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Thread: Modulator Choices

  1. #1
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    Default Modulator Choices

    When using lasers that are not directly modulated such as an argon or as in my case a very rapidly pulsed (25KHz) dye laser, what are the relative merits of an AOM and a galvanometer based steering mirror? Are there any methods available that allow dimming as opposed to on vs. off? I'm thinking about cost, speed, aperture, power handling, and easy integration with typical 0-5V drive signals.
    Last edited by planters; 09-19-2011 at 15:01. Reason: spelling

  2. #2
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    mixedgas is offline Creaky Old Award Winning Bastard Technologist
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    AOM and GALVO both do what you want. Galvo does it cheaply, but slower, and it can be tricky to reduce unwanted "Blanking tails" without using retroreflective blanking or lenses. AO has a downside that on a good day with a tailwind you can get perhaps 92% transmission, typically the minimum will be 80%, however. It also depends if your AO can handle random polarization or not, and many cannot.

    AOM can be remarkably linear and is blazing fast, and if you want true 30K point by point blanking, your going for AO. Your not going to do fine "RASTER" images with galvo blanking, at least not very well.

    On the other hand I used galvo based RGB for about two years, using a microflag inserted into a focal spot between two lenses, and had many favorable comments from professional laserists, all of whom said it would "NEVER" look good. The trick is in how you tune the blanking galvo, and I'd be glad to disclose that off list. The problem with the small adsorptive flag is that you can cook the daylights out of the galvo shaft and bearings, depending on your laser's power.

    Steve

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    I was looking at your post again and now that I am setting up a Q-switched YAG and will, in the next few months, graduate to the dye module I will need to get into this modulator in a real way. The flag at the interim focus is intriguing if the set up isn't just too dicey, as there will not be any "tails" with this technique. To reduce the heating issue (10-20 W) what do you think about fabricating the flag at a 45 degree angle, leaving it reflective and then dump down to the optical table?

  4. #4
    mixedgas's Avatar
    mixedgas is offline Creaky Old Award Winning Bastard Technologist
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    BTDTGTTS

    45' mirror is oK,there are other ways.

    I'll tell you how to adjust the scanner amp off list.

    Steve

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