Re: Advice on building multi-channel image splitter

Posted by Zdenek Svindrych-2 on
URL: http://confocal-microscopy-list.275.s1.nabble.com/Advice-on-building-multi-channel-image-splitter-tp7587097p7587100.html

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Hi Adam,
generally, you can split and combine either in the "aperture space"
(infinity space) or "image space". Both have some interesting properties,
pros and cons.

The (very common) Andor approach (splitting and combining in the infinity
space) means that the different "channels" arrive at the sensor from
different angles. Possibly important implications are:

Vignetting: with zoom 1 optics the beam size at your combining mirrors (that
are close to the aperture plane) is the same as the back focal plane (BFP)
aperture of the objective lens. Away from the aperture plane the beam will
likely be even bigger. You want to make sure you are not blocking part of
that beam by other mirrors. This would reduce both intensity AND
resolution...

Aberrations: apart from the possible aberrations introduced by the
dichroics, the last lens will be critical, too. The aperture of this lens
will be much higher than that of the rest of the optics, by a factor of 2-4
(the number of channels) or even more, depending how close you can get the
individual beams when combining (D-mirrors will be helpful here). It may
happen that a doublet (even at f = 180 mm) may not perform diffraction-
limited-ly. Also, you may find that 1-inch optics is just too small,
especially with big CMOS chips.

Note: the flat dichroics are really flat when Semrock mounts them into their
TIRF cubes. You need to be careful (or ask Semrock) if you want to mount
them yourself...

As mentioned before, you will need fine adjustment mounts for both the
dichroics and the combining mirrors to get both the aperture and the field
exactly where you want them.

Good luck!

Best, zdenek
--
Zdenek Svindrych, Ph.D.
W.M. Keck Center for Cellular Imaging (PLSB 003)
Department of Biology,University of Virginia
409 McCormick Rd, Charlottesville, VA-22904
http://www.kcci.virginia.edu/
tel: [phone]

---------- Původní e-mail ----------
Od: Adam Glaser <[hidden email]>
Komu: [hidden email]
Datum: 31. 7. 2017 16:11:43
Předmět: Advice on building multi-channel image splitter
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Hello everyone,

I was wondering if anyone could offer advice on building an in-house image
splitter for microscopy.

We are hoping to build one to split a rectangular ROI vertically into 2-4
colors. The design seems straightforward, similar to the schematic of the
Optosplit by Andor http://www.andor.com/scientific-cameras/multi-wavelength-
imaging/optosplit-iii#prettyPhoto[pi_gal]/1/.

Are there any non-obvious factors to consider when building? We will be
using 2 identical tube lenses, the first to image an adjustable slit for
creating the cropped rectangular ROI, the second to re-focus onto our sCMOS
camera, and super resolution imaging grade dichroics from Semrock.

Thanks,
Adam
"