LASIK eye surgery uses pulses of laser light to shave off tissue from the cornea

Question

LASIK eye surgery uses pulses of laser light to shave off tissue from the cornea, reshaping it. A typical LASIK laser emits a 1.0-mm-diameter laser beam with a wavelength of 193 nm. Each laser pulse lasts 20ns and contains 1.7mJ of light energy.

What is the power of one laser pulse?

Express your answer to two significant figures and include the appropriate units.

Part B

During the very brief time of the pulse, what is the intensity of the light wave?

Express your answer to two significant figures and include the appropriate units.

Explanation / Answer

A)
Power= work / time, work is in joules time is in seconds

(1.4*10^-3 j) / (19*10^-9seconds) = 73.684 kW, or 74 kW

So the answer for part a is 74 kW

B) Intensity = power per unit area

area = pi * r^2

r = .0005m

Intensity = 74kW / (pi * 0.0005m^2) = 9.4 * 10^7 kW/m^2

So the answer for part B is 9.4 * 10^7 kW/m^2

Your professor might use a different formula for area of a beam, thats the only one that makes sense to me though.

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