Patent ID: 8400631

Claim:
A method for measuring a wave surface derived from a zone of a face of an optical component formed of a stack including a substrate and at least one layer having different refraction indices, wherein the method includes the following steps: a) measuring, at a reference point M O located in the zone of the face of the optical component, a spectral response of the said reference point as a function of a wavelength of a light passing through the said reference point, and grouping together the measurements obtained in this manner in a spectrum representing the spectral response as a function of the wavelength; b) in the spectrum obtained in step a), determining a range of wavelengths which gives the greatest difference between a successive minimum and maximum, or between a successive maximum and minimum of the spectral response and selecting a wavelength, and selecting a wavelength, wavelength, called a measurement wavelength, from among the determined range of wavelengths; c) measuring the spectral response of n measuring points M i located in the said zone, where n is an integer greater than or equal to 1, at the measurement wavelength λ meas : RSP (Mi) (λ meas ): d) among the measurements obtained in step c), determining an average spectral response to the measurement wavelength: RSP av (λ meas ); e) in the spectrum of reference point M O obtained in step a), determining the average wavelength λ av such that RSP Ref(Mo) (λ meas ); f) for each of the n points M i , with i=1 to n: 1) determining a wavelength λ i such that the spectral response at point M i to the measurement wavelength is equal to the spectral response at reference point M O to the wavelength λ i : RSP Mi (λ meas )= RSP Ref(Mo) (λ i ) 2) calculating a difference between a wave number σi (σi=I/λi) and the average wave number σ av (σ av =1/λ av ): Δσ i =σ i −σ av 3) determining a real centering wave number σ j at point Mi: σ j =σcentering+Δσ i with σ centering =1/λ centering and λ centering being a centering wavelength of the optical component; 4) calculating a wavelength λ j corresponding to the real centering wave number at point M i : λ j =1/σ j 5) calculating a phase difference Δφ Mi existing between a real centering phase and a theoretical centering phase at the centering wavelength: ΔΦ Mi =Φ(λ j )−Φ(λ centering ) 6) calculating a path difference δ i existing at point M i at the centering wavelength: δ i =ΔΦ Mi ×λ centring /(2π).