I have a really neat xtal - lots of RF ones, but a 2.0000 KHz.
It is a tight tolerance Audio grade.

Kinda neat. I haven't taken it apart - I want the 2k as is -
but wonder the design - long I suppose. But more than one xtal ?
Is it filtered or just finely ground to audio tone generator.
Saws are used to fine tune and trim - in RF.

Martin

On 6/10/2015 10:11 PM, 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.

The problem with the quartz used in frequency-determining
crystals is that they are ground to thickness, and thus have a frosted
look, not a nice flat surface to allow it to act as a window/filter for
images. The older ones are mounted between two metal plates which make
contact only at the corners, with a spring applying pressure to the
upper plate.

Later ones have metalized surfaces on each side, with a
spring-formed wire soldered to the center of each. There, even if the
surface were flat enough for optical image transmission, you would have
to dissolve the metal coating with an acid which would attack the metal
without attacking the quartz.

And -- the largest that I have ever seen was about 1/2" square,
which is not likely to be large enough for the sensor in question.
(Well ... I've never opened the two inch long can for a 1 KHz crystal
which I have, but it still would not be wide enough, even if it were
long enough.

Good Luck,
DoN.