A method for analyzing distribution of tolerances on a freeform surface in an optical system. Establishes a freeform surface imaging optical system. A plurality of fields is selected, and maximum and minimum margins of wavefront errors in each field are defined. One freeform surface in one field is selected, an isolated point jumping model is established, and an isolated point is placed in different areas of the freeform surface of the one field. A local figure error with extreme values corresponding to each field is resolved, based on the maximum and minimum margins of wavefront errors, and the local surface tolerance distributions of the freeform surface in the plurality of fields are integrated together.

An optical inspection device includes: a wafer support unit configured to support a wafer in which a plurality of Fabry-Perot interference filter portions are formed, each of the plurality of filter portions in which a distance between the first mirror portion and the second mirror portion facing each other varies by an electrostatic force, the wafer support unit configured to support the wafer such that a direction in which the first mirror portion and the second mirror portion face each other follows along a reference line; a light emission unit configured to emit light to be incident on each of the plurality of filter portions along the reference line; and a light detection unit configured to detect light transmitted through each of the plurality of filter portions along the reference line. The wafer support unit has a light passage region that allows light to pass along the reference line.

A system (100) and method can monitor a reflectance of a mirror target that includes at least one curved mirror (M). The system (100) can take a first irradiance measurement of the sun (S), the first irradiance measurement representing a direct solar irradiance. The system (100) can take a second irradiance measurement that represents an irradiance from a reflection of the sun (S) from the mirror target plus background irradiance from a reflection of the sky from the mirror target. The system (100) can take a third irradiance measurement that represents the background irradiance from the reflection of the sky from the mirror target. The system (100) can determine a reflectance of the mirror target from the first, second, and third irradiance measurements. The system (100) can compare the reflectance to a specified reflectance threshold, and, upon determining that the reflectance of the mirror target is less than the specified reflectance threshold, can generate an alert signal.

A measurement apparatus (10) for interferometrically determining a surface shape of a test object (14). A radiation source provides an input wave (42), a multiply-encoded diffractive optical element (60), which is configured to produce by diffraction from the input wave a test wave (66) that is directed at the test object and has a wavefront in the form of a free-form surface and at least one calibration wave (70), and a capture device (46). The calibration wave has a wavefront with a non-rotationally symmetric shape (68f), wherein cross sections through the wavefront of the calibration wave along cross-sectional surfaces each aligned transversely to one another have a curved shape. The curved shapes in the different cross-sectional surfaces differ in terms of an opening parameter. The capture device (46) captures a calibration interferogram formed by superimposing a reference wave (40) with the calibration wave after interaction with a calibration object (74).

Provided is a device for designed for use with a telescope having a primary mirror, such as a reflecting telescope, and to accurately analyzing the size of a step between paired regions of a plurality of mirror segments of the primary mirror. The device designed for use with a telescope whose primary mirror is composed of a plurality of mirror segments, and to analyze the size of a step between paired regions of the plurality of mirror segments comprises: a mask disposed in an optical axis of the primary mirror orthogonally to the optical axis at a given position where a plurality of mirror segment images as respective projected images of the plurality of mirror segments do not overlap each other, wherein a plurality of pairs of primary slits is formed at respective positions in the mirror segment images, wherein each of the primary slits are adjacent to a boundary between the paired regions of the mirror segment images and opposed and parallel to each other with a given spacing therebetween, and wherein at least one reference slit is arranged with respect to each of pairs of the primary slits in the mask, such that it extends at a given angle which is not parallel to each of the pairs of primary slits.

An apparatus for capturing at least partially reflective surfaces includes a detection surface assembly, an illumination device configured to emit an illumination pattern toward the at least partially reflective surface so as so project, by reflection via the at least partially reflective surface, a first reflection pattern and a second reflection pattern onto the detection surface assembly. The apparatus includes a capturing unit configured to capture the first reflection pattern and the second reflection pattern from the detection surface assembly.

A method and apparatus for characterizing the surface form of an optical element, in particular a mirror or a lens element of a microlithographic projection exposure apparatus, includes: carrying out a plurality of interferometric measurements, in each of which an interferogram is recorded between a test wave emanating from a portion of the optical element in each case and a reference wave, the position of the optical element relative to the test wave being altered between these measurements, and calculating the figure of the optical element on the basis of these measurements. This calculation is carried out iteratively such that, in a plurality of iteration steps, the figure of the optical element is ascertained in each case by carrying out a forward calculation, each of these iteration steps being based in each case on a reference wave that was adapted based on the preceding iteration step.

The invention relates to a coolable optical table with a table top and at least three table legs. Securing means for securing objects such as optical elements are provided in a table surface of the table top. The table legs are equipped with a damping device for damping vibrations.

The present invention relates to a device for measuring an optical element comprising: a. a light source, b. a measurement structure which illuminated by the light of the light source and has areas of different transmissivity, c. an optical imaging system for converting light transmitted by the measurement structure into a collimated measuring beam which is directed onto the optical element, and d. a sensor for detecting a reflection of the measuring beam generated on the optical element for detecting a transmission of the measuring beam passing through the optical element. According to the invention the light source has a plurality of light segments, wherein the device further comprises a control unit which is designed for independently controlling the plurality of light segments. The invention further relates to a corresponding method for measuring an optical element. The device according to the invention and the method according to the invention can be used particularly flexibly due to the segmented light source.

A particle detection device includes: a first light source to emit first irradiation light; a first light-collection member; a second light-collection member facing the first reflection surface; a second light source to emit second irradiation light; and a first light-reception element. When the first light source emits the first irradiation light, the first light-reception element detects, as the first incident light, scattered light generated when a particle existing at a detection position in a target space is irradiated with the first irradiation light. When the second light source emits the second irradiation light, the first light-reception element detects, as the first incident light, a light ray of the second irradiation light that is reflected by the first reflection surface and a light ray of the second irradiation light that is reflected by both the first reflection surface and the second reflection surface.