Anaglyphic 3D with Lasers

[kecked]

Did you see the little 1024x768 (720p-ish) SLM I built at SELEM? I had it on my optical breadboard . I've worked with some stupid-expensive DMD-based SLMs (they're the only game in town for UV wavelengths), and that inspired an active investigation into the lowest quality (read: cheapest) LCoS panels from which I can successfully eek out a simple HOE like a zone plate. I WISH you could pull this off for $30 ...it's realistically more like low $$$ hundreds.

SLMs aren't new, but there's been a recent explosion in new applications for them. They used to be popular for automatic optical inspection and some niche high-speed computation systems (<cough> terrain-following guidance systems <cough>), but now they're driving everything from resin-based 3D printers, HUDs and VR devices, optical computing, and even digital inter-cavity beam shape control. At a super basic level, overhead transparencies and film negatives or slides can be considered static spatial light modulators. LCoS panels are convenient because of their polarization properties, but there are other types of electronic SLMs such as transmission-mode TN LCD and digital mirror array devices. I vaguely recall some researchers also doing exotic things like using surface acoustic waves to create SLMs with engineered metamaterials. Optically-addressable SLMs also exist.

The basic input "image" for your wavefront is the 2D Fourier transform of your desired output image. Computing the SLM input for
arbitrary phase and/or amplitude-based images is trivial, but the materials and build quality have a huge effect on ability to accurately form a wavefront and usually require blemish-mapping for defect correction. That necessitates access to a setup for characterizing the SLM. The special sauce in a lot of commercial packages is the extremely low-defect panel and some really good correction algorithms. One disadvantage of an SLM-based holographic image is the need to focus it onto a plane for viewing. You need some serious resolution to produce anything approaching the quality of a film-based hologram. However, low-res is still very cool for making things like optical tweezers and simple structured light.

nope missed it. All I’m doing is making a binary grating so I think I’m just going to use a grating and take the first order through a spatial. It’s for a shg microscope. I literally heard of them two days ago. Really cool tech.

so can’t I just open an lcos projector and feed it Video? 10k is absurd for a binary grating. However they might mean a radial grating in which case this won’t replace with a regular grating. I saw replacement lcos on ebay for 30.00

yes I see now all the cheap ones are low resolution like in some cases sub vga.

[CountFunkula]

nope missed it. All I’m doing is making a binary grating so I think I’m just going to use a grating and take the first order through a spatial. It’s for a shg microscope. I literally heard of them two days ago. Really cool tech.

so can’t I just open an lcos projector and feed it Video? 10k is absurd for a binary grating. However they might mean a radial grating in which case this won’t replace with a regular grating. I saw replacement lcos on ebay for 30.00

yes I see now all the cheap ones are low resolution like in some cases sub vga.

Yes- you can gut the optical path of an lcos projector and use it to power and host the now-naked SLM. More than a few people have done this as part of DIY photolithography stepper builds. Replace the lamp with your exposure source (if it’s UV, you’ll have to use a DMD projector), focus it into a microscope, and feed it an image of your mask and you’ve got the core of a basic home photolithography setup.

There are replacement DMD and LCoS panels available for a few tens of $, but the drive electronics are where it gets pricy unless you’ve got mass manufacture on your side. The electronics between the video source and panel convert the image feed to a high speed parallel interface with drive waveforms that are often tailored to a given panel.

[masterpj]

ld2000 has an anaglyph setting which is hidden in the ini files which could generate 2 images in realtime if your frames were made with depth
There is another way to do it today which is using 2 3ds max cameras spaced at the right angle and rendering 2 sequences of the same scene and simply just changing the entire scenes color for each eye.

However anaglyph comes at such a huge cost of losing practically all your color options... great and cheap way of making 2 images without needing an intensive sync though!

[marksmartus]

Hi all.
After not playing with the laser for a long time, I hooked the Unity Raw 1.7 up this weekend and got Reaktor controlling it. This is a lot better than the Laserworld projector I was using. Varying the voltage on the color lines actually DOES make the colors get brighter and dimmer. LOL. The thing is just a lot better built. It still works fine to just wire the outputs of my MOTU Ultralight audio interface directly to the ILDA input connector on the projector. This is currently on a protoboard; I am going to build a box that is a lot more robust so I don't have another embarrassment like last April! I hope to add the capability of patching in control voltages from an external analog synth, or processing external voltages through Reaktor first, which could make some cool effects. I'll keep you posted.

Mark

[marksmartus]

Hey, the forum is back up! Did someone forget to pay their domain registration fee? LOL I've done that before. One day your web site just vanishes.

Here is a short video of the new laser doing 3D stuff.

http://www.marksmart.net/gearhack/Laser/Laser01.mp4

What's weird is that if I watch this video within Chrome, I can't see both the red and green at the same time, but if I download the file and watch it with VLC media player, I can. Maybe Chrome's player plays at a slower frame rate. So far I haven't figured out how to make a video with the right colors to get a 3D effect when you watch it.