Page 1 of 2 12 LastLast
Results 1 to 10 of 16

Thread: The notebook of Anna Magdelenna Bach.

  1. #1
    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
    9,439

    Default The notebook of Anna Magdelenna Bach.

    Once upon a time when Bach was younger, he fell in love with a good looking lady that had no training in music, but he thought she had the nack to be a performer of music.
    He wrote one of his more famous and useful compilation of songs for her in a notebook, so she could learn piano. Its also more fun then his usual stuff. To this day it is a popular composition and played often. BTW, he married her. Anna Magdalena did learn to play the piano quite well, we are told.

    I too have a notebook. Only I didn't do this one. It is a series of designs done a few years ago for DPSS green by a PHD engineer who has left the country. Nothing in it is patented, nor patentable. Even comes with some part numbers. Whom would like to host and scan about 50 8.5 x 11 pages of data? Its almost as good as Bach's notebook. It comes with performance graphs and test results too. everything from 50 mW to 5 watts, CW and Qswitched, diode pumped.

    I ask that you keep it up for a year, and scan everything I send you. I'll leave out the parts that could get a host site in legal troube to the best of my ability. Expect some big time download traffic.

    Steve

  2. #2
    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
    9,439

    Default More ANNA MAGDALENA

    SEE ATTACHED.

    This was in 98, diodes have gotten a lot better.

    perfomance curve coming,
    Attached Thumbnails Attached Thumbnails vcav750.bmp  

    Last edited by mixedgas; 11-19-2008 at 11:34.

  3. #3
    Join Date
    May 2007
    Location
    Minnesota
    Posts
    160

    Default Notebook

    Hey Steve,

    "Whom would like to host and scan about 50 8.5 x 11 pages of data?"

    If no one else wants to, I am more than willing Actually frothing at the mouth...

    We have a new copier/scanner at work that does everything. I have some server space and will be happy to upload for everyone to see.

    Anyway, let me know.

    -George

  4. #4
    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
    9,439

    Default

    hologeek wrote:

    If no one else wants to, I am more than willing Actually frothing at the mouth...

    PM sent. Any others?

    Attached is the performance curve

    optics spacing will come when hologeek et al scans it

    Steve
    Attached Thumbnails Attached Thumbnails vcav1pwr.bmp  

    Last edited by mixedgas; 11-19-2008 at 13:16.

  5. #5
    Join Date
    Jun 2008
    Location
    Austin Texas since 1976
    Posts
    250

    Default Yes steve I can run ftp host program and I have enough bandwirth for modest usage

    I think I can crete a IP tunnel for remote access to upload larger files, I was thinking of mirroring the ilda swap stuff.
    Quote Originally Posted by mixedgas View Post
    hologeek wrote:

    If no one else wants to, I am more than willing Actually frothing at the mouth...

    PM sent. Any others?

    Attached is the performance curve

    optics spacing will come when hologeek et al scans it

    Steve
    clicking on my avatar will show the tricolor photocoagulator resonator cavity from a Lumenis Varia eye surgery medical laser, which i am attempting to refit. It originally was designed to produce 50-1500mw of 532 / 50-600mw of 659nm / 50-600mw of 561nm (Yellow)
    Clicking on my Avatar will show a picture of the inside of this cavity with a 1cm bar diode in the first of 3 OEM postions & KTP holder.
    Caviar Dreams on pennies, well lots of pennies.

  6. #6
    Join Date
    Nov 2007
    Location
    Coming to a theatre near you!
    Posts
    521

    Default

    any chance you could provide a copy of that first bitmap with explanations of each part? I know it's dpss 101, but some of us are noobs when it comes to the inside-the-case stuff. I understand most of it,but the abbreviations are a little confusing,and are there two diodes in that setup?
    "TO DO IS TO BE" - Nietzsche
    "TO BE IS TO DO" - Kant
    "DO BE DO BE DO" - Sinatra

  7. #7
    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
    9,439

    Default

    HERE WE GO:
    worlds shortest DPSS theory page:

    You've got three active elements, the pump diode (a laser in its own right) a lasing crystal, in this case Neodymium Doped Yttrium Orthvanadate(Nd:YVO4) Crystal, the ND lases,the YVo4 is structural and called a host. . YVo4 is clear like glass, the ND makes it purple. No Nd, no lasing. YVo4 is good at conducting out heat, which is essential. Potassium titanyl phosphate (KTiOPO4) is the doubling crystal. It takes the 1064 lasing light and for all practical purposes adds two photons of 1064 to each other to double the energy to green light. How it does this is best just accepted as magic at first. Its a energy hog of a process, and requires huge energy fields to work, hence the process is named non-linear optics. It doesn't occur much in nature, and it basically has only happened in large amounts since the invention of the laser and the arc lamp.

    On the drawing:

    One pump diode emitting 5 watts from a 1 micrometer thick chip, that emits a 20 degree by 40 degree beam.

    The cylindrical lens CY-L does a 4:1 compression on that 40 degree wide angle but nothing on the 20 degree part of the pump beam. This makes it closer to a round spot in the laser crystal, making it more likely to get you a nice round beam, and use the maximum amount of pump light as well. The spherical lens SP-L focuses it into the ND:YVO4, which is doped with 6 tenths of a per cent atomic weight ND. The back side of the vandate is coated (high reflect) to reflect the lasing wavelength of 1064 nm. The same coating is antireflection (AR) for the 808 nm pump light. The side of the coating on the vandate inside the cavity is AR for both 1064 and 532. In theory all the 808 is adsorbed. In reality its about 79%, the rest becomes heat or leaks out some place. The rear face of the vandate forms one of the cavity mirrors and is polished to be flat, hence the radius is marked infinity,


    The Brewster angle plate made of fused silica is angled at 55.3 degrees. At 55.3 degrees it prefers to transmit one polarization , and is very lossy for the other polarization. This forces the vandate to have gain at 500:1 or better for the one polarization and almost no gain at the other. This is essential for peak power conversion in the doubling crystal.

