[time-nuts] optically excite a quartz crystal?

Bob Camp lists at rtty.us
Mon Apr 21 11:24:43 EDT 2014


Hi

As with all “good stories” there are many versions told by many people. I’ve heard far to many mutually contradictory versions to have any real idea what’s true. You are correct that etching was a known process in the 1930’s and that it had been used by various people at various times. Since it added time (and complexity) to the process, it got dropped by most people to speed up production …

Bob

On Apr 21, 2014, at 10:51 AM, Poul-Henning Kamp <phk at phk.freebsd.dk> wrote:

> 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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