yep i placed the lasers at each corner and yepp it’s 4:3.

Hey progen i had a question are your lasers sitting on top of the acrylic or are they parallel to it so that the beam is exactly on the surface. cause if they are sitting on the lasers dont you get blobs before you touch your screen?

actually i thought about this question, Progen has a plastic(or steel) frame to cover the lasers, you could left about 1mm gap between the frame and glass(acrylic), thus the extra light could be cut off, and you have a perfect laser surface, i’m trying to do this.
@Progen, thanks for your reply, and for 20mw lasers, do you think it’s too much bright? i compared my 10mw with 20mw, 20mw get a very bright blob, and when my 5 fingers come close, the 5 blobs easily became 1 big blobs and the camera can’t distinguish the 5, i’m using Philips SPC900 and i have a Firefly MV B/W, but i didn’t try it.

Taha - 07 September 2008 10:31 AM

Hey progen i had a question are your lasers sitting on top of the acrylic or are they parallel to it so that the beam is exactly on the surface. cause if they are sitting on the lasers dont you get blobs before you touch your screen?

yepp, xiehuangdouhua u almost right.  actually i have 2 sheets of glass each 5mm thick.  the top surface is actually smaller in size than the lower surface.  my lasers are mounted on the lower surface and thus i am able to leave a 1mm gap between the top surface and the laser beam.  hope that doesn’t sound too confusing....

i am using 20mW lasers because i have a rosco as the projection screen, and the rosco cuts out a significant amount of IR from the camera. moreover, i am also able to adjust the aperture of the lens of my firefly if the blobs are too bright.

Ahh makes sense now… cause i’m working lasers on my new setup and it looked kinda odd for you to have your lasers on top… btw what lens are you using with the firefly?

the lens? hmm...thought i had mentioned it in the update on the first post.  anyway, it’s a 1.2mm lens.

no no i meant whos the manufacturer of the lens? what company?

the lens is from Avenir and opps....i made a mistake. it’s 2.8mm not 1.2mm.