Re: How to measure objective transmission curves?

Posted by Mark Cannell on
URL: http://confocal-microscopy-list.275.s1.nabble.com/How-to-measure-objective-transmission-curves-tp590172p590176.html

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Hi Andrew

While I can see that method would work for lenses designed to work in
air, wouldn't total internal reflection be a problem for lenses with an
NA over 1.0? The only way I can think of doing it is to use two
objectives of the same type looking at each other at a common focal
point with the right immersion medium between them. Then the overall
transmission would be half that of a single lens...

Cheers Mark

Andrew Resnick wrote:

> Search the CONFOCAL archive at
> http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal
>
> We've done similar measurements, it's not too difficult.
>
> The main trick is handling the large NA lenses.  Our setup was light
> source -> objective -> integrating sphere -> spectrometer.  After
> normalizing to the source, we obtained really good data.  It's pretty
> easy, actually.
>
> Andy
>
>
> At 08:45 AM 8/31/2007, you wrote:
>> Search the CONFOCAL archive at
>> http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal
>>
>> Dear all,
>>
>> one of the main differences of objectives is their transmission
>> efficiency at certain wavelengths. One way to compare this is the
>> trial-and-error method, however, this is not straight forward.
>>
>> My idea is to use a combination of spectrophotometer and a lamp with
>> a more or less even spectra (i.e. Xenon) on some kind of optical
>> bench. This would make the setup independent from the manufacturer.
>> Beside the distance between the light source and the detector, there
>> are obviously more things to consider: different diameter of the back
>> focal plane, different focal lenghts...
>>
>> I would like to hear about your opinion about how to measure
>> objective transmission. Have you ever done this in your lab? Did you
>> find a setup that worked for you?
>>
>> cheers,
>> Michael
>
> Andrew Resnick, Ph. D.
> Instructor
> Department of Physiology and Biophysics
> Case Western Reserve University
> 216-368-6899 (V)
> 216-368-4223 (F)