Re: 2P laser coupled to a DMD?

Posted by Benjamin Smith on
URL: http://confocal-microscopy-list.275.s1.nabble.com/2P-laser-coupled-to-a-DMD-tp7590172p7590175.html

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Are you wanting temporal or spatial non-linearity?  For temporal, it would
be much easier to use a Pockels cell, and you could even drive it using the
analog output on your electrophysiology equipment to get perfect temporal
correlation.  For spatial (as in holographic), as others have said, you
would need an SLM on the focal plane, and likely a second spectral SLM for
temporal encoding to move the probe in the axial domain.  DMDs are actually
pretty terrible at high speed intensity coding because they encode 8-bit
gray scales by sequentially flashing eight binary masks, each representing
one of the eight bits to be encoded.

On Tue, Nov 19, 2019 at 1:52 PM Zdenek Svindrych <[hidden email]> wrote:

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> *****
>
> Hi Gary,
>
> it's certainly not easy :-). If you're thinking about turning just few
> pixels on that would define the locations of photoactivation (so the DMD is
> a mask that is conjugate to the image plane), then, no, this won't work. At
> least not over any reasonable field of view. The throughput would be too
> low and you won't get enough peak power for two-photon absorption to
> manifest.
>
> If you're thinking to encode a diffraction pattern on the DMD that would
> steer your beam (single spot in the image plane at a time), this would
> probably work, but I don't know any commercial product like this, as
> galvo-based steering is more efficient, simpler, cheaper; only quite a bit
> slower. There are vis-laser solutions available commercially, but those use
> LCOS for better efficiency.
>
> From the power-handling point of view, you won't really damage a DMD or
> LCOS SLM with a 1 W average power spread over the full chip. The peak power
> won't matter as it's not focused to a spot on the DMD; the 80-or-so MHz
> pulses just might disturb the electronics behind the pixels in some very
> unfavorable cases.
>
> Best, zdenek
>
> Zdenek Svindrych, Dartmouth College
>
>
> On Tue, Nov 19, 2019 at 3:34 PM Gary Laevsky <[hidden email]>
> wrote:
>
> > *****
> > To join, leave or search the confocal microscopy listserv, go to:
> > http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> > Post images on http://www.imgur.com and include the link in your
> posting.
> > *****
> >
> > Hi All,
> >
> > I THINK this can be done?  DMD that can handle high power and appropriate
> > reflective characteristics for the wavelength.  Or could I do this with
> an
> > SLM?
> >
> > We're looking to do non-linear optogenetic switching.
> >
> > If this is simple, please be gentle.  I'm a biologist ...:)
> >
> > If it is simple, can you please direct me to the appropriate vendor.
> >
> > Thanks in advance.
> >
> > --
> > Best,
> >
> > Gary Laevsky, Ph.D.
> > Director, Confocal Imaging Facility
> > Nikon Center of Excellence
> > Co-Founder, North Atlantic Microscopy Society (NAMS)
> > https://namsmicroscopy.com/
> > Dept. of Molecular Biology
> > Washington Rd.
> > Princeton University
> > Princeton, New Jersey, 08544-1014
> > (O) 609 258 5432
> > (C) 508 507 1310
> >
> > North Atlantic Microscopy Society Spring Meeting at UPENN, April 23,
> 2020.
> >
>
>
> --
> --
> Zdenek Svindrych, Ph.D.
> Research Associate - Imaging Specialist
> Department of Biochemistry and Cell Biology
> Geisel School of Medicine at Dartmouth
>


--
Benjamin E. Smith, Ph. D.
Imaging Specialist, Vision Science
University of California, Berkeley
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