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Thread: Happy 60th Birthday Laser Light!

  1. #1
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    Default Happy 60th Birthday Laser Light!

    Here's a pic of the workbench used by Ted Maiman and Irnee D'Haenans that day, showing the laser head pointing into a Bausch & Lomb spectrometer.

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    Sorry for the double pic. Something buggy prevents me from managing attachments.

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    I was just looking through Maiman's book about his laser. Of course he mentions Schawlow's misstatements about pink ruby at the '59 Shawanga Lodge Conference, and says those statements "came back to haunt him". "Members of the scientific community familiar with the facts circulated a joke: "<em>Schawlow is buying up all the copies of the Shawanga Lodge Conference Proceedings and burning them."

    Here's one he missed. Got it from Tony Siegman shortly before he passed. Notice on the first page of comments after Schawlow's talk, Gordon Gould mentions pulsed optical pumping.
    Attached Thumbnails Attached Thumbnails Shawanga Book.jpg  


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    Quote Originally Posted by Eidetic View Post
    Something buggy prevents me from managing attachments.
    I've been having similar trouble for some time now. I think it's related to the intermittent bug where you can't view attached pictures on some threads unless you open them in a new window and re-enter your login credentials. Last time I mentioned it to Spec he had no idea what was causing it.

    Quote Originally Posted by Eidetic View Post
    Of course he mentions Schawlow's misstatements about pink ruby at the '59 Shawanga Lodge Conference
    I'm not familiar with those statements, and a quick google search came up dry... Care to elaborate?

    Adam

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    Schawlow dismissed pink ruby as a potential laser medium saying "The two strongest lines (6919A and 6934A) go to the ground state, so that they will always have more atoms in their lower state and are not suitable, for Maser action." Maiman was in the audience, and relaized Schawlow was talking about cryogenically cooled ruby, not room temperature ruby, and was wrong.

    The issue of pulsed optical pumping is interesting though. Maiman claims to have originated this idea after concluding that continuous pump lamps would not be bright enough. He said that "once (he) put pumping requirements in terms of brightness temperature, (he) began to think in another way." Reading about photographic strobe lamps, he found that they were capable of reaching the color temperature required for a pumping source. He called this his "aha!" moment. Reading the comments in the Shawanga proceedings however, shows Gordon Gould proposing pulsed optical pumping. I suppose nobody cares, and both are dead.
    Last edited by Eidetic; 05-17-2020 at 13:06.

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    Thanks for the clarification. In fairness, given that ruby is a 3 level medium I can see why Schawlow thought that it was unsuitable. 4 level mediums perform far better. But you *can* get a 3 level medium to lase - albeit inefficiently.

    Regarding cryogenically cooled ruby though: I thought there was a quasi-CW ruby that was cryogenically cooled? (Seem to remember something about that in Carroll's "Story of the Laser"...)

    Adam

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    There is CW ruby. Cooled Rod pumped by 514 Argon is known. A while back
    [COLOR=rgba(0, 0, 0, 0.84)] Klastech [/COLOR]
    had a CW DPSS 694, and its difficult to tell if they had a 450 diode directly pumping the upper state or a 532 nm Green DPSS pumping the upper state, no one is talking and the unit is off the market.

    Steve


    Link one: https://www.researchgate.net/publication/260634347_cw_ruby_laser_pumped_by_a_5145_A_argon_l aser

    Link two: https://ui.adsabs.harvard.edu/abs/1977IJQE...13..808B/abstract

    There are others.

    Steve


    Last edited by mixedgas; 05-19-2020 at 15:02.
    Qui habet Christos, habet Vitam!
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    When I still could have...

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    Thanks for the links Steve! I thought I remembered something about a CW ruby that was cryogenically cooled. Didn't realize it was pumped by an argon laser though. I don't see any reason why it couldn't be pumped by a continuous flashlamp though, apart from the absorption inefficiency that is.

    I have to admit that even though I realize how impractical and inefficient a ruby laser is, there's still a part of me that wants to buy or build one just for the hell of it.

    Adam

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