What Is a Diode Array?
A diode array is a type of photodetector that can simultaneously detect light intensity at multiple locations by arranging photodiodes in an array.
The wavelength of light that can be detected varies depending on the material used. The most commonly used diode array in the visible region is a silicon-based diode array that can detect light from 190 nm to 1100 nm. Diodes made of germanium, gallium, and arsenic are also available, and diodes made of lead sulfide can detect light in the infrared region (~3500 nm).
Arrays can be arranged along the wavelength axis for simultaneous multi-wavelength measurement.
Uses of Diode Arrays
Diode arrays are used in light position detection, imaging such as CCD cameras, and in the detector part of spectrophotometers and liquid chromatography.
A diode array, called a stripe detector, has stripes of several microns to several tens of microns on the substrate, enabling position detection on a micron scale.
A spectrometer that has a single photodiode as a detector and outputs a single wavelength data is called a monochromator, while a spectrometer that can output multiple wavelength data simultaneously using a diode array is called a polychromator.
Principle of Diode Arrays
Detectors using diode arrays that can perform one- or two-dimensional imaging detection, such as CCD and CMOS cameras, can simultaneously measure absorption at multiple wavelengths, making it possible to simultaneously measure mutations in samples for which absorption at any wavelength is unknown or samples that react at multiple wavelengths at the same time. Therefore, it is possible to simultaneously measure mutations in samples for which it is not known at which wavelength absorption will occur or samples that react at multiple wavelengths simultaneously.
With a single diode, it is necessary to identify the wavelength at which the mutation occurs before looking at the mutation, but with a diode array, it is possible to identify the wavelength at which the mutation occurs and to detect the actual mutation process at the same time.
The diodes that make up the diode array are less sensitive than photomultiplier tubes, but they are very stable as detectors and have a wide range of detectable wavelengths. In addition, the use of avalanche photodiode arrays, which can achieve high sensitivity, makes it possible to achieve high sensitivity, so they are used in a wide variety of measuring instruments.