http://confocal-microscopy-list.275.s1.nabble.com/How-to-measure-objective-transmission-curves-tp590172p590181.html
describe. There are more high NA rays than low NA rays (due to the area
of an annulus increasing with it's radius : pi(2r dr). As I see it, one
field stops (or even phase rings!). The measurement of throughput is
certainly not going to be easy. I don't see how this is related to the
> Search the CONFOCAL archive at
>
http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal>
> Mark,
>
> That's a good question. We attached a coverslip with a small drop of
> oil to the objective as a way to deal with immersion objectives. I
> don't know what it means that the "sample" is in air; if some light is
> then totally internally reflected back into the coverslip, which could
> be a spectral issue due to dispersion.
>
> Using two matched objectives is probably a better method, but I
> imagine considerably more difficult due to alignment constraints and
> obtaining matched objectives. The objectives we had obeyed the 'sine
> condition', which I believe means that there are fewer high-NA rays
> than low NA rays- this would help mitigate our experimental error as
> well.
>
>
> At 04:19 PM 9/2/2007, you wrote:
>> Search the CONFOCAL archive at
>>
http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal>>
>> 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)
>>
>> Andrew Resnick, Ph. D.
>> Instructor
>> Department of Physiology and Biophysics
>> Case Western Reserve University
>> 216-368-6899 (V)
>> 216-368-4223 (F)