Is 532nm the Optimum Wavelength for Atmospheric Particle Tracking?

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SUMMARY

The discussion centers on the use of 532nm wavelength for atmospheric particle tracking using pulsed Lidars. Participants clarify that the power values listed in scientific papers typically refer to the energy per pulse rather than total energy over time. The conversation highlights the importance of understanding pulse energy, pulse repetition frequency (PRF), and the implications of using 532nm as an optimal wavelength due to its cost-effectiveness and compatibility with high-power visible lasers. The consensus is that 532nm is indeed optimal for Lidar applications compared to other wavelengths like 514nm or 1064nm.

PREREQUISITES
  • Understanding of pulsed Lidar technology
  • Familiarity with pulse energy and power calculations
  • Knowledge of pulse repetition frequency (PRF) and pulse repetition time (PRT)
  • Basic principles of laser operation and wavelength selection
NEXT STEPS
  • Research the principles of pulsed Lidar systems and their applications
  • Learn about energy per pulse calculations and their significance in Lidar
  • Explore the differences between Lidar and radar technologies
  • Investigate the impact of wavelength selection on atmospheric particle tracking
USEFUL FOR

This discussion is beneficial for optical engineers, Lidar system designers, and researchers in atmospheric sciences who are involved in the development and optimization of Lidar technologies for particle tracking.

pyroartist
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TL;DR
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.
If you have a link for this answer I would like to see it please.
Thanks.
 
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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.

BTW: I didn't read your link, so I may have misunderstood something.
 
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pyroartist said:
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.
 
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From the article:

1608740596249.png


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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Klystron said:
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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Most likely this can only be answered by an "old timer". I am making measurements on an uA709 op amp (metal can). I would like to calculate the frequency rolloff curves (I can measure them). I assume the compensation is via the miller effect. To do the calculations I would need to know the gain of the transistors and the effective resistance seen at the compensation terminals, not including the values I put there. Anyone know those values?

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