[time-nuts] optically excite a quartz crystal?

Max Robinson max at maxsmusicplace.com
Sun Apr 20 21:17:50 EDT 2014


Ya, I remember those FT243s.  I used some when I was a novice KN4ODS.

Regards.

Max.  K 4 O DS.

Email: max at maxsmusicplace.com

Transistor site http://www.funwithtransistors.net
Vacuum tube site: http://www.funwithtubes.net
Woodworking site 
http://www.angelfire.com/electronic/funwithtubes/Woodworking/wwindex.html
Music site: http://www.maxsmusicplace.com

To subscribe to the fun with transistors group send an email to.
funwithtransistors-subscribe at yahoogroups.com

To subscribe to the fun with tubes group send an email to,
funwithtubes-subscribe at yahoogroups.com

To subscribe to the fun with wood group send a blank email to
funwithwood-subscribe at yahoogroups.com

----- Original Message ----- 
From: "Bob Camp" <lists at rtty.us>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Sent: Sunday, April 20, 2014 8:05 PM
Subject: Re: [time-nuts] optically excite a quartz crystal?


> Hi
>
> The WWII era FT-243 is one example of a crystal that has the active 
> portion of the electrodes separated from the resonator by an air gap. 
> There are lots of similar holders from that era that do pretty much the 
> same thing. Non-contacting electrodes are not very new.
>
> Bob
>
> On Apr 20, 2014, at 8:47 PM, Max Robinson <max at maxsmusicplace.com> wrote:
>
>> It seems that it would be relatively easy to apply an electric field to a 
>> quartz plate without actually making physical contact.  However, Star 
>> Trek's force field hasn't been invented yet so there must be some way to 
>> support the plate.  If you could arrange to support it on the nodes you 
>> could excite it with a non contact electric field and then read it out 
>> with a laser.
>>
>> Regards.
>>
>> Max.  K 4 O DS.
>>
>> Email: max at maxsmusicplace.com
>>
>> Transistor site http://www.funwithtransistors.net
>> Vacuum tube site: http://www.funwithtubes.net
>> Woodworking site 
>> http://www.angelfire.com/electronic/funwithtubes/Woodworking/wwindex.html
>> Music site: http://www.maxsmusicplace.com
>>
>> To subscribe to the fun with transistors group send an email to.
>> funwithtransistors-subscribe at yahoogroups.com
>>
>> To subscribe to the fun with tubes group send an email to,
>> funwithtubes-subscribe at yahoogroups.com
>>
>> To subscribe to the fun with wood group send a blank email to
>> funwithwood-subscribe at yahoogroups.com
>>
>> ----- Original Message ----- From: "Attila Kinali" <attila at kinali.ch>
>> To: "Discussion of precise time and frequency measurement" 
>> <time-nuts at febo.com>
>> Sent: Sunday, April 20, 2014 2:50 PM
>> Subject: Re: [time-nuts] optically excite a quartz crystal?
>>
>>
>>> On Sun, 20 Apr 2014 10:35:08 -0700
>>> <cdelect at juno.com> wrote:
>>>
>>>> After reading about how the BVA oscillators avoid the problems of "on
>>>> crystal" electrodes I was wondering if anyone has tried to optically
>>>> excite a quartz crystal in an oscillator?
>>>>
>>>> (Use a modulated laser to drive the bare crystal, and a photodetector
>>>> setup to detect and provide feedback?)
>>>>
>>>> Seems like it might work. Any comments?
>>>
>>> I am not really sure about that.
>>>
>>> (Disclaimer: my knowledge about solid state physics and piezo-electric
>>> devices is at best rudimentary, so please correct me if i'm wrong)
>>>
>>> The oscillations of the quartz crystal are deformations of the
>>> crystal lattice. This deformation is induced by applying an electrical
>>> field and coupled into the lattice over the piezo-electric effect.
>>>
>>> The wavelength of the electromagnetic field is usually much much larger
>>> than the dimensions of the crystal involved. As such, the field can be
>>> seen as constant trough the crystal. I.e. the field induced strain on
>>> the lattice is constant trough the whole length.
>>>
>>> On the other hand, the wavelength of lasers is in the order of a couple
>>> thousand times the lattice constant (approx 0.5nm). I.e. the field of
>>> a laser within a quartz crystal wouldn't be constant if one would be
>>> to use a crystal in the sweet spot region between 1MHz and 10MHz.
>>> Using two lasers with a ~10MHz frequency difference and using two
>>> photon absorbtion will probably yield to a very small energy coupling
>>> to induce any measurable oscillation, if it is possible at all
>>> (i don't know of any effect that would translate a two photon absorption
>>> into lattice oscillations).
>>>
>>> Thus, i don't think it would be possible to induce oscillations in a 
>>> quartz
>>> crystal using a laser based system.
>>>
>>>
>>> On the other hand, there are currently experiments running to use lasers
>>> to generate RF frequency refernces coupled to the interogation of atomic
>>> clocks (see e.g. [1]) and the results are comparable to ultra low noise
>>> crystal oscillators.
>>>
>>>
>>> Attila Kinali
>>>
>>>
>>> [1] State-of-the-Art RF Signal Generation From Optical Frequency 
>>> Division.
>>> by Hati, Nelson, Barnes, Lirette, et. al., 2013
>>>
>>> -- 
>>> I pity people who can't find laughter or at least some bit of amusement 
>>> in
>>> the little doings of the day. I believe I could find something 
>>> ridiculous
>>> even in the saddest moment, if necessary. It has nothing to do with 
>>> being
>>> superficial. It's a matter of joy in life.
>>> -- Sophie Scholl
>>> _______________________________________________
>>> time-nuts mailing list -- time-nuts at febo.com
>>> To unsubscribe, go to 
>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>> and follow the instructions there.
>>
>>
>> ---
>> This email is free from viruses and malware because avast! Antivirus 
>> protection is active.
>> http://www.avast.com
>>
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com
>> To unsubscribe, go to 
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to 
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there. 


---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com



More information about the time-nuts mailing list