
OPTICAL DETECTION 431
• Transimpedance ampliers are often used as the rst electronic stage of a detector
circuit.
• The most sensitive detectors are cooled to improve SNR.
13.5 THERMAL DETECTORS
In thermal detectors, light is absorbed, generating heat, and the rise in temperature is measured
by some means to determine the optical energy or power. Thermal detectors are often used as
power meters or energy meters.
13.5.1 Energy Detection Concept
The concept of the thermal detector is quite different from that of the photon detector.
Figure 13.1A shows the concept of a thermal detector or bolometer. A photon is absorbed,
and the energy is converted to