Mystery objective with crosshairs/fixture on front lens
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Mystery objective with crosshairs/fixture on front lens
I recently came across this objective while looking at a disused GE DeltaVision OMX TIRF-SIM super-resolution microscope.
Has anyone seen this before and do you know what it is? It has no labels that I can see. It has a crosshair that appears to be on the recessed front lens, and a thin translucent squarish thing that seems to be affixed on the front lens and has very faint stripes when held to the light. Is it some sort of calibration device related to the laser and/or the SIM grating?
Unfortunately the OMX was completely inoperational and there was no other microscope available to screw on the objective to take a look. Unfortunately I didn't bring my loupe.
There's a slight possibility that this objective has nothing to do with the OMX, but it was sitting near the nosepiece although it wasn't screwed in.
Has anyone seen this before and do you know what it is? It has no labels that I can see. It has a crosshair that appears to be on the recessed front lens, and a thin translucent squarish thing that seems to be affixed on the front lens and has very faint stripes when held to the light. Is it some sort of calibration device related to the laser and/or the SIM grating?
Unfortunately the OMX was completely inoperational and there was no other microscope available to screw on the objective to take a look. Unfortunately I didn't bring my loupe.
There's a slight possibility that this objective has nothing to do with the OMX, but it was sitting near the nosepiece although it wasn't screwed in.
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Re: Mystery objective with crosshairs/fixture on front lens
I wonder if the faint stripes you mention could be some sort of diffraction grating? No idea what it might be used for.
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Re: Mystery objective with crosshairs/fixture on front lens
Maybe an interferometer objective?
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Re: Mystery objective with crosshairs/fixture on front lens
Thank you all for your inputs! I think it is probably an interferometer objective as Scarodactyl suggested. It looks like a Mirau-type objective as shown in Figure 5 at https://www.microscopyu.com/microscopy- ... rferometry
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Re: Mystery objective with crosshairs/fixture on front lens
You'd need coaxial epi illumination to use it. Great for detecting vibrations as they will be dramatically illustrated in the interference figure. I could never get my reference surface level enough to get a bullseye with one.
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Re: Mystery objective with crosshairs/fixture on front lens
Thanks for the additional information. It does seem to me that this kind of objective was initially developed for measuring the topography of microscopic surfaces but it turns out to be very useful for detecting external vibrations affecting a microscope as well.
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Re: Mystery objective with crosshairs/fixture on front lens
I notice that the square patch stuck on the front lens is translucent and doesn't look like a mirror, while the Mirau objective described in the link I gave earlier (https://www.microscopyu.com/microscopy- ... rferometry fig. 5) shows and labels it as a mirror that reflects all of the light. And my objective doesn't seem to have the half-mirror in front of the front lens that is shown with the Mirau objective, although the half-mirror might have been a separate component. Maybe it's a design variation.
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Re: Mystery objective with crosshairs/fixture on front lens
There are a couple types. Maybe it is a Michelson(sp?). Many seem to add an external attachment onto an existing objective (plus maybe an aperture in the back) while Nikon sells some that are built in to the objective. Both worked the same when I tried them.