# HW10+SOL - Solution 10 1. An electro-optical tunable...

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Solution 10 1. An electro-optical tunable retarder ( Kerr-cell) is able to produce from linear polarized light ( λ = 5145 Å) circular polarized light by a retardation of = λ /4 when being switched from zero to E = 1200 volts/cm. What switching voltage must be applied in order to use the Kerr-cell as a shutter to switch on and off the linearly polarized light from an argon laser with λ = 5145 Å? Make sketch of electro-optical arrangement used and the relevant light polarization. To make a shutter for a linearly polarized light, we need a tunable λ /2-retarder and a linear polarizer. The polarization of the linearly polarized light can be changed 90° by the tunable λ /2-retarder, and the light is blocked by or transmitted through the linear polarizer. For a Kerr cell, the retardation Δ = d· Δ n = d· λ o ·K·E 2 . When Δ = λ /4, we need E = 1200 volts/cm. Therefore, in order to get Δ = λ /2, we need E = 2 · 1200 volts/cm. = 1697 volts/cm Laser E= 1697 V/cm E = 0 No Light

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100 atm its refractive index n in the following way: (a) n || (100 atm) = + 8.5 × 10 -5 for light polarized parallel to the compression direction. (b) n (100 atm) = – 3.0 × 10 -5 for light polarized perpendicular to the compression direction. How much uniaxial pressure do you have to apply if you want to obtain circular polarized light from linearly polarized light of λ = 6500 Å? Make a sketch of arrangement, and show what you would do (with the same elements) in order to change between right and left circular polarized light? For the stress-birefringent material, Δ n = ( n || n ) = α S. Since Δ n = 1.15 × 10 -4 for S = 100 atm, the constant α is α = 1.15 × 10 -6 atm -1 . In order to obtain circular polarized light from linearly polarized light, we need a λ /4-retarder for λ = 6500 Å. The retardation is given by Δ = d · Δ n = d · α · S , so that S = Δ α = λ 4·d· α = 6.5 10 -7 (m) 4 · 1.5 10 -2 (m) · 1.15 10 -6 (atm -1 ) = 9.42 atm With the same arrangement, if you want to change from right to left circular polarized light, we need to apply more pressure to make Δ = 3 λ /4, that is, to increase the pressure S = 28.3 atm . Laser
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## This note was uploaded on 08/06/2008 for the course PHYS 352 taught by Professor Dierolf during the Fall '04 term at Lehigh University .

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HW10+SOL - Solution 10 1. An electro-optical tunable...

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