Thin film coating analysis using a novel IR camera and a broadband Echelle spectrograph

An echelle spectrograph can provide high resolving power (wavelength/FWHM) across a broad spectral range. These optical instruments are commonly used in spectroscopy for atomic and molecular identification in astronomical observations and laboratory analysis. The wavelength range of an echelle spectrograph is ultimately limited by the capabilities of the detector used to acquire the spectral data. Silicon based CCD, EMCCD and CMOS sensors typically enable measurements from 200nm to 1100nm. Infrared Laboratories and Catalina Scientific Instruments (CSI) have collaborated to demonstrate an application that combines IR Lab’s TRIWAVE camera with CSI’s EMU120/65 echelle spectrograph. The TRIWAVE camera covers a spectral range of 300nm to 1600nm, greatly increasing the wavelength range for applications using the EMU-120/65 spectrograph. With this increased capability, an opportunity exists for measuring the dielectric coating thickness of thin film by extracting and analyzing interference fringes from the spectral data. Methods and results of this measurement will be presented.