Re: How to measure objective transmission curves?

Posted by James Pawley on
URL: http://confocal-microscopy-list.275.s1.nabble.com/How-to-measure-objective-transmission-curves-tp590172p590216.html

Search the CONFOCAL archive at
http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal

Hi all,

If it doesn't sound too commercial, I would like to note that a lot
of objective transmission curves are published in the 3rd Edition. In
fact I take some pride in the fact that the earlier editions of the
Handbook contain some of the first published transmission data on
commercial objectives.

One trick to get "all the light" out of an high NA is to oil-couple
it to the flat side of a very small hemispherical lens. Even a small
glass bead, with half of its thickness sticking out of the oil will
do.

But you have to hold your light sensor really close to it, and if you
aren't careful, because the light diverging from the focus in the
bead will leave it at such a large angle to the horizontal that a lot
of it may be reflected from the glass covering your sensor (or miss
it all together). An optometrical integrating sphere is better.

I just measure transmission of the system (mostly losses in the fiber
and filters) with the 10x lens and hope that the immersion lenses
"are what they are".  However, this won't show up a smear on the tube
lens that only obscures high-NA rays. I use the focusing ability of
the Bertrand lens (phase lens) to look for this by focusing up and
down through the optical column.  Amazing how much dust etc. you can
see this way!!.

Cheers,

Jim P.

>Search the CONFOCAL archive at
>http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal
>
>Jens,
>
>I could not find the data- I must have left it behind.  I don;t
>recall anything odd; the transmission curves were uniformly high in
>the visible and dropped off to about 50%, IIRC, at 1064 nm (the
>laser tweezer wavelength).
>
>Andy
>
>At 10:04 AM 8/31/2007, you wrote:
>>Search the CONFOCAL archive at
>>http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal
>>
>>Dear Michael & Andy,
>>
>>For Olympus lenses you can look it up on the web...the info for other
>>manufacturers lenses would be interesting though; do you plan to publish
>>the numbers? Andy, would you mind to disclose yours?
>>
>>regards, jens
>>
>>---
>>Dr. Jens Rietdorf
>>Head Microscopy
>>Novartis Research Foundation
>>Friedrich-Miescher-Institute, wro1066.2.32
>>Maulbeerstr.66, CH-4058 Basel, Switzerland
>>phone [phone] mobil [phone]
>>Email:rietdorf(at)fmi.ch
>>
>>-----Original Message-----
>>From: Confocal Microscopy List [mailto:[hidden email]] On
>>Behalf Of Andrew Resnick
>>Sent: Freitag, 31. August 2007 17:00
>>To: [hidden email]
>>Subject: Re: How to measure objective transmission curves?
>>
>>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)

--
               ****************************************
Prof. James B. Pawley,                 Ph.  608-263-3147
Room 223, Zoology Research Building,                         FAX  [phone]
250 N. Mills St., Madison, WI, 53706  [hidden email]
"A scientist is not one who can answer questions but one who can
question answers."  Theodore Schick Jr., Skeptical Enquirer, 21-2:39