Abstract: Optical assembly comprising a variable focal length lens assembly comprising a variable focal length lens and an actuating unit, wherein an energy absorption rate of energy absorbed by the variable focal length lens assembly depends on the applied controlling signal. The optical assembly comprises a controlling unit configured to control focal length settings of the variable focal length lens by providing respective controlling signals and to apply a default controlling signal for providing a default focal length and default energy absorption rate. The controlling unit provides a thermal stabilisation functionality, the thermal stabilisation functionality is defined by applying a varying controlling signal related to a varying focal length and applying a compensation controlling signal related to a compensating focal length.

Abstract: A method for measurement of a surface, in particular according to the principle of Optical Coherence Tomography, whereby distances to points of the surface are measured based on interferograms and classifying of measurements as non-valid or valid based on evaluation of phase change or amplitude change of a respective interferogram.

Abstract: A machine state monitoring system for recurrently determining a change in static or dynamic properties of a geometry of a machine with positional encoders to derive a coordinate information of at least a first machine portion with respect to a second machine portion, which are movable with respect to one another. The monitoring system includes one calibration-monitoring-unit with an optical, at least two-dimensional measuring location sensing unit which is fixed to the first machine portion and configured to optically sense an at least two dimensional location information of an artifact which is provided at the second machine portion, and temporarily moved into a sensing range for determining the change in the static or dynamic properties of the geometry of the machine by a comparison of multiple of such sensings, the compensation parameters are then updated and is used to derive the coordinate information from the encoders.

Abstract: A method for measurement of a surface, in particular according to the principle of Optical Coherence Tomography, whereby distances to points of the surface are measured based on interferograms and classifying of measurements as non-valid or valid based on evaluation of phase change or amplitude change of a respective interferogram.

Abstract: A machine state monitoring system for recurrently determining a change in static or dynamic properties of a geometry of a machine with positional encoders to derive a coordinate information of at least a first machine portion with respect to a second machine portion, which are movable with respect to one another. The monitoring system includes one calibration-monitoring-unit with an optical, at least two-dimensional measuring location sensing unit which is fixed to the first machine portion and configured to optically sense an at least two dimensional location information of an artifact which is provided at the second machine portion, and temporarily moved into a sensing range for determining the change in the static or dynamic properties of the geometry of the machine by a comparison of multiple of such sensings, the compensation parameters are then updated and is used to derive the coordinate information from the encoders.

Abstract: Some embodiments of the invention relate to a method for measuring an angle between two spatially separated elements having the steps: preparing a multiplex hologram having a plurality of interference patterns, at least two having different angles of incidence of an object light wave onto a hologram plane; arranging the multiplex hologram in a first element plane on a first element; lighting the multiplex hologram with a reference light wave; arranging a light detector in a second element plane on a second element; detecting a reference light wave refracted on an interference pattern with a light detector; creating an intensity pattern from the detected refracted reference light wave; assigning the angle of incidence stored as machine readable data to the intensity pattern; and/or calculating an angle between the first element plane and the second element plane from the assigned angle of incidence.

Abstract: Some embodiments of the invention relate to a coordinate measuring method for detecting an object surface by means of a coordinate measuring machine, comprising a measuring head for accommodating a sensor, a guiding unit for producing a relative movement of the measuring head in relation to the object surface in at least one direction, an optical sensor for detecting the object surface, and a control unit, the object surface being optically detected by the optical sensor during the coordinate measuring method, and a data set representing a surface profile in an object profile domain being generated. The data set is filtered by simulating contact of the surface profile represented by the data set with a virtual tactile sensor, and a tactile data set is derived from the simulated contact such that the tactile data set represents a virtual tactile surface profile in a virtual sensor domain.

Abstract: Method and systems for determining a change of distance to an object by interferometry with emitting measurement laser light from a laser diode are disclosed. The method may include receiving at least a part of the measurement laser light, superimposing the reflected measurement laser light with a reference laser light and thereby providing at an interferometric phase and determining the change of distance to the object depending on the superimposition. In some embodiments, the measurement laser light may be emitted with low coherence and broad spectral bandwidth. An emitting wavelength of the measurement laser light may be fluctuating hop-freely within the spectral bandwidth causing interferometric phase fluctuations.

Abstract: Some embodiments of the invention relate to a coordinate measuring method for detecting an object surface by means of a coordinate measuring machine, comprising a measuring head for accommodating a sensor, a guiding unit for producing a relative movement of the measuring head in relation to the object surface in at least one direction, an optical sensor for detecting the object surface, and a control unit, the object surface being optically detected by the optical sensor during the coordinate measuring method, and a data set representing a surface profile in an object profile domain being generated. The data set is filtered by simulating contact of the surface profile represented by the data set with a virtual tactile sensor, and a tactile data set is derived from the simulated contact such that the tactile data set represents a virtual tactile surface profile in a virtual sensor domain.

Abstract: Some embodiments of the invention relate to a method for measuring an angle between two spatially separated elements having the steps: preparing a multiplex hologram having a plurality of interference patterns, at least two having different angles of incidence of an object light wave onto a hologram plane; arranging the multiplex hologram in a first element plane on a first element; lighting the multiplex hologram with a reference light wave; arranging a light detector in a second element plane on a second element; detecting a reference light wave refracted on an interference pattern with a light detector; creating an intensity pattern from the detected refracted reference light wave; assigning the angle of incidence stored as machine readable data to the intensity pattern; and/or calculating an angle between the first element plane and the second element plane from the assigned angle of incidence.

