Deflectometry is a non-contact optical metrology technique used to measure surface shapes and imperfections. This technique relies on analyzing the reflection of a known pattern of light from a surface to determine its shape and deviations. Deflectometry is commonly used in industries such as aerospace, automotive, and optics for quality control and inspection of reflective surfaces. It is a fast and accurate method that can provide detailed information about surface roughness, curvature, and other parameters. Overall, deflectometry is a powerful tool for measuring and analyzing surface shapes and imperfections with high precision and resolution.