Pulsed Lidar power specs?

• pyroartist

pyroartist

TL;DR Summary
Looking for the definition of a term.
In reading scientific papers on atmospheric pulsed Lidars there is often a table that includes system information such as the type of laser, the power in uJ or mJ and the rep rate. Examples of the power would be usually somewhere between 50 uJ and 30 mJ. Rep rates are between 10 and 10,000 pulses a second. Here is just one of many such articles:
http://www.scielo.org.za/scielo.php?pid=S0038-23532009000600018&script=sci_arttext
My question: Is the power listed the value for each pulse or is it the total of the pulses in one second? This has never been made clear in any article so it must be commonly known among Lidar engineers.
Thanks.

If the author does it they way most laser people do, then it's the energy in each pulse. It's just too confusing to talk about the energy in 10, 100, or 1000 pulses, then you would have to also say how many pulses in your definition. Everyone with any sense will default to 1 pulse.

berkeman
Examples of the power would be usually somewhere between 50 uJ and 30 mJ. Rep rates are between 10 and 10,000 pulses a second.
The unit of energy is the joule. The rate of energy flow is power in watts.
A pulse energy of 1mJ repeated 100 times per second would be 100mJ/sec = 100mW.
The power of one pulse is less meaningful. It would be the pulse energy divided by the pulse duration.

berkeman
From the article:

The author states that optimum wavelength to track atmospheric particles determined system design; thus, lidar instead of radar. Average pulse energy refers to multiple pulses over time with attention to beam expansion and divergence at intended target ranges.

Consider also the maximum unambiguous range of pulsed transmit/receive systems. This allows one to optimize PRF/PRT (pulse repetition frequency and its reciprocal, pulse repetition time) depending on required range and vice-versa. The linked calculator applies to radar, lidar and some acoustic models.

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optimum wavelength to track atmospheric particles
LOL, ok. What an unusual coincidence that it landed on/near 532nm, which is the very cheapest (i.e. easiest) wavelength to generate in high power visible lasers, and one that Continuum is good at doing. Thank god they didn't land on 514nm where they might have needed an Ar-Ion laser! Too bad it didn't land on 1064nm which is even cheaper.

OTOH, they said lidar vs. radar. Which is at least a factor of a thousand difference. So, OK, I guess it's optimum by some definition.

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