Re: Advice on building multi-channel image splitter

Posted by Craig Brideau on
URL: http://confocal-microscopy-list.275.s1.nabble.com/Advice-on-building-multi-channel-image-splitter-tp7587097p7587110.html

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The parallel image paths must both pass through the same tube lens to be
focused on the CMOS/CCD array. You will want to make sure the two paths
pass on either side of the center of the tube lens to get adequate focusing
onto the array. If the tube lens diameter is too small compared to the
combined width of the beam paths you will see distortion or lateral defocus
from operating too close to the edge of the lens. Alternatively you can use
two separate tube lenses with long working distances (200mm is typical for
a tube lens anyway) and combine them with a dichroic as close to the lenses
as possible. This could lead to slight distortion if the dichroic is of
mediocre quality as you will not be in infinity space when you combine the
two light paths. That said, you can then easily offset one path relative to
the other by translating the position of the dichroic, and the image cast
onto the CMOS/CCD should be flat for both paths with minimal distortion.

Craig

On Wed, Aug 2, 2017 at 2:02 PM, Adam Glaser <[hidden email]> wrote:

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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
>