Thumper,
As you may have read, my hopes for acceptable blacks from the new DLP's were dashed after seeing the Sharp 9000.
In a previous thread you described how you improved contrast on an LCD by adding polarizer plates: "Together they cut the brightness 40% but did yield better contrast."
How much better? Any guess what contrast and lumens you could end up with if you added polarizers to, say, the Sanyo 21/30/45? I'd be willing to give up more than half the light for 1500 or 2000:1 CR.
Does this have anything to do with the LCD's mechanism of stopping light transmission?
Back to DLP:
1) I was in the process of sketching up some light trap designs we've used in our instruments (I do optomechanical design) when I saw in a post yesterday that TI uses a cone for this purpose, which is a good approach. Light entering reflects back and forth between opposite walls, so if you have 10% reflectivity and 6 bounces before the ray exits, its intensity is reduced by a factor of one million. Depending on its design and implememntation, this might not be worth trying to improve. What's your opinion on this? If you think it could be improved, I'll send you what I have.
2) Someone else mentioned light scattering by the dimples in the center of the mirrors. This sounds like it could be the biggest problem and may be why a seemingly paltry increase from 10 deg tilt to 12 deg may be worthwhile, by steering more of the scattered light away from the lens. What do you think?
3) Then there's the basic quality of the mirrors themselves. If they're not very flat and smooth, they will scatter a percentage of any incident light in all directions.
Here's a thought on reconfiguring the light engine: Tilt the DMD to increase the reflectivity, which is what happens as the incident and reflected light rays move away from normal (even a piece of wood looks mirror smooth at a glancing angle).
Taking this further, if you tilt the DMD by 41.4 deg about the horizontal image axis, when you look through the lens, the DMD now has an AR of 16:9 (cos 41.4 = .75). This requires a radical mechanical redesign, because to keep the light exiting straight out through the lens, the incident light has to come almost directly from the side (81.8 deg from the exiting light).
I don't know if this would worsen or improve scattering from the dimples.
Thumper, do you know if the TI site has any actual pictures or mechanical dwgs of the light engine?
Thanks
------------------
Noah
As you may have read, my hopes for acceptable blacks from the new DLP's were dashed after seeing the Sharp 9000.
In a previous thread you described how you improved contrast on an LCD by adding polarizer plates: "Together they cut the brightness 40% but did yield better contrast."
How much better? Any guess what contrast and lumens you could end up with if you added polarizers to, say, the Sanyo 21/30/45? I'd be willing to give up more than half the light for 1500 or 2000:1 CR.
Does this have anything to do with the LCD's mechanism of stopping light transmission?
Back to DLP:
1) I was in the process of sketching up some light trap designs we've used in our instruments (I do optomechanical design) when I saw in a post yesterday that TI uses a cone for this purpose, which is a good approach. Light entering reflects back and forth between opposite walls, so if you have 10% reflectivity and 6 bounces before the ray exits, its intensity is reduced by a factor of one million. Depending on its design and implememntation, this might not be worth trying to improve. What's your opinion on this? If you think it could be improved, I'll send you what I have.
2) Someone else mentioned light scattering by the dimples in the center of the mirrors. This sounds like it could be the biggest problem and may be why a seemingly paltry increase from 10 deg tilt to 12 deg may be worthwhile, by steering more of the scattered light away from the lens. What do you think?
3) Then there's the basic quality of the mirrors themselves. If they're not very flat and smooth, they will scatter a percentage of any incident light in all directions.
Here's a thought on reconfiguring the light engine: Tilt the DMD to increase the reflectivity, which is what happens as the incident and reflected light rays move away from normal (even a piece of wood looks mirror smooth at a glancing angle).
Taking this further, if you tilt the DMD by 41.4 deg about the horizontal image axis, when you look through the lens, the DMD now has an AR of 16:9 (cos 41.4 = .75). This requires a radical mechanical redesign, because to keep the light exiting straight out through the lens, the incident light has to come almost directly from the side (81.8 deg from the exiting light).
I don't know if this would worsen or improve scattering from the dimples.
Thumper, do you know if the TI site has any actual pictures or mechanical dwgs of the light engine?
Thanks
------------------
Noah