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Dear Lauren

My intuition tells me that that the working distance loss due to a 
thicker coverslip cannot fall to zero with higher NA lenses.... (else I 
would be able to use a coverslip thicker than the WD!!!).

Cheers Mark

Peterson, Lauren M. wrote:
> Search the CONFOCAL archive at
> http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal
>
> Richard - I believe that your 'HOWEVER' is a bit more complicated than you suggest and also not quite as bad as you say in that you do not loose as much working distance.  I did a simple ray tracing based upon Snell's Law for the rays going through the cover slip to find that for large NA the "lost" working distance in your example is not 20um but 20/n = 20/1.523 = 13.1um.  This is the case for NA < 0.3 and assumes that objective to coverslip is air.  For larger NA, WD lost is even less than 20/n and goes to zero for the largest NA = 1 in air.
>   
>