monitor but since most CRT's are somewhat higher resolution than a LCD I am going to assume that the LCD pixels are just slightly larger. So what this comes down to is that we need a lens system that can accurately focus an image as small as .08 mm or 80 microns.
AS can be seen in this spot diagram for the glass 40 degree triplet it can focus down to about 44 microns of spot size on the paraxial axis. I have compared it to a four element optimized glass tessar lens and the tessar is slightly better giving a 32 micron spot for the paraxial axis. For most application the slight improvement of the tessar over the cooke triplet does not justify the cost and added complexity. For us it shouldn't matter too much as the cooke has twice the on-axis resolution that we need.
Hezz
Attachments
The home manufacturing method
OK,
now here is the procedure for the home manufacturing of this lens.
First the lenses will be compression molded in a small metal press with machined inserts.
A small home made kiln will be made that can heat small glass blanks up to a moldable temperature. This can be made realatively cheaply.
The exact lens volume will be calculated and core cut blanks of the proper glass type will be ordered. As far as I can tell these are relatively cheap. Maybe 20 - 30 dollars for each lens material.
The metal press will have stainless steel pucks that are interchangable that have the lens curves machined into them. This will be best done by CNC but can be done with a manual lathe by making some kind of curve jig.
The mold pucks will then be hand ground using conventional hand lens grinding techniques to get the mold cavities to a high standard.
Then we put the proper metal pucks into the press and we put the metal press on a small portable hot plate to keep the mold hot and put the precisely sized lens blanks into the little kiln until they are soft enough to mold. Then we put the softened glass blank into the press and compress the mold and wait for it to cool.
When it comes out it should be of very high quality and we finish the process by hand polishing each lens with a pitch lap.
Then we have the lenses coated with AR coating.
There is also the possibility of having the lenses mounted in a water tight lens housing and using index matching liquids between the lenses. Done properly this can work as good or better than AR coatings on the lens.
Hezz
OK,
now here is the procedure for the home manufacturing of this lens.
First the lenses will be compression molded in a small metal press with machined inserts.
A small home made kiln will be made that can heat small glass blanks up to a moldable temperature. This can be made realatively cheaply.
The exact lens volume will be calculated and core cut blanks of the proper glass type will be ordered. As far as I can tell these are relatively cheap. Maybe 20 - 30 dollars for each lens material.
The metal press will have stainless steel pucks that are interchangable that have the lens curves machined into them. This will be best done by CNC but can be done with a manual lathe by making some kind of curve jig.
The mold pucks will then be hand ground using conventional hand lens grinding techniques to get the mold cavities to a high standard.
Then we put the proper metal pucks into the press and we put the metal press on a small portable hot plate to keep the mold hot and put the precisely sized lens blanks into the little kiln until they are soft enough to mold. Then we put the softened glass blank into the press and compress the mold and wait for it to cool.
When it comes out it should be of very high quality and we finish the process by hand polishing each lens with a pitch lap.
Then we have the lenses coated with AR coating.
There is also the possibility of having the lenses mounted in a water tight lens housing and using index matching liquids between the lenses. Done properly this can work as good or better than AR coatings on the lens.
Hezz
Multi lens design
In regards to making a zoom lens design. I am of the opinion that it would be better to have a simple objective of the approximately correct focal length and then build a variable anamorphic lens system which can be easily removed from the projector. Please look at the anamorphic thread to see how some of those lenses were actually made in the past.
It is far easier for most to move the projector a little to get the correct picture size than to make a zoom lens.
Hezz
In regards to making a zoom lens design. I am of the opinion that it would be better to have a simple objective of the approximately correct focal length and then build a variable anamorphic lens system which can be easily removed from the projector. Please look at the anamorphic thread to see how some of those lenses were actually made in the past.
It is far easier for most to move the projector a little to get the correct picture size than to make a zoom lens.
Hezz
I don't know much about lens design or requirements, but when reading this thread one source came to mind for making custom lenses of various strengths cheaply, eyeglasses.
Is it possible to make a design which would use the size and strength of lenses producable by optomatrists? Perhaps the lenses would be too small, have too small a range of focal length, or not be precise enough, but I thought it might be a good idea.
Rather than having custom lenses made you could even use piece together a lens system with used eyeglasses for nothing.
Is it possible to make a design which would use the size and strength of lenses producable by optomatrists? Perhaps the lenses would be too small, have too small a range of focal length, or not be precise enough, but I thought it might be a good idea.
Rather than having custom lenses made you could even use piece together a lens system with used eyeglasses for nothing.
z2895,
The size and focal lengths that we are dealing with with this lens takes it outside of making it with common things like eyeglass blanks or even off the shelf lenses.
Typically off the shelf lenes are only available in sizes up to 80 mm in diameter and that is smaller than the smallest lens in this system. Also, getting the exact prescriptions would not likely be possible with off the shelf lenses.
Also this lens requires certain glass types to work properly and they would not be available in eyeglass lens blanks.
Hezz
The size and focal lengths that we are dealing with with this lens takes it outside of making it with common things like eyeglass blanks or even off the shelf lenses.
Typically off the shelf lenes are only available in sizes up to 80 mm in diameter and that is smaller than the smallest lens in this system. Also, getting the exact prescriptions would not likely be possible with off the shelf lenses.
Also this lens requires certain glass types to work properly and they would not be available in eyeglass lens blanks.
Hezz
Posting something on this thread to get it out of the arcives for a time as someone has found possible builder of the lens.
Hezz
Hezz
CNC lathe
Greetings all.
First off, I am in the process of making my own projector and trying to figure out what projection lens to use has brought me to this thread.
I happen to operate the CNC lathe our company uses and am very interested in the possibility of manufacturing my own lenses. Metals are what we mostly deal in with stainless steel as the most common , although I have done some telfon machining.
I am not an experienced machinist by any means, I just happen to have enough knowledge to allow the company to justified the expense to support our valves and customers. If I try and am successful I would like to send a set to someone experienced here to examine and test them.
Luckily, I am the only one who knows how to operate the lathe and it can go for days without being used. If I dont have the tooling to do this then it wont happen due to the expense.
Let me know what you guys think
Greetings all.
First off, I am in the process of making my own projector and trying to figure out what projection lens to use has brought me to this thread.
I happen to operate the CNC lathe our company uses and am very interested in the possibility of manufacturing my own lenses. Metals are what we mostly deal in with stainless steel as the most common , although I have done some telfon machining.
I am not an experienced machinist by any means, I just happen to have enough knowledge to allow the company to justified the expense to support our valves and customers. If I try and am successful I would like to send a set to someone experienced here to examine and test them.
Luckily, I am the only one who knows how to operate the lathe and it can go for days without being used. If I dont have the tooling to do this then it wont happen due to the expense.
Let me know what you guys think
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