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  1. #1
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    Default Does laser diode ever decay ?

    Can the output power of laser diode in a LIDAR gun decay over time (long time)?
    or can we expect a "all or none" output power output from a laser diode?

    the LIDAR gun used by the LEO seemed to last very long time.

    what is the approximate life span of a laser diode? (so that we can expect the life span of a laser diode jammer?)

  2. #2
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    Osram advertises their Laser Diodes to last for an average of 40,000 hours. But it also depends on how the jammer is driving the diode and dissipating heat. Here's what they say:

    Introducing Indium in the active laser region almost completely eliminates early spontaneous laser diode failure by pinning the crystal defects responsible for dark line defects. As a result, aging today is typically a slow continuous process of degradation. Average lifetime is over 40000 hours. Such high reliability reduces the downtime and maintenance costs of the end product. The lifetime of a laser diode depends mainly on the ambient temperature and optical output power. A temperature decrease of 20 K leads approximately to a four times higher life time. Otherwise, reducing the optical power to half of the maximum power, the lifetime is increased by a factor of three.

  3. #3
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    Depends on how well the designer followed the maximum operating constraints. In high power, short pulse width, very slow rep rate applications of pretty much any semiconductor the constraints much be closely followed. In a lot of cases even the manufacturer doesn't know for sure where the limit is. Heat is a factor but the heat you can measure at the outside of the device may have little to do with the heat internally (instantaneous junction temperatures) when operated in the above manner.

    There are methods to measure this but I have no idea if the diode manufacturers have done any of this work. I would doubt it since I would guess the market for these type of laser diodes in not all that big.

    You might want to ask any laser jammer manufacturer what his design test method was. For instance did he run the jammer by detecting a laser gun and then jamming with a reasonable jam length and then keep repeating this process with a reasonable interval between test cycles.

    Given the relatively poor reliability of some jammers that has been reported on this site I doubt many if any go through this process. The current method of operation seems to be "oh it broke? I'll send you a new one or at least some new components". To my way of thinking this is a poor method of operation but maybe that is the only method this low volume business can support.

  4. #4
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    Quote Originally Posted by jimbonzzz
    Osram advertises their Laser Diodes to last for an average of 40,000 hours. But it also depends on how the jammer is driving the diode and dissipating heat. Here's what they say:

    Introducing Indium in the active laser region almost completely eliminates early spontaneous laser diode failure by pinning the crystal defects responsible for dark line defects. As a result, aging today is typically a slow continuous process of degradation. Average lifetime is over 40000 hours. Such high reliability reduces the downtime and maintenance costs of the end product. The lifetime of a laser diode depends mainly on the ambient temperature and optical output power. A temperature decrease of 20 K leads approximately to a four times higher life time. Otherwise, reducing the optical power to half of the maximum power, the lifetime is increased by a factor of three.
    what about over years of usage of LIDAR gun, will its output powers decrease? This is just one rumor i heard and i would like to have some professional clarification.

    thanks...

  5. #5
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    Quote Originally Posted by ronsc1985
    Depends on how well the designer followed the maximum operating constraints. In high power, short pulse width, very slow rep rate applications of pretty much any semiconductor the constraints much be closely followed. In a lot of cases even the manufacturer doesn't know for sure where the limit is. Heat is a factor but the heat you can measure at the outside of the device may have little to do with the heat internally (instantaneous junction temperatures) when operated in the above manner.

    There are methods to measure this but I have no idea if the diode manufacturers have done any of this work. I would doubt it since I would guess the market for these type of laser diodes in not all that big.

    You might want to ask any laser jammer manufacturer what his design test method was. For instance did he run the jammer by detecting a laser gun and then jamming with a reasonable jam length and then keep repeating this process with a reasonable interval between test cycles.

    Given the relatively poor reliability of some jammers that has been reported on this site I doubt many if any go through this process. The current method of operation seems to be "oh it broke? I'll send you a new one or at least some new components". To my way of thinking this is a poor method of operation but maybe that is the only method this low volume business can support.
    i guess we can expect a good life span of a diode jammer, since we have not heard any LEO complaining on their LIDAR guns died after years of intensive usage?

  6. #6
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    Quote Originally Posted by 1919
    Quote Originally Posted by ronsc1985
    Depends on how well the designer followed the maximum operating constraints. In high power, short pulse width, very slow rep rate applications of pretty much any semiconductor the constraints much be closely followed. In a lot of cases even the manufacturer doesn't know for sure where the limit is. Heat is a factor but the heat you can measure at the outside of the device may have little to do with the heat internally (instantaneous junction temperatures) when operated in the above manner.

    There are methods to measure this but I have no idea if the diode manufacturers have done any of this work. I would doubt it since I would guess the market for these type of laser diodes in not all that big.

    You might want to ask any laser jammer manufacturer what his design test method was. For instance did he run the jammer by detecting a laser gun and then jamming with a reasonable jam length and then keep repeating this process with a reasonable interval between test cycles.

    Given the relatively poor reliability of some jammers that has been reported on this site I doubt many if any go through this process. The current method of operation seems to be "oh it broke? I'll send you a new one or at least some new components". To my way of thinking this is a poor method of operation but maybe that is the only method this low volume business can support.
    i guess we can expect a good life span of a diode jammer, since we have not heard any LEO complaining on their LIDAR guns died after years of intensive usage?
    Hard to say. Quite a few people have reported short term reliability problems with various laser jammers on this site. I don't know if any LEO problems would get a public airing. The cost differential between laser guns and laser jammers is quite wide. This should allow the guns to be much better designed and tested.

 

 

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