SLM guy here!

Topics not fitting anywhere else.
jplee
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SLM guy here!

Post by jplee » Sat Mar 24, 2018 7:53 pm

Found this cool forum and just saying hi! I hope I could be of help to some of the spatial light modulator users. :D
I've also been developing a freeware SLM tool on my site which might be interesting to some of you.

https://slmtoolbox.neocities.org/

My use of SLM is not frequent anymore so I wish to learn the type of holography in this forum.

Thanks!
JP Lee

lobaz
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Location: Pilsen, Czech Republic

Re: SLM guy here!

Post by lobaz » Thu Apr 05, 2018 3:46 pm

Looks very nice!
I have to try it in real once I find some free time... I have been playing with it for a while just on the screen, watching the phase pattern as is.

Petr

jplee
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Re: SLM guy here!

Post by jplee » Fri Apr 13, 2018 7:42 am

Thanks! :D

Please let me know if any features would be interesting, or if there bugs. Still adding experimental features. SLMs are normally too expensive outside university labs, but I saw papers that hacked video display projectors to modulate phase.

jrburns47
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Location: Oyster Bay, NY

Re: SLM guy here!

Post by jrburns47 » Fri Apr 13, 2018 9:05 am

Thanks for interesting link. Can you post papers re hacked video projectors?

lobaz
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Re: SLM guy here!

Post by lobaz » Thu Apr 19, 2018 6:30 am

I don't recall any particular paper on projector hacking. Anyway, I don't think you find anything interesting inside. Any SLM inside any projector can be used. The biggest obstacle is how to disassemble the projector and keep it running - the projectors usually check if there is a lamp, if the lamp is on, if the fans are on, if the temperature is in expected range and so on. Every projector treats is differently, no article would help you unless you use exactly the same model.
Many years ago I tried to hack an old DLP projector. I succeded to cheat all security checks, but as I am not an electrician, the result was too uncomfortable to use. A few months later I discovered Cambridge Correlators and their SDE1024 Low Cost Spatial Light Modulator (see https://www.cambridgecorrelators.com/). As the price of the ready-to-use SLM was similar to prices of the projectors at that time, there was no reason to continue with hacking any more.

HoloM
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Re: SLM guy here!

Post by HoloM » Thu Apr 26, 2018 2:34 pm

Hi Peter,
do you know the price of the SLM?
Thanks

lobaz
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Joined: Mon Jan 12, 2015 6:08 am
Location: Pilsen, Czech Republic

Re: SLM guy here!

Post by lobaz » Mon Apr 30, 2018 4:30 am

do you know the price of the SLM?
Hard to tell, I bought a complete optical system with SLM, camera, optomechanics etc., and I got price for the whole set. I guess that SLM alone was about 1000 EUR or less. It was in 2011.

Petr

jplee
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Re: SLM guy here!

Post by jplee » Wed May 02, 2018 2:51 pm

Hi, I think it is this:

Operational modes of a ferroelectric LCoS modulator
https://www.uv.es/gpoei/articulos/(2009 ... atings.pdf

Its quite technical maths though, but basically by modifying the polarization, a cheaper (binary) display projector can function for phase modulation instead of amp modulation. Note however that different techniques are used in different projectors, so taking apart a random display projector will not work if it is not LCOS (liquid crystal on silicon). There are types that use micro mirrors (DMD) and those with color filter built in to the SLM and these might not operate for phase modulation even when modified. A helpful indicator is if the projector intrenally has 3 (r,g,b) light sources, instead of 1 white bulb, but DMD can also have 3 sources...

For papers, I think important keywords are FLCOS (F = ferroelectric) and binary. Cheaper modded display projectors only have 2 phase levels (normally 0, pi) unlike research SLMs that normally have 256 phase levels.

This is a clearer example of a binary LCOS for phase modulation, but I'm not sure if it is from a display projector
"Wavelength-compensated color Fourier diffractive optical elements using a ferroelectric liquid crystal on silicon display and a color-filter wheel"
https://www.osapublishing.org/ao/abstra ... o-48-5-911 (not open access)

I recall research SLMs are around 10,000 to 20,000 eur, so normally only universities or companies have them.

lobaz
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Re: SLM guy here!

Post by lobaz » Thu May 03, 2018 11:13 am

Anyway, for basic experiments in holography, even binary amplitude modulation works well. Applications that require high diffraction efficiency and low noise should probably get a "research slm" jplee talks about.

jplee
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Re: SLM guy here!

Post by jplee » Wed Sep 26, 2018 5:21 pm

sorry for long break...(though I predict this might be the trend with hobby software development :? )

just updated the software so that final output can be binary mode to better match hacked projector SLMs. (and other features biologists might need :ugeek: )

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