An optical filter is an optical component that is used to transmit or reflect a specific range of wavelengths or a specific proportion of the incident light. It can be identified as a colour. The transmission of the light is considered as absorbed or cut. They are also applied as an absorbtion of light, use to pass long wavelengths only (longpass), short wavelengths only (shortpass), or a band of wavelengths, blocking both longer and shorter wavelengths (bandpass). Some of the most current and prominent applications that use filters are flow cytometry, Raman spectroscopy, fluorescence microscopy, LiDAR, imaging, astronomy, and various laser applications.