Canon Kabushiki Kaisha

Yumiko Osaki

Yasunori Furukawa

Yoshiki Maeda

The method includes: calculating positional and angular magnification distributions of rays reflected by a reference aspheric surface on a light-receiving sensor and on a sensor conjugate surface; measuring a first wavefront of a reference light on the sensor; and calculating a second wavefront of the reference light on the sensor based on a parameter of an optical system. The method includes: moving at least two movable elements for calibration such that a difference between rotationally symmetric components of the first and second wavefronts becomes small; measuring, after the calibration, a third wavefront of the reference light on the sensor; measuring, after the calibration, a fourth wavefront of the measurement light on the sensor; and calculating the profile of the measurement object aspheric surface by using the third and fourth wavefronts, the positional and angular magnification distributions, and the profile of the reference aspheric surface.

Aspheric surface measuring method, aspheric surface measuring apparatus, optical element producing apparatus and optical element

The method includes: measuring a first wavefront of a reference light on a sensor by using the sensor; calculating a second wavefront of the reference light on the sensor by using a parameter of an optical system; changing an optical system parameter in calculation such that a difference between rotationally symmetric components of the first and second wavefronts becomes smaller; calculating, by using the changed parameter, a magnification distribution of rays of the reference light between on the sensor and on a sensor conjugate surface; measuring a first ray angle distribution of the reference light by using the sensor, and measuring a second ray angle distribution of a measurement light by using the light-receiving sensor. The method calculates the profile of the measurement object aspheric surface by using the profile of the reference aspheric surface, the first and second ray angle distributions and the magnification distribution.

Provided is a measurement method or apparatus that can reduce the time for measuring the shape of an entire test surface. Each of a plurality of measurement ranges is set so that one measurement range overlaps a portion of at least another measurement range to form an overlap region, each measurement range being a portion of the test surface. Then, the shape of the test surface is measured at a first resolution in a first measurement range among the plurality of measurement ranges, and is measured at a second resolution in a second measurement range. Pieces of data of the shapes of the test surface in the plurality of measurement ranges are stitched together using the resulting measurement data to calculate the shape of the test surface.

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Utsunomiya, Japan

Yumiko Osaki