Question

(a)

What is the minimum angular spread (in rad) of a 431 nm wavelength strontium vapor laser beam that is originally 1.56 mm in diameter?

rad

(b)

If this laser is aimed at a mountain cliff 16.0 km away, how big will the illuminated spot be? (Give the diameter of the spot in meters.)

m

(c)

How big a spot would be illuminated on the Moon, neglecting atmospheric effects? (This might be done to hit a corner reflector to measure the round-trip time and, hence, distance. Assume the distance from the surface of the Earth to the surface of the Moon is 3.82 ✕ 10⁸ m. Give the diameter of the spot in kilometers.)

km

(d)

If you have completely polarized light of intensity 170 W/m², what will its intensity be after passing through a polarizing filter with its axis at an 87.0° angle to the light's polarization direction?

mW/m²

Answer 1

Ca) 1 : 4317 d = 1.57 mm Now 0 - 1.22 = 1.224 431X1009 1.568163 0 = 3.37x10 " radian - - (b) d = 16.0 km - How timal diameter would be equal to ax+ D. and tan o = 2 so x : tonoxD we know tano no De = OxD x = 3.37x164X16X/03 x = 5.39 km rowe gse+ D 2 / 5.99) + 1856X10-3 - I Qxt D = 10.78 ml (c) d = 3082x108 x = 0x D = 3.37x10=4x 3.88 x168 x = 19.8734x 10 m 1992 = 257. S tem Jz lo cogido I = 17ox cay (87") I: 0.46 m2 CS Scanned with CamScanner