Spectroscopy is the study of matter by investigating light, sound, or particles that are emitted, absorbed, or scattered by the matter under investigation. Spectroscopy is often used in physical and analytical chemistry for the identification of a substance through the spectrum emitted or absorbed by the sample. A device for recording a spectrum is a spectrometer. There are a large number of different design approaches for spectrometers. One of the most common approaches is based on interference filter technology. JDSU has a wide array of filters that are used in spectrometers and related instruments. JDSU bandpass filters, linear-variable filters, and edge-bonded filters can be designed to customer specifications to optimize system performance.