Question

Q3 Fresnel Relations A laser beam of 600 nm wavelength propagates in sea water (n = 1.33), striking the glass window (ng = 1.50) of a submarine at an angle of 50° with respect to normal incidence. The beam undergoes total internal reflection at the glass-air interface. laser 50° n = 1.33 ng = 1.50 Nair = 1.0 (1) [3 marks] Calculate the penetration depth of the light intensity into the air for TE polarization. (2) (4 marks] Determine the complex value of the Fresnel reflection coefficient, rre, for the glass-air interface. (3) [1 mark] If the laser beam is circularly polarized, explain why this will change on reflection from the glass-air interface.

Answer 1

Saluhan fins buti ET 89 LOXCEL = es un mu sin o 1.50 leso = 42,78

for TE polanzamen concider the diagram below fui kept Elbetric vessor is paretted to plane of incidence, glass + z 17 Tronsmoutted wave, E = E, expliikT-WE)) - Ez Camp LQ 22_6369 +& Kzęcin Eo, eup lile ky cose + zky Sind - wt)] o Now find = ng a ting = n fino Gino = "*. X 619 44.76€ = 1,018! Coso = JT- sing = istinad -I = er į - koz expli(1k, iy + z kysing -wt)? Egen € 147 exp[ izk, hing-wt] - for et explizketing - wt]

where, p = 0K2r ir sind I I penetration depth, Lco Sistonen d = tor ka = pt at x = hindi = 80.1905 arxoolsos - 6.78X 0.19.5 - 7 Id = s.olx jó meget ans S.olx 10 me e r . = EzCase find Enfine cost Ez lose find + Eg fine cord cos e Hing @ Hino Luisd . Coso Hind + er sneros de For non-magnetic material, sino no al Ea finap ng lale olete the most =).5

and, corp = iy. . fing = 10018 Ws8 0.733; fino = 0.679 SE= 0.7338 1.016 Elis80.679 i10.1905) 01733 x 1,01 g +105 X 01679110.1901) 0,7461 -0.1941. a-lbaath 0.7461 + 00194 i atib arab 9² +6²-2ah _ a?+12 0.594-0.269 i . 0,594 The ! -0,4871 ) Ang - 3 = r- V = 10²44? e o rang = = 1 / 2 total internal reflection leads to a phase change in refleted wave, this additional phase change will lead to a Change in polanzaron

i Elorellehed = = 1 EX Eencident 1799} é ' 9 x Einuiedent