An optical detector, also known as an optical sensor or photodetector, is a device for detecting the presence or intensity of light. An optical sensor is a type of optical sensor that converts mainly into an electrical signal in response to a specific wavelength or intensity of light.

Optical detectors come in many different types and principles of operation. The most common types of optical detectors are:

Photocell or photoresist: operates on the principle that the resistance value changes in response to the intensity of light. As the intensity of light decreases, the electrical resistance increases, and as the intensity of light increases, the electrical resistance decreases. This change in resistance detects the presence of light.

Photodiode: It operates on the principle that current is generated according to the wavelength of light. When light of a particular wavelength is irradiated onto a photodiode, an electron-hole pair is generated and converted into an electrical signal. The photodiode consists of a semiconductor device, and its sensitivity varies with the wavelength of light.

Photovoltaic Converter: Works on the principle of converting light energy directly into electrical energy. The photo-voltage converter is configured in the same form as a solar panel, and the electron-hole pair generated by the light generates a voltage.

Optical detectors are used in a variety of applications. For example, optical sensors detect the presence or intensity of light in lighting control, automotive lighting systems, optical communication systems, industrial automation, medical devices, etc., and are used for control or measurement. In addition, optical detectors are also used in various fields such as optical switches, optical fiber sensors, and photobiological studies.