Does the scan speed has an effect on energy density? When the CW laser is focused to a point, the energy density is calculated by dividing Pulse energy by area of the beam spot. But if the laser is scanning at high speed (in Selective laser machining), will it be the same?
Hello,
In this case, I would calculate the so-called "surface power density", i.e. the product of the energy and its velocity, see also: https://en.wikipedia.org/wiki/Surface_power_density
The residence time of the beam will vary depending upon the scan speed. The residence time can be calculated by dividing the spot size by the scan speed. Then one can divide the energy density by the residence time to come up with a power density equivalent which will vary with scan speed. If it is a pulsed laser then the pulse repetition rate (PRF) also needs to be considered.
Srini Vasan Christoph Gerhard I need energy density in J/cm^2. I used the following method to calculate. Can you tell whether it is right or not.
Laser specification:
Power: 105 W
Mode: Continuous
Beam diameter: 200 micrometer
Scan speed: 200 mm/s
- First, I calculated the residence time of the laser spot :
Residence time (s) = Beam diameter (mm) /scan speed (mm/s)
- Then I calculated Energy
Energy (J)= Laser power (w) * Residence time (sec)
- Then I calculated the energy density:
Energy density (J/cm^2) = Energy (J) / Area (cm^2)
Christoph Gerhard
A moving laser source is used to heat the top layer of a 316 L test specimen. Can we use the following equation to calculate the surface temperature response?
I used the equation which I mentioned in the last discussion.
T (t) = T0 + Q / [e. ( π .t)^1/2]
where Q ( J/cm^2 ) is the energy absorbed by the surface of the test pieces, T0 ( 0C) is the initial
temperature, t ( s ) duration of energy input, e is the material’s effusivity.
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