Patent ID: 6894788

Claim:
An interferometric system for measuring a radius of curvature of a measurement object, said system comprising: a tunable coherent radiation source capable of emitting a radiant energy beam having a characteristic wavelength and of scanning the characteristic wavelength over a range of wavelengths; an unequal path interferometer which during operation includes a reference object and the measurement object and which receives a portion of the radiant energy beam from the tunable radiant energy source and generates an optical interference pattern; a detecting system including a detector for receiving the optical interference pattern; a system controller connected to the tunable radiant energy source and the detecting system, said controller programmed to cause the tunable radiant energy source to scan the characteristic wavelength over said range of wavelengths while concurrently monitoring the optical interference pattern via the detecting system and further programmed to calculate the radius of curvature of a surface of the measurement object from the monitored optical interference pattern; and a wavelength change monitor configured to monitor changes in the characteristic wavelength of the radiant energy source, wherein said system controller is arranged to receive output from the wavelength change monitor and is programmed to calculate the radius of curvature of the surface of the measurement object from a monitored change in the wavelength and the monitored optical interference pattern.