1. In “24” Jack Bauer hopes to use spy satelliteimaging to hunt down the bad guy

Question

1. In “24” Jack Bauer hopes to use spy satelliteimaging to hunt down the bad guys. Your mission is to applyphysical optics, namely the Rayleigh criterion: sinq=1.22l/a (seechap 32 probs 52 & 53), to help Jack determine if he should beable to a) read a license plate on a get-away car, b) only ID thetype of car or c) at least determine the building the car pullsinto. You will need to estimate or research reasonable parametervalues to help him with this mission.

2. In one episode of “24” Jack uses spy-satelliteinfrared imaging to “see” the bad guys at night in thedark.

a) Compare the resolution of these images to those taken by thesame satellite but using visible light during the day.

b) What are the advantages/disadvantages of the two imagingmodalities?

3. Are there other factors that affect the resolution of a spysatellite (how)?

Explanation / Answer

1.a)the Rayleigh criterion: sinq=1.22l/a When the central maximum of one image falls on the firstminimum of another image,the images are said to be justresolved.This limiting condition of resolution is known asRayleigh's criterion. The first minimum in a single-slit diffraction pattern occursat the angle for which sin = (/a) 2.According to Raleigh's criterion,this expression givesthe smallest angular separation for which the two images areresolved.Becasue << a in most situations,sin issmall and we can use the approximation sin ˜.Therefore,the limiting angle of resolution for a slit ofwidth a is min = (/a) 3.Other factors that affect the resolution of a spy satelliteis the use of a diffraction grating.The diffraction grating,auseful device for analyzing light sources,consists of a largenumber of equally spaced parallel slits.The condition for maxima inthe interference pattern at the angle brightis d * sinbright= m * m =0,±1,±2,±3,...................

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