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

An aspheric surface measuring apparatus configured to measure profile of a measurement object aspheric surface, the apparatus comprising:

• a light-receiving sensor;
• an illumination optical system configured to project light from a light source as an illumination light that is a spherical wave onto the measurement object aspheric surface;
• and
• an imaging optical system configured to introduce a reflected light that is the light reflected by the measurement object aspheric surface to the light-receiving sensor,
• wherein the apparatus is configured to:
• provide, to a wavefront of the illumination light, a curvature that brings an absolute value of an angle of the reflected light to a smaller value than a maximum value of absolute values of angles of peripheral rays on a side closer to the measurement object aspheric surface than the imaging optical system;
• locate an exit pupil of the imaging optical system when defining the light-receiving sensor as an object surface at a position where the absolute value of the angle of the reflected light is smaller than the maximum value;
• and
• provide, to a sensor conjugate surface having a conjugate relationship with the light-receiving sensor provided by the optical system, a curvature and a position that cause rays of the reflected light not to intersect with one another on the sensor conjugate surface,
• wherein all of the sensor conjugate surface, the wavefront of the illumination light and the measurement object aspheric surface are set to have a same one of convex and concave surfaces toward a same side in an optical axis direction of the illumination and imaging optical systems.

An optical element producing apparatus comprising:

• a shaping apparatus configured to shape an optical element;
• and
• a measuring apparatus configured to measure profile of a measurement object aspheric surface of the optical element by an aspheric surface measuring method using output from a light-receiving sensor, by projecting light from a light source as an illumination light that is a spherical wave onto the measurement object aspheric surface through an illumination optical system and introducing a reflected light that is the light reflected by the measurement object aspheric surface to the light-receiving sensor through an imaging optical system, the method comprising:
• providing, to a wavefront of the illumination light, a curvature that brings an absolute value of an angle of the reflected light to a smaller value than a maximum value of absolute values of angles of peripheral rays on a side closer to the measurement object aspheric surface than the imaging optical system;
• locating an exit pupil of the imaging optical system when defining the light-receiving sensor as an object surface at a position where the absolute value of the angle of the reflected light is smaller than the maximum value;
• providing, to a sensor conjugate surface having a conjugate relationship with the light-receiving sensor provided by the optical system, a curvature and a position that cause rays of the reflected light not to intersect with one another on the sensor conjugate surface;
• and
• setting all of the sensor conjugate surface, the wavefront of the illumination light and the measurement object aspheric surface to have a same one of convex and concave surfaces toward a same side in an optical axis direction of the illumination and imaging optical systems.