17 inch 16:9 assault on high end project

[Hezz]

Well guys,

I'm back for a while and I hope to eventually finish a projector through to a finished project. For a while I gave up on this DIY projector thing because I could not find a high resolution 16:9 LCD and lens combination that I could be happy with.

Allen over at DIYprojectorcompany and Lumenlabs have now introduced some products that I hope will help me in this persuit.

I have perchaced Allens 135 mm diameter 450 mm FL lens and tested it and it seems to be a better lens that the typical OHP lenses both for brightness and image through size. It also seems to work with a 17 inch LCD and maybe a 19 inch one.

Many will dislike this project because it is large but for me this is easier to work with and impliments all of my ideas that I have pondered over the last couple of years.

Although the pictures do not show it. This is a roll around self standing projector that will be stored in the corner and moved out for viewing. The wheels are missing on the models.

My intension is to use a 17 inch 16:9 aspect ratio LCD so that I can despense with an anamorphic attachment. The projector uses these main ideas.

1) Deep parabolic reflector to capture more total light and collimate the light into a relatively axial orientation.

2) Enclosed and air cooled light bulb housing which has a UV and IR filter and is cooled with a large heat sink.

3) Light recycling polarizing 45 degree angle reflector made of simple and relatively inexpensive parts.

4) Simple light path. One frenel lens collapsoing collimated light into a longer FL light cone prior to the LCD.

5) No fresnel in LCD to objective light path.

Here was the first conceptual design model before I started working on the deep parabolic reflector.

Hezz

[Hezz]

The above picture shows the two peice light engine assembly but consists of a long paramidal light pipe. The next picture shows the upper portion of the deep parabolic light pipe that I will attempt to make out of hand polished aluminum sheet. The large lens is to scale and I have started work on both the lens mounting and focusing mount. I have also build the frame all except for the lower pedestal stand. Real pictures later perhaps.

[Hezz]

The bottom of the two piece light reflector is made out of machine and polished aluminum and has a recess for a piece of IR glass which captures much of the heat from the bulb and transfers it into the heatsink.

[Hezz]

The light recycler reflector relies on simple and relatively easy construction methods. It has a backing of 1 1/2 inch thick MDF to keep the mirror flat. Then mirror reflective mylar film is bonded to the flat surface followed by a 1/4 wave retarding film.

Then square pieces of clear acrylic are bonded in rows with reflective mylar film bonded to all of there sides with the shiny side facing in.

Finally the initial mirror surface is bonded to the acrylic pieces and is a polarizing reflective film that reflects one polarization state at 45 degrees and lest the other pass (from the front). Light of the incorrect polarization state is reflected into the cube and bounces and make two passes through the 1/4 wave retarding film.

The success of this recycling reflector depends on being able to find and inexpensive polarizing reflector that has the correct behavior. I have seen illustrations on some web sites that show this principle.

Any help with sources for the right films would be appreciated.

Hezz

[Honukele]

Hezz - Your ideas are brilliant and inspiring.

I have simpler ambitions. Would you mind giving me your opinion on my simple design for a light recycler? This design is based on using a bulb with a condenser lens. The light passes from the bulb, through a mirror with a circular area of reflective material removed. It passes through a 1/4 wave retarder that also has a circular area removed. Then it passes through a reflective polarizer (could be film attached directly to the fresnel, although I like the idea of a sheet of UV glass.

Properly polarized light will pass directly through all of these and illuminate the LCD panel. The rest of the light will be relfected back through the retarder, be re-oriented 1/4 wave, then bounce of the mirror, be re-oriented a further 1/4 wave, then pass through the polarizing filter, illuminating the LCD.

Now the big problem: Where do we get the 1/4 wave and 90 degree reflective polarizing films?

[Hezz]

Honukele,

It's nice to see someone else trying to impliment a light recycler. I have looked at your design and it is quite ingenious. It should quite well and the beauty of it is that it can be easily implimented.

I would make sure that the entire enclosure from the first mirror to the polarizing reflector is lined with highly reflective material on all sides because you will get light bouncing around at all angles and you want to trap all of the light in this area until it can exit with the correct polarization state.

You could also completely surround the light source with reflective material as a lot of stray light goes off to the sides. With your system you could also eventually recycle some of this light if you made the first mirror reflective on both sides. The stray light would bounce around in the first light chamber until it found it's way through the hole and the condenser lens.

Also, as you probably already know make sure to use a spherical reflector behind the light source. In theory you could have light bouncing back into the reflector and out again to eventually be properly polarized.


3M makes some reflective polarizing films called vikitu. They have a web site. Search for Vikitu films.

I found at least one company that makes 1/4 wave plate thin film retarders but I lost the link. If I find it again I will post it here.

Good work and best wishes on your project.

Hezz

[jackson6_4]

All 17 and 15 LCD can do 16:9 Count the Pix, or read the service Data, Refrect Light it have been use it on the market for over 20Years, u can use 2 mirrow in 90 Degree angle, or use Curve mirror, use bigger Lens better then Bigger light, My Triplet 8inch
and weight 6lbs ,

[Hezz]

Honukele,

Here is a company I found that makes 1/4 wave retarder films.

http://www.optigrafix.com/qwgrade.htm

Hezz

[Hezz]

In keeping with my goal as a roll around projector I went and bought a old used office chair at a thrift store for 10 dollars. I dismantled the chair and I will be using the lower roll around support and screw adjuster to mount the projector frame on. This will give me about 4-5 inches of up and down height adjustment.

Hezz

[Guy Grotke]

This is a great idea since incorrectly polarized light does not get through the LCD panel, and is used in lots of high-end projectors.

But sending all that recycled and re-oriented light just anywhere, does not help: Light has to go through the LCD in a direction that will hit the projection lens, or it adds nothing to the image. So lining the light chamber with reflective material is a waste of time and money. In fact it might actually harm the resolution of the image. Lots of lenses get much sharper when a stop aperature is added to limit the light to rays going in the right directions near the center of the lens.

I think you might want to think about a design that uses an elliptical reflector with a positive lens just past the focal point to make a small parallel beam. Then you can use a polarized reflector to send the incorrectly polarized light to another path for re-orientation. Then add it back to the main path with a beam splitter prism. Then a lens could spread it to a fresnel for the LCD.