The energy density was calculated using this formula, Energy Density = E/A (J/cm2). Here E is the input energy measured in millijoules, A is the area of the circular spot.
E values I know from LDT analysis.
A value, How to calculate using the following parameters?
Laser Beam diameter= 8 mm
Focal length = 20 cm
Nd:YAG laser = 1064 nm
Pulse width = 10 ns
use the diffraction due to the circular aperture
Beam diameter at focal point = (1.22 x focal length x wavelength)/(beam diameter)
Beam diameter would become on substituting all values: 3.2452 x 10-3
Beam Radius = 1.6226 x 10-3
E/A = 1 x 10-3 /(3.14 x(1.6226 x 10-3)2)
E/A = 0.196 J/m2
Pulse width would not play role here, it will change the peak energy but average energy remains same, for the time being, I have chosen an energy is 1 millijoule
Dear Kirubanithy Mk ,
In general, the effective area (Aeff) is proportional to the diameter at 1/e2 or 0.135 of its peak value.
Time duration of laser pulse is needed if one need to calculate the Laser intensity. This can be obtained by dividing the energy density by the time duration of laser. It will have unit of W/cm2.
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