Calculating the heating effect of a Class IV laser

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SUMMARY

The discussion focuses on calculating the heating effect of Class IV ND:YAG lasers on target materials. Key specifications include a laser output energy of <300 mJ at 1.06 μm and a repetition rate of 20 Hz. The temperature increase is primarily determined by the absorbed energy, with the need for specific equations to quantify the surface temperature within the laser beam. Participants emphasize the importance of understanding energy absorption to accurately predict temperature changes during laser operation.

PREREQUISITES
  • Understanding of laser physics, specifically ND:YAG laser characteristics
  • Knowledge of thermal dynamics and heat transfer principles
  • Familiarity with energy absorption coefficients of materials
  • Basic proficiency in using equations related to heat transfer and energy calculations
NEXT STEPS
  • Research the energy absorption coefficients for various materials when exposed to ND:YAG lasers
  • Study the heat transfer equations relevant to pulsed laser heating
  • Explore the effects of beam divergence on temperature distribution within the laser beam
  • Learn about thermal response times of materials under laser irradiation
USEFUL FOR

This discussion is beneficial for mechanical engineers, optical engineers, and researchers involved in laser applications, particularly those focused on material interactions with laser energy.

alex111888
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Hi guys,

I am of a Mechanical Engineering background, however my dissertation has a largely optics based focus, and I am struggling with understanding the heating effect of a Laser.

I will be using various wavelength ND:Yag lasers, and will be focussing them onto a target material, which I have not yet decided upon. I need to be able to calculate the heating effect of the laser on this material.

For example, if I pulse the laser constantly for 2 seconds, what will be the temperature increase of the material?

For argument's sake, we could consider the laser to be of these specifications:

Dimensions
Laser transmitter 325 x 201 x 119 mm
Laser receiver 105 x 77 x 23 mm
Mass
Laser transmitter < 7.5 kg
Laser receiver < 0.5 kg
Aperture
10 mm
Beam Divergence
Tactical @ 1.06 μm < 1 mRad
Output Energy
< 300 mJ @ 1.06 μm
< 90 mJ @ 1.57 μm
Repetition Rate
20 Hz (on both wavelengths)
Average Power
< 325 W

Thank you very much for your input.

Alex
 
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The temperature increase will be driven by the amount of absorbed energy, nothing more- unless the pulse is of ~fs duration.
 
thank you for your reply. I am ultimately looking for the surface temperature within the beam of the laser. As surely the part inside the beam will become much hotter than that outside? also- do you have any kind of equations that would be appropriate?