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**Summary:**Need to calculate the fluence of Gaussian Laser Beam: laser tip 1 cm above surface, tilted at 45 0 angle to surface.

Need to calculate the fluence of Gaussian Laser Beam: laser tip 1 cm above surface, tilted at 45 0 angle to surface.

Laser tip size 1 mm across

Diameter 0.5 mm

Surface area = pi r 2

3.14 x (0.5)2

0.79 mm 2

= 0.0079 cm 2

Beam diverts 6 degrees both sides of tip

tan 6 0 = 0.11 cm (base of triangle)

Triangle surface = 1/2 x base x height

= 0.055 cm 2

Total surface = (0.055 cm 2 x 2 ) + 0.0079 cm 2

= 0.1179 cm 2

45 0 angle: cosin 45 0 = 0.707

Total surface 0.1179 cm² ÷ cos 45°

= 0.17 cm²

Pulse Energy = P(average) ÷ Pulse Frequency

= 0.5 W ÷ 30 Hz

= 0.01667 J

Fluence = Energy of laser pulse / Area of spot

= 0.01667 J / 0.17 cm 2

= 0.0980 J/cm² ( area is irradiated for 30 seconds)

( do I multiply ?? x 30 s)

= 2.94 J/cm² (??)

Fluence = (average power) / rep rate/ spot area

= 30 Hz / 0.17cm^2 x 0.5 W

=88.24 J/cm^2 ( ??)

Please help!

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