Page 2 of 2 FirstFirst 12
Results 11 to 15 of 15

Thread: "unknown" YVO4 crystal

  1. #11
    Join Date
    May 2011
    Posts
    4

    Default

    Hello,

    thank you for your interest. My crystal is exactly the one that was posted here:
    http://cgi.ebay.com/ND-YVO4-Vanadate...-/150593785076

    Well not 100% the same because it has not the thermistor mounted but it comes from the same seller and is otherwise the same.

    Its dimensions are 5x5x8mm the longest dimension along optical axis. The dopant percentage is 1.5%

    My intention is to try to bounce off distant objects like clouds or mountains and see if it is at all possible and if so have an estimate of the distance (high precision is not required). In fact my real interest is in communications but I don't expect to have much correspondents at this wavelength.

    Pulse operation is attractive for two reasons:
    - better time of flight precision. In the paper I read the sawtooth at relatively low frequency (period in the millisecond area) produces a pulse in the microsecond area.
    - more power is possible while maintaining eye safety at a distance. I also want to use beam expansion.

    I hope these details make things more clear.

    Best regards,
    Edouard.

  2. #12
    mixedgas's Avatar
    mixedgas is offline Creaky Old Award Winning Bastard Technologist
    Infinitus Excellentia Ion Laser Dominatus
    Join Date
    May 2007
    Location
    A lab with some dripping water on the floor.
    Posts
    9,186

    Default

    One, you can do that with just a diode:

    http://www.allweatherinc.com/meteoro...oudheight.html

    Only reason I know about the above is my friend is a private pilot and we had a little debate about his data sources on a night with unfriendly weather. I was on board at the time and I did not like depending on the FAA ASOS Weather Station which uses a similar single point diode laser based measurement.

    Two, a intracavity AOM is only going to set you back 40-50 euros if you are a careful shopper and would give you a much better control of the Q-switched pulse.

    Also, read up on the modulated CW methods of ranging such as

    http://en.wikipedia.org/wiki/Tellurometer

    http://www.fig.net/pub/fig2008/paper...right_2833.pdf


    I'll find you data more relevent to your crystal in a few days.

    I do not know if these can be exported, but read:

    http://www.eodevices.com/main_erc_4_frameset.htm

    I was looking at a pulsed CO2 based rangefinder for a potential client a while back, the above was a good low cost timing board for prototyping.

    Steve

  3. #13
    Join Date
    May 2011
    Posts
    4

    Default

    Quote Originally Posted by mixedgas View Post
    One, you can do that with just a diode:
    Two, a intracavity AOM is only going to set you back 40-50 euros if you are a careful shopper and would give you a much better control of the Q-switched pulse.

    Steve
    I have seen this AOM on eBay that would cover 1064nm:
    http://cgi.ebay.fr/IntraAction-AOM-4...-/150604259428

    What do you think?

    For direct diode operation I am also thinking of it but 1064nm is quite desirable for low atmospheric losses. Power diodes on 1064nm are very expensive. I also have 1550nm power laser diodes that were used for range-finding initially. 1550nm is also a good atmospheric window and I will possibly try it too but the advantage of 1064nm is that it is still visible for normal CCD cameras which can be useful for building and tuning.

    Best regards,
    Edouard.
    Last edited by f4exb; 05-17-2011 at 05:32. Reason: missed one point

  4. #14
    Join Date
    May 2011
    Posts
    4

    Default

    Hi,

    examining once again the crystal mount made me thing it could come from a Spectra-Physics ZLM laser. This is a several watt 1064 nm laser that uses a "Z fold" cavity and is normally pumped by two diodes.

    See Sam's Laser FAQ here:
    http://members.misty.com/don/laserscl.htm#sclspzlmh

    An annotated picture of the cavity can be found here:
    http://members.misty.com/don/zlmtop1.jpg

    The two holes on the sides are needed for the Z-fold to work and are characteristic of this type of mount. The light passes straight through the holes (top and bottom bars of the "Z") and oblique through the crystal (the middle bar of the "Z"). The Z-fold mirrors should be HR at 1064 and AR at 808nm to let the pump light go through but constrain the 1064nm within the "Z". The HR mirror at the end of the top branch of the "Z" could be any mirror I suppose as long as it has good reflectivity at 1064nm (it can reflect any other wavelength too). Of course the OC mirror is located at the end of the bottom branch of the "Z".

    So this is a little bit more complex than the usual linear cavity. Only one "single wimpy diode" :-) can be used according to the FAQ though only with reduced power. In this case the Z-fold mirror 2 can be any good mirror I suppose since there's no need to have different faces for 808 and 1064nm. So I suppose one should be able to get away with one AR 808 / HR 1064nm mirror, one OC mirror and a couple of "normal" mirrors.

    What do you think?

    Best regards,
    Edouard.

  5. #15
    Join Date
    Oct 2010
    Location
    Athens, Greece
    Posts
    1,931

    Default

    Quote Originally Posted by f4exb View Post
    What do you think?
    I think i should thank you very much for your research and info!


    It may take a considerable ammount of time before i get working on this, as it is currently project number 17 in my priority list of things to do... i've got to finish off my "small" rgb, then get working on the "big" rgb and many smaller things in between

    that's why i half-offered this item if anybody has a good use for it. if it doesn't find better use at a new home, i will get to it eventually

    single end pumping is the logical first step for me, i'm not after 10w of 1064. In fact, i am not after any ammount of 1064 that does not terminate on a KTP / LBO etc
    "its called character briggs..."

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •