A modern optical spectrometer functions as a precision photon-sorting instrument. Light reflected, transmitted, or emitted from a sample enters through a micron-calibrated entrance slit, which establishes the spatial resolution and optical throughput of the system.
Inside, a collimating mirror aligns the incoming beam into parallel rays directed toward a diffraction grating etched with thousands of microscopic grooves per millimeter. This grating disperses the beam into individual component wavelengths, focused by a camera mirror onto a semiconductor detector array.
Each pixel on the detector corresponds to a calibrated wavelength channel. Onboard microcontrollers digitize the integrated electrical charge across thousands of pixels in milliseconds, generating a high-fidelity digital spectrum ready for computational analysis.