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Yes Jim!

That's a good method and if the hemispherical lens is well AR coated 
then it should let the light out accurately. We used a drop of water on 
top of a water lens a while back but that won't work for a horizontal 
measuring system. Not sure about the detector angular dependence tho'. 
It might be interesting  to compare the 'two lens method'  I suggested 
(which will have no detector problems) with your integrating sphere 
method...

Anyone here fancy getting a paper in microsc. techniques or optics letters?

Cheers Mark

though. the James Pawley wrote:
> 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!!.
>
>