DLPDLCR4710EVM-G2: Color fringes with projection lens removed

Hello Cher,

Did the projection look correct before removing the optics? It will be required to use projection optics in order to obtain a good image.

Thanks,
Kyle

Hi Cherlyn,

Is this an image directly of the DMD? Or are there other optics in front of the DMD as well?

Thanks,
Kyle

Directly of the DMD. No other optics in front. Thanks Kyle!

Hi Cherlyn,

Please share the picture of the set-up. We needs to get understanding of what you are looking into.

Normally there is TIR prism infront of DMD. Please conform are you taking picture without removing Prism.

In addition , the image should taken with camera focus on ON pupil.

Thanks,
Navneet

Hi Navneet, we did not remove the prism. Here are photos of our set up. Thanks! -cher

Untitled-1 copy.pdf

Hi Cher,
The artifacts in the image for the following two reasons:

1. Camera image capture is not in sync with color refresh of the DMD. It is causing color fringes in the image. The DMD mirrors are modulated to create a gray value . Therefore you would notice similar effect in the monochrome image too. In addition, when you focus the camera directly on to DMD, the light intensity is too high and camera reduces exposure time to prevent saturation. Short exposure also makes this effect visible. This will not be true when projection lens is mounted.

2. The camera is also capturing flat-state and off-sate light. In a projection lens these stray lights are blocked by an aperture.

I hope this explain the image artifact you are observing.

regards,
Vivek

Hi Vivek, thanks for replying. 

1. There were color fringes even when we simply projected onto a white screen and looked with our naked eyes without a camera. 

2. We could see in full grayscale, so it was't just flat and off states light.

Besides, we found (with another DMD) that putting a diffuser in the illumination path before the DMD removes the fringes. Is there any way to do the same for this projector? 

Thanks! -cher

1. There were color fringes even when we simply projected onto a white screen and looked with our naked eyes without a camera.

2. We could see in full grayscale, so it was't just flat and off states light.

Besides, we found (with another DMD) that putting a diffuser in the illumination path before the DMD removes the fringes. Is there any way to do the same for this projector?

Hi Cher,
Your earlier message mentioned that image look good before lens were removed.
One more clarification- What are you referring by "color fringes". I meant the vertical bars in the active area.

regards,
Vivek

Yes Vivek. The image was good before the lens was removed.
Then we removed the lens, replaced it for our own and the color fringes showed up when we projected onto a screen.
It was not a problem with our lens or optical set up. There were fringes on the DMD (as shown in the picture above) even without any lens.
Color fringes refer to the vertical stripes.

Next thing we did was to recreate the same in another projector. Then, we stuck a diffuser in between illumination and the DMD, and problem solved. So we are wondering if there's a way to do the same for this model (i.e., dissemble or open up the light engine and put in a diffuser).

Thanks!
cher

Hi Cher,
I need more information to understand the problem. How does the image look if you re-install the original projection lens of EVM?

What projector were using using in second experiment with diffuser? Could you please share mor detail about what location diffuser was placed between illumination and DMD?

regards,
Vivek