Abstract: A method of manufacturing an optical element includes testing the optical element by using an interferometer optics generating a beam of measuring light illuminating only a sub-aperture of the tested optical element. The interferometer optics comprises a hologram. Results of the sub-aperture measurement are stitched together to obtain a measuring result with respect to the full surface of the optical element. Further, a method of calibrating the interferometer optics includes performing an interferometric measurement using a calibrating optics having a hologram covering only a sub-aperture of the full cross section of the beam of measuring light generated by the interferometer optics and stitching together the sub-aperture measurements to obtain a result indicative for the full cross section of the interferometer optics.

Abstract: A method of processing an optical element having a spherical surface comprises providing a first interferometer apparatus having an interferometer optics with an aspherical lens for transforming a beam of a first spherical beam type into a beam of a second spherical beam type, arranging the optical element in a beam path of an incident beam provided by the interferometer optics, interferometrically taking a first measurement of the optical element, and determining first deviations of the spherical surface. The method further comprises arranging the aspherical lens in a beam path of a measuring beam provided by a beam source of a second interferometer apparatus, wherein the measuring beam is one of the first spherical type and the second spherical type, interferometrically taking a second measurement using the measuring beam, and determining second deviations of an aspherical surface of the aspherical lens.

Abstract: A method of manufacturing an optical element includes testing the optical element by using an interferometer optics generating a beam of measuring light illuminating only a sub-aperture of the tested optical element. The interferometer optics comprises a hologram. Results of the sub-aperture measurement are stitched together to obtain a measuring result with respect to the full surface of the optical element. Further, a method of calibrating the interferometer optics includes performing an interferometric measurement using a calibrating optics having a hologram covering only a sub-aperture of the full cross section of the beam of measuring light generated by the interferometer optics and stitching together the sub-aperture measurements to obtain a result indicative for the full cross section of the interferometer optics.

Abstract: A method for qualifying and/or manufacturing an optical surface includes: arranging a first substrate having a first surface and a second surface opposite the first surface in a beam path of a first incident beam with the first surface facing towards the first incident beam, and taking an interferometric measurement of the second surface; arranging the first substrate in the beam path of the first incident beam with the second surface facing towards the first incident beam, and taking an interferometric measurement of the second surface; arranging a third surface of a second substrate in a beam path of a second incident beam, and taking an interferometric measurement of the third surface; arranging the third surface of the second substrate and the first substrate in the beam path of the second incident beam, and taking an interferometric measurement of the third surface.

Abstract: An interferometer system comprises a reference surface, a support for an object providing an object surface, a radiation source for emitting radiation of an adjustable frequency onto the reference surface and the object surface, a position-sensitive radiation detector, a controller for adjusting a plurality of different frequencies of the radiation emitted by the radiation source, and an integrator for averaging the interference patterns superposed on the radiation detector at different frequencies. Moreover, there is provided a method for recording an interferogram, a method for providing an object with a target surface as well as a method for manufacturing an object with a target surface.

Abstract: An interferometer system comprises a reference surface, a support for an object providing an object surface, a radiation source for emitting radiation of an adjustable frequency onto the reference surface and the object surface, a position-sensitive radiation detector, a controller for adjusting a plurality of different frequencies of the radiation emitted by the radiation source, and an integrator for averaging the interference patterns superposed on the radiation detector at different frequencies. Moreover, there is provided a method for recording an interferogram, a method for providing an object with a target surface as well as a method for manufacturing an object with a target surface.

Abstract: Cover caps to protect the lens and eyepiece of a sighting telescope are resiliently connected by a pair of elastic bands. Each cap is provided with a pair of respective axially-oriented channels, each channel being larger at the end in proximity to the front of its respective cap, and the smaller end of each channel is proportioned to permit one end of one of the elastic bands to be threaded therethrough. Each end portion of each band is first threaded through a respective one of the channels, and then each end portion is folded over and secured to itself to form a thickened endpiece. Thereafter, each endpiece is retracted into its respective channel.