Bolometers for infrared and millimeter waves

TLDR

Bolometers evolved from early thermal detectors and are optimal for infrared and millimeter‑wave applications, though superconducting thermometers at low temperatures involve tradeoffs. This review aims to describe infrared and millimeter‑wave bolometers and equip readers to select or evaluate appropriate technologies. The authors present elementary and rigorous theories of bolometer response and noise, detail efficient bolometer components and fabrication, and focus on composite bolometers with semiconducting thermometers at liquid‑helium temperatures and high‑Tc superconductors at liquid‑nitrogen temperatures. Key results are derived simply from the laws of thermal physics.

Abstract

This review describes bolometric detectors for infrared and millimeter waves. The introduction sketches the history of modern bolometers, indicates how they fit into the more general class of thermal detectors, and describes the types of applications for which they are the optimum solution. Section I is a tutorial introduction to the elementary theories of bolometer response, of thermal radiation, and of bolometer noise. Important results are derived from the laws of thermal physics in the simplest possible way. The more rigorous theories of bolometer response and noise that are required for quantitative understanding and optimization are then summarized. This material is intended to provide the background required by workers who wish to choose the appropriate bolometer technology for a given measurement, or to evaluate a novel technology. Section II, then describes the various components of an efficient bolometer and gives details of the fabrication and performance of modern bolometers. This discussion focuses on composite bolometers with semiconducting thermometers for operation at and below liquid helium temperatures. The tradeoffs involved in using superconducting thermometers at low temperatures are discussed. Finally, a discussion is given of bolometers for operation at liquid nitrogen temperature which use the new high-Tc superconductors as thermometers.