Chapter 5
Fundamentals of Optical Detectors
Abstract The photodetection devices used in biophotonics disciplines are
semiconductor-basedpinand avalanche photodiodes, photomultiplier tubes, and
optical detector arrays. The photodetectors can be either single-channel elements or
multichannel devices. With a single-channel element only one spectral channel in a
biophotonics setup can be monitored at any instance in time. However, multi-
channel devices can measure multiple spectral channels simultaneously or observe
spatial channels individually in different time sequences. Associated with pho-
todetection setups is the need for opticalfilters, optical couplers, and optical cir-
culators. Opticalfilters selectively transmit light in one or more specific bands of
wavelengths. Optical couplers split or combine two or more light streams, tap off a
small portion of optical power for monitoring purposes, or transfer a selective range
of optical power. An optical circulator is a non-reciprocal multi-port device that
directs light sequentially from port to port in only one direction.
A photodetection device is an essential and crucial element in most biophotonics
disciplines that involve light sensing and analysis. Among the photodetection
devices covered in this chapter are semiconductor-basedpinand avalanche pho-
todiodes, photomultiplier tubes, and detector arrays based on complementary metal-
oxide-semiconductor (CMOS) and charge-coupled device (CCD) technologies. The
photodetectors can be either single-channel elements or multichannel devices
consisting of one-dimensional rows or two-dimensional arrays of detectors. With a
single-channel element only one spectral channel can be monitored at any instance
in time. However, multichannel devices can measure multiple spectral channels or
examine spatial channels individually in different time sequences. Multichannel
devices enable the simultaneous monitoring of a wide spectrum of multiple indi-
vidual wavelengths or narrow spectral channels.
©Springer Science+Business Media Singapore 2016
G. Keiser,Biophotonics, Graduate Texts in Physics,
DOI 10.1007/978-981-10-0945-7_5
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