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Thread: driver manual for adjusting/tuning needed

  1. #11
    Join Date
    Oct 2008


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Name:	Laser Project Building Guide and Miscellaneous Fun Stuff.pdf 
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Size:	732.9 KB 
ID:	27191

    The last page on there has a bit of information.

    Test/Dummy loads for setting the current on a laser driver.
    Measuring current without a dummy load/test load is done by placing a multi-meter’s probes between the + and – sides of the load between the current source and the load in mA or Amps. This setup works but when adjusting a trim potentiometer on the laser driver it risks damage to the laser diode if too much current is accidentally applied.

    Using a dummy load or test load allows the setup of a laser driver’s current, in mA or Amps. The basic dummy load is made up of a 1-Ohm resistor and silicon diodes; each silicon diode creates a 0.7V drop in the voltage thus creating a load. This load simulates the voltage drop that an actual laser diode would create, and allows a laser driver’s maximum current to be measured with a multi-meter. The setup of a dummy varies between different laser diodes according to the voltage needed. In the case of an IR diode needed 2.2v three INF4001 silicon diodes would create a 2.1v load on the driver. A red laser diode typically running at 3.0v four silicon diodes would be used creating a load of 2.8v. Blu-ray diodes would use six INF4001 or equivalent silicon diodes to create a load of 4.2v load. These are basic setups, check the specification sheet if available and adjust the test load to your needs, (<voltage needed>/0.7 = number of diodes) needed to simulate your load. As you can see it doesn’t always add up to the exact voltage so err on the side of caution.

    Last edited by sugeek; 09-07-2011 at 10:21. Reason: added in what I wrote in the pdf
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    Laser (the acronym derived from Light Amplification by Stimulated Emissions of Radiation) is a spectacular manifestation of this process. It is a source which emits a kind of light of unrivaled purity and intensity not found in any of the previously known sources of radiation. - Lasers & Non-Linear Optics, B.B. Laud.

  2. #12
    Join Date
    Feb 2010
    Melbourne, Australia


    Thanks Sugeek! That's the clearest explanation I've read. I had a search around on PL yesterday, but there was nothing quite as succinct as that.

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