    The radius of the two mirrors M1 and M2 is set up to do two things, one, make a focal point inside the vandate (a beam waist) That matches the focal point caused by the pump optics. Imagine two cones , one pump light, one dark adsorbing one where the lasing is occuring. So the mirrors are set up to cause the pump focal point and the laser beam waist to overlap in space. This way you have maximum power density, and thus maximum gain, and a small tight beam. Since the doubling process is a really non-linear process, it needs maximum
    energy to occur, so the M1, M2 combination also sets up the maximum amount possible of energy at a second focal point inside the KTP Doubling crystal. Because there are 3 mirrors, there are two waists in the cavity. With two mirrors like a hene laser you only get one waist. Hence the fold at the output coupler back to M2. Thats why its called a "V" or VEE cavity.

    As green light is generated in both directions out of the KTP crystal, the one mirror reflects both 1064 nm and 532 light. The other mirror is coated to allow 532 out, but reflect 1064 back down the cavity so lasing occurs. SO HT= a high transmission coating.

    The littrow prism is a low loss prism (one face at brewsters angle, see above) that seperates any leaking 1064 and 808 coming out of the cavity, so you have a clean, green only beam.

    The last spherical lens compensates for the fact that the green light is diverging highly from that beam waist (focal point) inside the KTP. It collimates the green light and makes it as parallel as possible.

    Frequency doubling has some weird properties with respect to the angular orientation of the atomic structure of the crystal, so the crystal is cut to two specific angles, Theta and Phi, with respect to its optical axis (limaginary line between the pointy ends of the natural crystal) and there is a note there to rotate the "C" axis of the KTP at 45' to the
    polarization of the light inside the cavity. Light, like everything else electromagnetic, has its magnetic field at right angles to its electric field, and that matters in the doubling process. By rotating the crystal , the crystal starts to act like a quarter waveplate, and it causes the electric field in the crystal to spin a bit, otherwise it creates periodic spots in the crystal where the field is way too high. When the field is way to high the crystal actually starts to adsorb the green and it doesn't work so well. The green will actually flicker on and off very fast if you don't spin the field some how. The spinning field makes sure it rarely passes through the same spots on a atomic level and evens things out. The crystal is coated antireflect on both ends for 1064 and 532.


    Thats the basics of the notations on the paper. There are a few more. The diode is mounted on a heat sink and a Thermo-electric cooler on the drawing. A TEC is a device to pump heat out of the pump diode to match its wavelength to the peak adsorbtion of the laser crystal. The diode shifts wavelength about .1 nanometer per degree c, so you want to keep it at its design temperature, as vandate has a narrow adsorption window a few nanometers wide. Thats why cheap pointers change power like crazy as they warm up, since they have no temperature control, the diode shifts wavelengh right out of the adsorption peak.

    The KTP crystal is heated to peak and tune its effects and to cause healing of defects in the KTP as it gets "burnt" by the high power laser light inside it. The heat sort of lets it "melt" locally where there are adsorbing defects and the atoms slowly move back to where they should be. It is not really hot enough to be melting, but the heat does free up the shifted atoms. KTP actually melts at 1172 c, but crystals are cut for room temperature for cheap laser and about 85 C for good ones with KTP ovens.

    This is a END PUMPED laser, as opposed to a side pumped laser.

    BTW, the mirror radius is marked instead of the focal length on the mirrors, to get the focal length, divide the radius by two. So R = 20 mm means a 10 mm focal length.

    Any questions, please ask.

    Steve Roberts
    Last edited by mixedgas; 11-19-2008 at 20:34.

  8. #8
    Join Date
    Jun 2008
    Location
    Austin Texas since 1976
    Posts
    250

    Default Dear Steve I can Scan them as well as create a file server or upload to ilda swap

    When ever you say go I will be ready! Thanks From Dave
    clicking on my avatar will show the tricolor photocoagulator resonator cavity from a Lumenis Varia eye surgery medical laser, which i am attempting to refit. It originally was designed to produce 50-1500mw of 532 / 50-600mw of 659nm / 50-600mw of 561nm (Yellow)
    Clicking on my Avatar will show a picture of the inside of this cavity with a 1cm bar diode in the first of 3 OEM postions & KTP holder.
    Caviar Dreams on pennies, well lots of pennies.

  9. #9
    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
    9,439

    Default

    [QUOTE=Mr.Coffee;69927]any chance you could provide a copy of that first bitmap with explanations of each part? I know it's dpss 101,

    SEE ATTACHED BMP

    Steve
    Attached Thumbnails Attached Thumbnails lightpaths.bmp  


  10. #10
    Join Date
    Jan 2008
    Location
    Stockholm, Sweden
    Posts
    799

    Default

    I can host a http mirror of the scans here at home. I have a 10Mbit connection here, but if that doesn't cope with it I'll just upload it to my university's web server. That one usually does 10MB/s per connection. I think I still have unlimited space as I used to be webmaster.

    It would be nice to have a PDF of this, OCR'ed if anyone have time to proofread it.

Posting Permissions

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