Optimization method and device for direct measurement of an optical component

A method of measuring directly a surface topography of an optical component in a measuring system comprising the steps of:

• illuminating said optical component with incident light having a known wavefront, said light having wavefront slopes;
• measuring, in a given plane, maps of wavefront slopes of said light, after reflection off said optical component or transmission through said optical component, by determining, using a deflectometric method, paths of a plurality of rays of said light in an image space of the optical component being measured,
• deducing the surface topography of said optical component from said measurements of the maps of wavefront slopes by application of at least one calculating procedure comprising:
• providing a result surface which is a simple starting surface S.sub.D,
• an iterative optimization process with ray tracing in the measuring system, comprising performing at least once:
• calculation of a value of a merit function representative of a departure between the result surface and a surface of the optical component being measured;
• minimizing the value of the merit function by varying said result surface, wherein said varying is expressed in form of at least one intermediate surface S.sub.I,
• said result surface, said simple starting surface S.sub.D and the at least one intermediate surface S.sub.I being represented by a linear combination of a family of orthogonal functions.

A method of measuring directly a refractive index distribution of an optical component in a measuring system comprising the steps of:

• illuminating said optical component with incident light having a known wavefront, said light having wavefront slopes;
• measuring, in a given plane, maps of wavefront slopes of said light, after transmission through said optical component,
• deducing the refractive index distribution of said optical component from said measurements of the maps of wavefront slopes by application of at least one calculating procedure comprising:
• providing a result refractive index distribution which is a simple starting refractive index distribution N.sub.D,
• an iterative optimization process with ray tracing in the measuring system, comprising performing at least once:
• calculation of a value of a merit function representative of a departure between the result refractive index distribution and a refractive index distribution of the optical component being measured;
• minimizing the value of the merit function by varying said result refractive index distribution, wherein said varying is expressed in form of at least one intermediate refractive index distribution N.sub.I.

A method of measuring directly a refractive index distribution of an optical component in a measuring system comprising the steps of:

• illuminating said optical component with incident light having a known wavefront, said light having wavefront slopes;
• measuring, in a given plane, maps of wavefront slopes of said light, after transmission through said optical component, by determining, using a deflectometric method, paths of a plurality of rays of said light in an image space of the optical component being measured,
• deducing the refractive index distribution of said optical component from said measurements of the maps of wavefront slopes by application of at least one calculating procedure comprising:
• providing a result refractive index distribution which is a simple starting refractive index distribution N.sub.D,
• an iterative optimization process with ray tracing in the measuring system, comprising performing at least once:
• calculation of a value of a merit function representative of a departure between the result refractive index distribution and a refractive index distribution of the optical component being measured;
• minimizing the value of the merit function by varying said result refractive index distribution, wherein said varying is expressed in form of at least one intermediate refractive index distribution N.sub.I, said result refractive index distribution, said simple starting refractive index distribution N.sub.D and the at least one intermediate refractive index distribution N.sub.I being represented by a linear combination of a family of orthogonal functions.

A method of measuring directly surface topography of an optical component in a measuring system, comprising the steps of:

• illuminating said optical component with incident light having a known wavefront, said light having wavefront slopes,
• measuring, in a given plane, maps of wavefront slopes of said light, after reflection at said optical component or transmission by said optical component,
• deducing the surface topography of said optical component from said measurements of maps of wavefront slopes by application of at least one calculating procedure for determining characteristics of the surface topography of the optical component to be analyzed in form of maps of its principal curvatures, and comprising:
• a step in which derivatives are calculated, in several directions, of maps of wavefront slopes of said light after reflection at said optical component or transmission by said optical component,
• a calculation step starting from said derivatives, for curvatures of the wavefront of light after reflection at said optical component or transmission by said optical component,
• a step for computing a map of the principal curvatures of the surface topography of the optical component to be measured, starting from the curvatures thus calculated, and knowing the wavefront of the light incident on the optical component.

A device for direct measurement of a geometrical or an optical structure of an optical component to be measured, comprising:

• means for illuminating the optical component to be measured with light having a known wavefront, said light having wavefront slopes;
• means for supporting the optical component to be measured,
• means for measuring, in a given plane, maps of wavefront slopes of said light after reflection off said optical component or transmission by said optical component, and
• calculating means receiving results out-putted by said measuring means and deducing the geometrical or optical structure of said optical component from said measurements of maps of wavefront slopes, using an iterative optimization process.