Abstract: Method and systems for determining a change of distance to an object by interferometry with emitting measurement laser light from a laser diode are disclosed. The method may include receiving at least a part of the measurement laser light, superimposing the reflected measurement laser light with a reference laser light and thereby providing at an interferometric phase and determining the change of distance to the object depending on the superimposition. In some embodiments, the measurement laser light may be emitted with low coherence and broad spectral bandwidth. An emitting wavelength of the measurement laser light may be fluctuating hop-freely within the spectral bandwidth causing interferometric phase fluctuations.

Abstract: An apparatus for reading from or writing to a near-field optical recording medium capable of detecting tilt and spherical aberration is described. The apparatus comprises a light source for generating a reading light beam, a near-field lens, an aberration compensation element, and a diffractive optical element. The diffractive optical element is switchable between a far-field mode and a near-field mode and is adapted to generate a main light beam and four or more sub-beams from the reading light beam for determining at least a cover layer thickness error signal. For this purpose it has an outer region with a first grating period and an inner region having a diameter smaller than an effective numerical aperture of the near-field lens, which in the near-field mode has a second grating period and which has a switchable inner area having a diameter smaller than a far-field numerical aperture of the near-field lens, which in the far-field mode has the first grating period.

Abstract: Methods for operating an apparatus for reading from or writing to a Super-RENS optical recording medium, an apparatus for reading from Super-RENS optical recording media using such methods, and a Super-RENS optical recording medium suitable for such methods are described. The super-RENS optical recording medium has location information that is readable without super-RENS effect. The location information is provided as low-frequency information. For locating a position on the super-RENS optical recording medium, a reading light beam with a power below a power necessary for achieving a super-RENS effect is generated and the location information is retrieved from the super-RENS optical recording medium.

Abstract: The optical storage medium comprises a substrate layer and a data layer disposed on the substrate layer, the data layer having a mark/space data structure being arranged in tracks, wherein on a first track, the marks are enlarged in length and the spaces are shortened in length, and on an adjacent track, the marks are shortened in length and the spaces are enlarged in length. The track pitch between adjacent tracks is particularly below a diffraction limit of ?/2*NA of a pickup for reading of the data.

Abstract: A method and an apparatus for reading from a near-field optical recording medium are described. The apparatus includes: an optical system for generating a signal beam and a reference beam; a near-field lens for illuminating the signal beam onto the near-field optical recording medium, for collimating a reflected signal beam, and for reflecting the reference beam; and at least a first detector and a second detector for obtaining a homodyne detection signal from the reflected signal beam and the reflected reference beam.

Abstract: An apparatus for reading from or writing to a near-field optical recording medium capable of detecting tilt and spherical aberration is described. The apparatus comprises a light source for generating a reading light beam, a near-field lens, an aberration compensation element, and a diffractive optical element. The diffractive optical element is switchable between a far-field mode and a near-field mode and is adapted to generate a main light beam and four or more sub-beams from the reading light beam for determining at least a cover layer thickness error signal. For this purpose it has an outer region with a first grating period and an inner region having a diameter smaller than an effective numerical aperture of the near-field lens, which in the near-field mode has a second grating period and which has a switchable inner area having a diameter smaller than a far-field numerical aperture of the near-field lens, which in the far-field mode has the first grating period.

Abstract: A method and an apparatus for reading from a near-field optical recording medium are described. The apparatus includes: an optical system for generating a signal beam and a reference beam; a near-field lens for illuminating the signal beam onto the near-field optical recording medium, for collimating a reflected signal beam, and for reflecting the reference beam; and at least a first detector and a second detector for obtaining a homodyne detection signal from the reflected signal beam and the reflected reference beam.

Abstract: A holographic storage system having an improved data page quality is described. The holographic storage system includes a special optical filter or a special light source for emphasizing the high frequency components of a reference beam and/or an object beam. This is achieved by an optical filter arranged in a Fourier plane, which has a higher attenuation at the center than at the edge. Alternatively, an adapted light source for generating the reference beam and/or the object beam is arranged in a Fourier plane. The light beam emitted by the light source has a higher intensity close to the edge than at the center.

Abstract: The present invention relates to a holographic storage system, and more specifically to a method for pixel detection in a coaxial holographic storage system. In a holographic storage system according to the invention, with a coaxial arrangement of an object beam and a reference beam the bright pixels within the object beam have a phase shift of essentially ? relative to the reference beam. For readout of a data page contained in a reconstructed object beam a detector detects an interference pattern generated by the interference between the reference beam and the reconstructed object beam.

Abstract: The optical storage medium comprises a substrate layer and a data layer disposed on the substrate layer, the data layer having a mark/space data structure being arranged in tracks, wherein on a first track, the marks are enlarged in length and the spaces are shortened in length, and on an adjacent track, the marks are shortened in length and the spaces are enlarged in length. The track pitch between adjacent tracks is particularly below a diffraction limit of ?/2*NA of a pickup for reading of the data.