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

Just had a look in the ThermoNicolet (http://www.thermonicolet.com)
catalogue for FT-IR accessories, and they supply windows of various
minerals in a range of sizes - the closest to a coverslip would be the 20
mm diameter x 2 mm thick window.  This company says "other materials and
dimensions are available upon request"
No commercial interest........

>Search the CONFOCAL archive at
>http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal  Tom.
> I am an import/export engineer and source, worldwide, hard to locate
>technological products or components.
> <http://www.price-solutions.com/>www.price-solutions.com
>
> The request was from a research university for use with an Olympus system
>for molecular microscopy.
> Previously the coverslips with a refractive index of 1.78 were supplied
>by Olympus.
> However my understanding is that Olympus can no longer supply them.
> The university asked me to find an alternative supplier.
> To date without success.
>
> Thank you Tom for your curiosity.
>
> Philip
>
>