Final answer:
The light-sensitive chip in modern optical telescopes is known as a charge-coupled device (CCD). It detects electromagnetic radiation and converts it into a digital image. CCDs offer high sensitivity and efficiency in capturing faint lights from distant astronomical objects.
Step-by-step explanation:
The light-sensitive chip found in modern optical telescopes is called a charge-coupled device (CCD). A CCD is an array of high-sensitivity electronic detectors of electromagnetic radiation, used at the focus of a telescope to record an image or spectrum. When radiation in the form of photons hits the detector, it generates a stream of charged particles (electrons), which are stored and then counted at the end of the exposure. Each area where the radiation is counted is known as a pixel (picture element), and modern CCDs can contain millions of these pixels, allowing for the detection and imaging of astronomical objects at megapixel resolution.
CCDs are more efficient than photographic plates or film, used previously, because they can detect a higher percentage of the incoming photons and maintain their sensitivity over a wider range of wavelengths. This efficiency is crucial in astronomy, where capturing faint light from distant objects is often necessary.
To observe at infrared wavelengths, specialized detectors that are cooled to very low temperatures are used to minimize the infrared radiation emitted by the telescope itself and other nearby objects, which could overwhelm the faint signals from celestial sources. A spectrometer is then used to disperse the light into a spectrum for detailed analysis.