[time-nuts] optically excite a quartz crystal?

Poul-Henning Kamp phk at phk.freebsd.dk
Mon Apr 21 14:51:27 UTC 2014

In message <A5032606-D7D7-4231-B1BD-434670274532 at rtty.us>, Bob Camp writes:

>Early in the WWII era, quartz blanks were not commonly etched after
>begin ground / polished to frequency. This left debris on the surface
>of the blank. The net result was that the resonators failed after
>a period of time in the field, especially under damp conditions.
>The problem got so bad that it actually threatened the ability to
>communicate in 1942. A fairly high level team looked into the issue
>and etching of blanks (and a few other mods) were made a mandatory
>part of all crystals suppled to the government.

The story is slightly more interesting than that:

Blileys crystals were almost totally without these problems, but
they wouldn't tell why that might be.

In the end the government put a lot of pressure on Bliley to squeeze
out the manufacturing secret.

The secret was etching.

To keep it secret, Bliley had called it something along the lines
of "X-Grind" and not applied for a patent.

The Government forced Bliley to share the etching secret without
giving any compensation, and the Blileys were bitter about that for
the rest of their lifes.

Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.

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