Physics 21Fall, 2004Solution to HW-2736P21The normal lens of a 35 mm camera has a fo-cal length of 50 mm.Its aperture diameter varies from amaximum of 25 mm (f/2) to a minimum of 3.0 mm (16).Determine the resolution limit set by diFraction for2and16. Specify as the number of lines per millimeter resolvedon the ±lm. Takeλ= 500 nm.²or a lens diametera, the angular distance from the cen-ter of the diFraction pattern of a line to the ±rst zero willbe 1.22λ/a. Assuming the lens is focussed at in±nity, thedistance to the ±lm will be the focal lengthf, so the actualdistance will be 1.22fλ/a. This distance is the closest spac-ing of two just-resolved lines. The number of lines per unitlengthNresolvable on the ±lm will be the reciprocal of thisdistance,N=a1.22fλ.²orf=50mmandλ= 500 nm,a=25mm⇒820/mm,a=3mm⇒98/mm.36P34Missing orders occur for a diFraction grating whena diFraction minimum coincides with an interference maxi-mum. Letabe the width of each slit anddthe separation of
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This note was uploaded on 08/06/2008 for the course PHYS 21 taught by Professor Hickman during the Fall '07 term at Lehigh University .