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Unformatted text preview: 1 125:431 Introduction to Optical Imaging Spring 2007 Problem set #2 Due Tuesday Feb. 6 Related readings: Hecht Sections 3.3 and 13.1, and reference posted on WebCT under resources for Pb set 2 1. Consider again the E field vector z t kx E y t kx E E o o ˆ ) cos( ˆ ) cos( ω ω − − − = r which satisfies the wave equation: 2 2 2 t E E o o ∂ ∂ = ∇ r r µ ε Write an expression for the Poynting vector average, < S > T , calculated over a time interval T, such that ω T>> 1 2. A researcher observing green fluorescent protein detects an average of 100 counts per pixel on a CCD camera in her microscope. The data acquisition time was 10ms. a. Assuming that every count on this CCD correspond to 5 photons at 514nm, what is the average optical power (in watts) measured per pixel? b. Assuming that the detected photons follow a Poisson probability distribution, and that there is no other significant source of noise in the system, what would you estimate the signaltonoise ratio to be per pixel? c. How would you improve the signal to noise ratio? 3. This problem was adapted from the paper entitled: “A computer model of laser action in the teaching of computational Physics” by D.G.H. Andrews and D.R. Tilley, Am. J. Phys, 59 (6); 536541, June 1991 ( posted on WebCT in the resources link, Resource for Problem Set 2 ) Consider the following 4 level system (see figure) with the following rate equations: dN 1 /dT= N 1 /T 1 + A 21 N 2 + B 21 (N 2N 1 )W, for the lower state 1, 2...
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This homework help was uploaded on 04/03/2008 for the course BIOMEDICAL 431 taught by Professor Boustany during the Spring '07 term at Rutgers.
 Spring '07
 Boustany

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