Showing papers on "Photodetection published in 1975"

Optical homodyne detection

Abstract: This paper contains a theoretical treatment of optical homodyne detection applied both to radiometry and to scattering in the visible and near infra-red, together with some experimental comparisons. A signal estimator, corresponding to the difference in the detector output a.c. power when a given optical field is present or absent, is introduced. The accuracy with which the mean signal intensity can be measured is derived in terms of the inverse root relative variance (IRRV) of this estimator. It is shown that most conventional microwave-based analyses of this problem need revision since they ignore, or treat in an ad hoc manner, both signal fluctuations and photodetection quantum statistics. A rigorous analysis is given including both these effects. The predictions of this analysis compare favourably with existing experimental data. The results are then used to compare signal-intensity measurement by direct or homodyne detection under various operating conditions. Finally, going beyond the measu...

Use of a regenerative optical quantum amplifier in photodetection of scattered coherent radiation

Abstract: An experimental investigation was made of the efficiency of a regenerative optical quantum amplifier in detection of scattered laser radiation. In agreement with theoretical estimates, the experimental results demonstrated that the average energy of the scattered field amplified in this amplifier did not exceed the energy in the spatial coherence area. The relative variance of the output signal, which was distributed exponentially under linear conditions, was close to unity and was independent of the relationship between the correlation radius of the spatially random field and the receiver aperture radius.

I. Precision Measurements With a Ruby Laser. II. A Quantum Mechanical Paradox.

Abstract: PART I In attempting to make precise spectroscopic measure­ ments with a ruby laser, many problems can arise which will negate the value of the data obtained. Part I of this paper discusses many of these problems and how to eliminate them. Then the results are applied to a simple experiment, that of measuring high intensity reciprocity failure in photographic emulsions. Furthermore, it is shown that one can use a photographic emulsion in place of a photodetec­ tor for making accurate and precise measurements.