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Calcite deviation between rray and oray 
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#1
Jan2912, 01:53 PM

P: 122

One explanation of the deviation of oray and eray is done using Huygen's wave fronts which for the oray is a circle and for the eray is and ellipse. The ellipse is given by the two refraction induces of 1.658 and 1.486 (http://physics.info/refraction/)
are "a" (major axis) and "b" (minor axis) respectively. I have read in several places that the maximum deviation of the oray and eray is about 6 degrees. However when I do the calculation for the angular difference for the same tangent using Huygen's wave fronts (a circle and ellipse) I only get a maximum angular deviation of about 3 degrees. Can anyone explain the difference, which obviously includes some possible error of mine? NOTE: As, for example, in the following equations, the square root only gives positive values the equations require the addition of "" to put the results in the correct quadrant. The ellipses I used had the angle from the major axis which I put along the yaxix; given the tangent angle Ang the tangent line equation is y = Ang*x + sqrt(Ang^2*b^2+a^2) The x coordinate of the point on the ellipse is x =  [ sqrt( (b^4*a^2) / ( tan(Ang)^2 a^4 + b^2*a^2 ) ) ] where the "" comes in because the positive slopes are to the left of zero. One then uses the radian arcsin of "(x/b)" to get the angle to that tangent point (TangentAngle =arcsin(x/b)*180/\pi). Subtracting the starting (circle tangent) AngTangentAngle gives you the deviation. The maximum deviation is at ~46.568 where the asymmetry is due to the "stretching" along the "a" direction. Any experimental measurement of the maximum deviation angle will be appreciated. 


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