http://confocal-microscopy-list.275.s1.nabble.com/1W-405-source-tp7591310p7591329.html
array as their homogenizer. If you remove it, you do get a bit more power
force approach with the 10W LED. With a 10x/0.3 NA objective, the 3W laser
field illuminated. The 10W LED put about 45 mW/mm^2 onto the sample plane
with the whole field being illuminated. For comparison, a xenon arc lamp
plane on the image plane). The only way we found to fix this was to
> *****
> 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 Ben,
>
> I'm glad LEDs work for you. Absolutely, if 10 mW/mm^2 is enough, LEDs are
> the way to go!
> We've used Luminus Phlatlight LEDs in the past, they are much brighter (in
> terms of W/mm^2/sr) than most. But they are also more pricey.
> I'm surprised how much better the LEDs are now, especially in the 400 nm
> range with 1 W optical output from 1 mm^2 chip...
>
> Importantly, there is no reason why a LED-based fluorescence illumination
> system *with* DMD should be dramatically dimmer than *without* it. The
> optical efficiency of a DMD is 70%. Still, even in commercial LED light
> sources most of the light is wasted, as the chips are too big (but it makes
> the optical design easier).
>
> Lasers make things more complicated, but my favorite arrangement -
> multimode fiber shaker and critical illumination - work most of the time.
> The DMD acts as a very poor blazed grating, so it's tricky to make it work
> efficiently, especially with multiple laser wavelengths. But with a 1 W 405
> nm laser you still have plenty of light for photoconversion, photobleaching
> and photodamage experiments.
>
> Finally, I have never heard of microlens homogenizer used together with a
> DMD. All DLP projectors (I've had the pleasure to take apart) use a light
> pipe homogenizer, maybe except for the tiniest ones. I wasn't lucky enough
> to get my hands on a LightCrafter or similar stuff... For microscopy
> equipment, I don't see a reason for a homogenizer (exactly for that same
> reason - the etendue of the source is so much bigger than what the
> objective lens can use).
>
> Best, zdenek
>
>
> On Tue, Sep 22, 2020 at 4:02 PM Benjamin Smith <
>
[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.
> > *****
> >
> > Attaching DMDs to microscopes is actually pretty common in optogenetics
> and
> > retinal research. Here is an image of a DMD coupled into a BX-51 arm in
> > one of the labs I work with using one of the high power LEDs:
> >
https://drive.google.com/file/d/1oFL0CQynji-hmkIDca002IZMmitwtksd/> >
> > In this setup we wanted a high power 450 nm output for optogenetics (>10
> > mW/mm^2 at the sample plane) while still having it usable as a
> fluorescent
> > microscope, so we used a 10W 450 nm LED (the one with the CPU cooler
> > attached) for the high power channel combined with a liquid light guide
> > from a xenon arc lamp for longer wavelengths.
> >
> > Originally we tried a 3W 450 nm laser we bought off of eBay for $50
> (which
> > to our surprise really was 3W optical output), but quickly realized that
> > the vast majority of losses in a DMD are at the microlens array used to
> > make the light uniform across the DMD. Additionally the coherence of the
> > laser caused a strong speckling issue, which we tried to abate with 10m
> of
> > multimode fiber but was still pretty strong. We also had to couple at an
> > odd four degree of freedom offset to try to get as much of the field
> > covered as we could.
> >
> > We then switched to the 10W LED, and since it covers the whole microlens
> > array, the field of illumination was perfectly uniform, and did not
> require
> > any odd 4 degree-of-freedom alignments.
> >
> > One thing to keep in mind is that the DMD array itself is fairly big, so
> as
> > along as the LED die is appreciably smaller than the DMD itself, then the
> > etendue really won't cause a loss in intensity due to coupling, and will
> > only work in your favor to have a more uniform field of illumination.
> > Additionally, since these LEDs are intended to be used with DMDs, some of
> > them even have dies with a 4:3 or 16:9 aspect ratio for even better
> > efficiency.
> >
> > And a quick side note, for anyone who want's to couple a DMD into a
> > microscope, I strongly recommend using the BX-51 arm. It is easy to pull
> > out the lenses, and a Thorlabs SM1 lens tube fits neatly inside with only
> > minor modification. You can also fit a TTL200 tube lens right behind the
> > manual shutter, giving you the perfect spacing to the back focal plane of
> > the objective.
> >
> > Cheers,
> > Ben Smith
> >
> > On Tue, Sep 22, 2020 at 8:57 AM Zdenek Svindrych <
[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 Antonio,
> > >
> > > We used to buy from Dragon lasers (China) many years back, now CNI
> Laser
> > > (again China) seems like a great source (no commercial interest).
> > >
> > > If you want to go super cheap, you can search eBay for laser engraving
> > > modules, some are 405 nm (but mostly 445 nm), you want something like
> > "7W"
> > > at least, as it's the electric input power... And don't stare into the
> > beam
> > > with your remaining eye!
> > >
> > > Andor uses a fiber shaker to homogenize the beam (and critical
> > > illumination, like their Borealis technology) for their Mosaic DMD
> > devices,
> > > but I can't guarantee the amount of light you can couple into a 50 um
> or
> > > 100 um fiber from the eBay laser modules...
> > >
> > > UV LEDs sound cool, but the problem is the coupling efficiency
> (etendue).
> > > If your source is a 1 mm^2 LED chip, you can illuminate 1 mm^2 with a 1
> > NA
> > > objective lens with good efficiency (if you try hard). If you try to
> > focus
> > > the light down to 0.3 mm^2, 90% of the light is lost... And higher
> power
> > > (more LED chips) won't help you get more light trough, only the optics
> > may
> > > be simpler... Of course on top of that another 99% of light is blocked
> if
> > > you only have few DMD pixels "on"...
> > >
> > > I've seen papers where folks bolted a DMD digital projector to a
> > > microscope. Lie this one:
> > >
https://drive.google.com/file/d/1IEfgKvZ0JrCUaaUPdnRFhUzT3phJO-D-/> > >
> > > Best, zdenek
> > >
> > > On Mon, Sep 21, 2020 at 10:11 AM Antonio Jose Pereira <
> > >
[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.
> > > > *****
> > > >
> > > > Dear all,
> > > >
> > > > I'm looking for a 0.5-1W , 405nm, can have many spatial as well as
> > > > longitudinal modes, 405nm laser. This is to feed a photoconversion
> > module
> > > > (Mosaic), a DMD-based system that wastes most power. That's why we
> need
> > > > such high power source.
> > > >
> > > > I appreciate if you could give suggestions on low-budget options,
> which
> > > > I'm failing to find ...
> > > >
> > > > Thank you so much,
> > > > Antonio
> > > >
> > > >
> > > >
> > > > Antonio Pereira
> > > > CID lab
> > > > i3S/IBMC, Universidade do Porto
> > > > Room 001.S2B, +351 22 607 49 59 Ext. 6127
> > > >
> > >
> > >
> > > --
> > > --
> > > Zdenek Svindrych, Ph.D.
> > > Research Scientist - Microscopy 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
> > 195 Life Sciences Addition
> > Berkeley, CA 94720-3200
> > Tel (510) 642-9712
> > Fax (510) 643-6791
> > e-mail:
[hidden email]
> >
> >
>
https://vision.berkeley.edu/faculty/core-grants-nei/core-grant-microscopic-imaging/> >
>
>
> --
> --
> Zdenek Svindrych, Ph.D.
> Research Scientist - Microscopy Imaging Specialist
> Department of Biochemistry and Cell Biology
> Geisel School of Medicine at Dartmouth
>
Benjamin E. Smith, Ph. D.