A ruby laser emits pulses of coherent monochromatic light of wavelength λ=694 nm, with a power of 35
Physics

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A ruby laser emits pulses of coherent monochromatic light of wavelength λ=694 nm, with a power of 35.0 kW. Each pulse lasts 0.800 millisecond and can be seen as a beam 5.00 mm in diameter, which fulfills Gauss’s condition. It is aimed at the surface of the Moon, which, from the Earth’s surface, is between 354,994 km and 397,586 km away. If we want the area illuminated at the Moon to be a disc of at least 6,500 meters in diameter, what should be the focal length of the diverging lens used? Draw a raytracing diagram of the system with one diverging lens (not to scale!) Assuming a planarconcave lens is used, what would be the radius of curvature of the concave side (assume flint glass of n≈1.66)? Comment on the result. Instead of a single lens, a pair of convex and concave lenses are placed very close to one another. Calculate the spacing required to achieve the focal length of question 1 using a ±1.00 dp pair of lenses. What is the approximate number of photons received by an object that is about 1 m2 in area within the region illuminated by the laser, if only 1.00% of the photons emitted travel past the Earth’s atmosphere towards the moon?
uby laser emits pulses of coherent monochromatic light of wavelength
λ=694 nm, with a power of
35.0 kW. Each pulse lasts 0.800 millisecond and can be seen as a beam
5.00 mm in diameter, which fulfills Gauss’s condition. It is aimed at
the surface of the Moon, which, from the Earth’s surface, is between
354,994 km and 397,586 km away.
If we want the area illuminated at the Moon to be a disc of at least
6,500 meters in diameter, what should be the focal length of the
diverging lens used
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