Detector: The detector is a device that measures the intensity of light after it has passed through the sample. There are various types of detectors used in spectrophotometers, including photodiodes, photomultiplier tubes, and charge-coupled devices (CCDs). Types of photoelectric conversion include the external photoelectric effect, a prominent form of which is photoelectric. The selection of detectors in a spectrometer is crucial and is usually based on factors such as wavelength range, detection sensitivity, and resolution requirements.