Electro-Optics Handbook, Second Edition
Developed by a towering figure in the field, this valuable, all-inclusive guide thoroughly explains and discusses the use of optical devices and light in electronics systems.
TABLE OF CONTENTS Electro-Optics Handbook, Second Edition
Chapter 16: VISIBLE DETECTORS
Suzanne C. Stotlar
16.1 INTRODUCTION
The physical universe is made up of objects with temperatures greater than absolute zero, which means that the atoms and molecules of an object are in motion. These motions result in interactions with other atoms and molecules (via bonds and collisions). Therefore, these elementary particles are subject to accelerations which result in electromagnetic radiation.
Radiometry is the science of measurement of the electromagnetic spectrum. Information is obtained and evaluated by detection1 of the electromagnetic radiation on which it is impressed. This chapter discusses those detectors which provide a response to that portion of the electromagnetic spectrum which is visible to the human eye. Applications for detectors in this region are often related to human response, i.e., turning on lights when the sky is dark (to us), verifying the color purity of a paint or cloth sample, reading a printed page, or aiding in exploratory surgery. The visible spectral region lies between violet light of wavelength 400 nm to red at 700 nm. The detectors encompassed here include those most important by application and availability.
Performance Parameters
Responsivity is the response per unit of incident power. Generally, the (current) responsivity is given in amperes per watt, since more detectors are current sources. Voltage responsivity requires a knowledge of load (and frequency) conditions. Spectral responsivity is the responsivity at a specific wavelength. Most detectors, especially semiconductor detectors, exhibit some variation with wavelength.
Quantum efficiency is the fraction of photoelectrons created per incident photon, or
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