The CRD High Reflectivity Meter (CRD High Reflectivity Measurement) is a precision Optical Testing device based on Cavity Ring-Down Spectroscopy (CRDS). Two high-Reflection cavity mirror composition Optics resonant cavity, when a beam of pulse Laser along the Optical Axis incident into the cavity, ignoring the Diffraction and scattering losses, a single pulse Laser in the two cavity mirrors between the back and forth oscillation, to comply with the single exponential decay law, the measured reflectivity is the ring-down time function. Therefore, to obtain the ring-down time, you can determine the sample reflectance. We developed the CRD high reflectivity measuring instrument measuring reflectivity range of 99.9-99.995%, support 0 ° or 45 ° Incident Angle measurement, can be customized according to the user sample size. Its high sensitivity and anti-interference characteristics make it an ultra-low loss Optics component quality control ideal tool, such as Laser Source resonator, Optics film and other industrial and scientific research fields.