Methods of high-resolution, high-speed, optical beam deflection and scanning are reviewed with respect to resolution and scanning frequency capabilities. A general description is given of external deflector devices in the categories of variable reflectors, variable refractors, birefringent deflectors, and interference deflectors. The different techniques are then evaluated on the basis of their application to high-speed, high-resolution, precision scanning applications.
The effect on the conductivity of germanium and silicon samples of 2.85-kMc electric fields up to peak values of 10 000 v/cm was measured. These measurements differ from earlier ones in that: (1) the microwave field was in the form of progressive rather than standing waves, which made possible more accurate determination of the field strength in the sample, and (2) to determine whether any frequency effects occur at 2.85-kMc conductivity was measured at high dc fields on the same samples. From the average conductivity under microwave excitation the instantaneous conductivity was calculated and found to agree, within experimental error, with the dc conductivity, indicating that the conductivity can still follow the 2.85-kMc field at least up to peak fields of 10 000 v/cm.
Fig. 2-Graphical presentation of the inequality (51 frequency ratio fdfi. between the dynamic quality factor yfc./fi and the With a given diode ( i e . a given -ifc) and a given pump frequency fp =fi+fz the inequality (5) is met for all signal frequencies only if the condition -d o > W P (6)holds. This condition is practically always satisfied.We have thus shown that the simultaneous use of the photo diode as a parametric amplifier diode degrades the SNR of the receiver. The underlying physical cause is the fact that in a photo paramp the photo diode in the signal circuit must be heavily mismatched, and that the shot noise of the photo current at the idler frequency is additionally transformed into the signal circuit.
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