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-tp7587097p7587111.html

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Hi Adam,
it's just a cartoon...
Ray-optical properties of a thin lens are simple. The rules are (1) a bundle
of parallel rays will be focused by the lens to a spot somewhere on the
focal plane (and vice versa), and (2) rays passing through the center of a
thin lens continue un-deviated.
So clearly, to achieve spatial offset in the focal plane the rays of the
individual channels have to impinge on the lens from different angles. The
angles will be fairly close to parallel with the optical axis for f=200mm
lens.

It really may be more difficult than it seems, I recommend using some
raytracing software so you get an idea. Or google for "telecentric system"
or "4f system".

Note also, that real lenses are not thin lenses and the spectral properties
of the dichroics depend on the incidence angle...
You may also find that a more complicated design with individual focusing
lenses gives you more flexibility in alignment...

See e.g. this cartoon:

https://www.cairn-research.co.uk/wp-content/uploads/2015/12/Optosplit-III-LS
-Image-Splitter1.jpg

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: 2. 8. 2017 16:03:11
Předmět: Re: Advice on building multi-channel image splitter
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Thanks everyone for the input. Optics wise, is it important to ensure that
the separated images are incident on the final tube lens parallel to the
optical axis? And simply shifted laterally to achieve the spatial offsets?
As in this cartoon illustration: http://www.andor.com/scientific-cameras/
multi-wavelength-imaging/optosplit-iii#prettyPhoto[pi_gal]/1/

Or is generating the spatial offsets using a combination of tilt/tip of the
dichroics and/or mirrors also adequate? In this case the different beam
paths might not all be perfectly parallel to the optical axis.

I am just thinking through my head the alignment/optimization of our home
built image splitter.

Thanks again,
Adam
"