Spatial Filtering Video

[planters]

I uploaded a video to YouTube a couple of days ago that goes through the set up and benefits of spatial filtering. Now, I am able to log into PL in order to link to it. I hope it proves useful.

http://www.youtube.com/watch?v=A5sjyEGFOhE

[Stiffler]

I watched the video yesterday, thanks for taking the time to make it:-)

I do have a question: Can spatial filtering be used after the beams are combined, or does each wavelength need it's own filter?

[absolom7691]

Thank you, Eric. This was extremely informative! In using this setup, what kind of exit beam size are you looking at just after the 200mm lens? Also what is your estimated divergence?

[planters]

You can certainly filter multiple diode modules just as well as a single diode because they both converge to a single point at the focus. Running different colors through a single filter should work if you use reasonably long FL lenses or certainly, achromatic lenses. You would loose the ability to custom size each colors beam size for the scanners. I think the benefit of the filtering would still be worth it even if the process is a little compromised in order to simplify the beam lay out.

[planters]

Thank you, Eric. This was extremely informative! In using this setup, what kind of exit beam size are you looking at just after the 200mm lens? Also what is your estimated divergence?

I am using a 100mm/200mm lens pair for the convenience of a spread out lay out for the video. You can use the same ratio ie say 50mm/100mm etc with the exact same performance. You will just need to be a little more (twice) careful with the blade positioning. With a 4.5mm square exit beam, as in my projectors, I get a 1mrad x 0.5mrad divergence. I am about there in the video and I clearly haven't taken any care with fine tuning each optical element.

[logsquared]

Thanks for posting. Great video.

Have you taken power measurements before and after? Curious to how much actual power is in the "wings"

[planters]

Have you taken power measurements before and after? Curious to how much actual power is in the "wings"

No I haven't, but there is zero loss in the central spot. My guess is the wings contain less than 10% of the light.

[absolom7691]

With the large, high-power layouts that you normally build and how cleanly this shapes the beam, I can now see why you love these P73's so much!

[planters]

I do! But, the older G71's are even better with about 2/3 the divergence and about 2/3 the power (about 1W each). I have these in a couple of projectors that are green output limited.

[polishedball]

Thanks! Lens will be here tomorrow.

Edit couldn't wait just grabbed 2 odd lens out of my box. Couldn't nicely adjust razors as nothing was screwed together, but wow. This works awesome.