Always get sapphire window. More common than thought.
Many cell phones are sapphire and many chemical ports are. I have some
myself. Most is broken flats and I have at least one nice one.

Martin

On 6/11/2015 8:10 AM, Carl Ijames wrote:
May not be large enough but how about the quartz windows on old UV eraseable
EPROMs? Have to dig it out of the epoxy, but I'm sure lots of shops and
tinkerers have some stuck away in a junk drawer.

-----
Regards,
Carl Ijames
wrote in message ...

On 11 Jun 2015 03:11:05 GMT, "DoN. Nichols"
wrote:

On 2015-06-10, Gray_Wolf wrote:
On Fri, 01 May 2015 08:33:36 -0700, wrote:

[Snip]

I wish they were quartz because of the toughness and UV transmission.
The filter I removed was a two piece affair. At first I wondered why

[ ... ]

Perhaps a source of quarts flats would from quartz crystals used in
electronic devices. e.g. RF oscillators, computer clock control and
such. I think CCD sensors are more sensitive to IR than UV. In any
case UV doesn't transmit well through regular glass lens.

If you want optical quality windows go to newport.com They sell
parallel surface windows made from all known optical materials.
There are many other scientific optics sources on the Internet.