Re: Dichroic mirror double reflections issue

Posted by Craig Brideau on
URL: http://confocal-microscopy-list.275.s1.nabble.com/Dichroic-mirror-double-reflections-issue-tp7584577p7584584.html

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This is an issue with any plate beamsplitter. The two possible solutions
are to AR-coat the non-working side, or have the working and back surface
be non-parallel. Some designs will have a slight wedge of a degree or so
between front and back surfaces to reduce these ghost reflections from the
non-working surface.

Happy New Year!
Craig Brideau


On Thu, Dec 31, 2015 at 9:16 AM, Yan, Lu <[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 Sripad,
>
> I am not sure if it has the AR coating on the other side. But I am now
> getting help from the vendor. Hopefully it will solved soon. I am using it
> with 45 degree incidence.
>
> Happy New Year!
>
> Lu
>
> -----------------------------------------------------
> Lu Yan
> Nanostructured Fibers and Nonlinear Optics Laboratory
> Electrical and Computer Engineering
> Boston University
> 8 St. Mary St., Boston, MA, 02215
> 617.353.0286 (office) | 617.358.5917 (lab)
> [hidden email]
> -----------------------------------------------------
>
> On Wed, Dec 30, 2015 at 6:04 PM, Sripad Ram <[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 Yan,
> > The issue sounds like the dichroic does not have an anti-reflection
> coating
> > on the non-reflective side. From the URL it was not clear if the optic
> has
> > the AR coating. Also are you using the dichroic at 45 degree incidence.
> >
> > HTH
> >
> > Sripad
> >
> > On Wed, Dec 30, 2015 at 10:05 AM, Yan, Lu <[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 there,
> > >
> > > I recently bought a dichroic mirror from Chroma (2mm thick reflecting
> > > fluorescence,
> > > https://www.chroma.com/products/custom-inventory/nc302987-zt670dcrb)
> for
> > > our confocal fluorescence microscopy setup. But I found that with the
> > > reflective side oriented correctly, at the reflection band, the
> reflected
> > > beams seemed splitting into two and partially overlapping with each
> other
> > > (ghost image?). This happens at a wide range of incident angles, and
> as I
> > > rotated the dichroic (changing the angle), the "overlapped" reflection
> > > alternated between partially overlapping and two distinct separated
> (by a
> > > dark line in the middle) half circular beams.
> > >
> > > Images of single fluorescence bead also showed 'side lobes'. So I was
> > > wondering if anyone has experience on how to eliminate such effect? Is
> > this
> > > common for dichroics? Or it is specific for the one I have and I should
> > get
> > > another one?
> > >
> > > Thank you very much in advance, and I wish you all Happy New Year!
> > >
> > > Lu
> > > -----------------------------------------------------
> > > Lu Yan
> > > Nanostructured Fibers and Nonlinear Optics Laboratory
> > > Electrical and Computer Engineering
> > > Boston University
> > > 8 St. Mary St., Boston, MA, 02215
> > > 617.353.0286 (office) | 617.358.5917 (lab)
> > > [hidden email]
> > > -----------------------------------------------------
> > >
> >
>