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Dear sir, If my dmd has a tilted angle of +/-12 degree, which has a f-number of 2.4. What if I put a lens before the dmd which f-number is 2 (smaller) or 3 (bigger) ??? what would happen??? what would happen to the contrast if I used different f-number of lens? and what is the specifications of 0.55 xga dc2 dmd? thanks
A belated Welcome to the DLP section of the TI E2E Community.
I am very sorry that your question appears to have gotten overlooked until now.
Please look at the attached document. It should answer quite a few of your questions. If you still have questions after reading it please post back.
thanks for your reply. I have a question about 0.55''.
I think it means 0.55 inch in diagonal line. And it is a 4:3 rectangle.
So that makes the size of the dmd, length= 0.55 * 25.4(mm)*(4/5)=11.176 mm height= 0.55 * 25.4(mm)*(3/5)=8.382 mm
Also I know the gap between the pixels is 1 um, and the pitch between the pixels is 10.8 um
But what's the length of one pixel?? And are these pixels square?
If you are refering to the 0.55" XGA (1024x768) DMD, here are the dimensions. The DMD is 0.55 inches across diagonally. The mirrors are 10.8um in width and they are squared. The width of the active mirror array is 11.059mm and the height of active mirror array is 8.294mm.
WYA is correct the mirrors are square. The pixel pitch is 10.8 um and the gap is approximately 1 um. This makes the actual mirrors approximately 10.8 um minus ~1 um.
I hope that helps.
Thanks for your help.
But I still have a question. When DMD is not activated, are these micro mirror set flat (not tilt +/- 12 degree)??? If this is the case, it should be convenient to measure the pixel size and the gap.
Besides, as you mentioned, the gap is approximately 1 um. How is this size measured (measured when set flat or tilt)??
The gap references when the mirrors are nominally flat.
When the mirrors are powered they are actually landed to the surface at + or - 12 degrees. When no power is applied the mirrors return to their rest position which is approximately flat. However the flat state cannot be "set". When the device is powered there are only two states available + and - 12 degrees.
One thing that I wanna make sure is that what is the width of one pixel of the DMD?
Is it 10.8 um or 9.8 um (10.8-1)? Because these two is very differnt.
WYA replied by "The mirrors are 10.8um in width. The width of the active mirror array is 11.059mm"
But you replied by "pixel pitch is 10.8"
The "pixel pitch" refers to the distance from the center of one mirror to the center of an adjacent mirror. This value is 10.8 um.
The size of the individual mirror is approximately 9.8 microns on each edge. The gap size can have some variation. This is why I said the gap is approximately 1 um.
I hope this information helps.
I have a question, is the 0.7''XGA DMD the same as 0.55''? The "pixel pitch" refers to the distance from the center of one mirror to the center of an adjacent mirror, so the "pixel pitch" is 13.68 um? Or it is 14um? Because in my experiment "14um" is appropriate.
Welcome to the DLP section of the TI E2E community.
These device have the same number of pixels (XGA - 1024 x 768) but the "pixel pitch" is not the same. The 0.7" XGA DMD is a 13.68 um pixel pitch device and the 0.55" XGA DMD is a 10.8 um pixel pitch device.
I hope this helps.
thank you for your reply for my question,it helps.
i have another question now.Recently,i am on my experience of DMD diffraction pattern.But to my surprise,for the same model 10.8um,12° switch angle DMD,it has two different diffraction patterns,one ,the energy concentrate on the middle point, which means there is only one point very bright . the other, the energe is distributed by the middle two points,which means there are two points very bright. I can not find the reasons,is there any other parameters decide the diffraction pattern besides 'pixel pitch' and 'switch angle'?
ps:i use 405nm wavelength laser
Would it be possible to attach an image of what you are seeing. It sounds like you may be seeing reflections from the window of the intial incident beam, but I would like to see an image of it to better understand.
as you see,for the same conditions the diffraction pattern is different,why?
ps:the same conditions includes:incident wavelength(405nm),incident angle(24°),pixel pitch(10.8um),switch angle(12°)
First, excellent pictures! That is exactly what I was wanting to see
Now let me ask a couple of questions:
first, let me answer your two questions:
1. the two patterns are parallel to the DMD surface.
2. all the mirrors of DMD are on the "ON" state.
then let me show you my experiment schematic diagram:
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