Canon Kabushiki Kaisha

Ko Ishizuka

Shigeki Kato

Hidejiro Kadowaki

Yasushi Kaneda

Takayuki Kadoshima

Sakae Horyu

Satoshi Ishii

Hiroshi Kondo

Masahiko Igaki

Tetsuharu Nishimura

Masaaki Tsukiji

Ryo Sasaki

Masaru Nyui

Yoichi Kubota

Koichi Masegi

Makiko Ogasawara

There is provided an absolute encoder advantageous in accuracy of an output thereof against a defect in a scale thereof. In the absolute encoder, a detector detects a part of an array of marks of the scale, and outputs a data sequence corresponding to the part. A processor stores information indicating a correspondence between each of a plurality of code sequences and an absolute coordinate of motion of the scale, and outputs information of the absolute coordinate based on the data sequence and the information. The processor detects an error of the data sequence, and performs rewriting of the information based on the detected error.

Absolute encoder that provides increased accuracy against defect in scale thereof

A two-dimensional absolute encoder includes a scale having marks arranged thereon along first and second directions different from each other, a detector configured to perform first detection that detects rows of a first number of marks arranged in the first direction and second detection that detects rows of a second number of marks arranged in the second direction, and a processor configured to determine absolute positions of the scale in the first and second directions based on outputs from the detector. Each of the marks has one of different characteristic values each corresponding to a combination of a quantized first code for indicating a position in the first direction and a quantized second code for indicating a position in the second direction, the number of the different characteristic values being smaller than the number of the combinations.

Two-dimensional absolute encoder and scale with marks each having one of a plurality of different characteristic values

A two-dimensional absolute encoder includes; a scale on which marks are arranged at predetermined pitches along first and second directions; a detector configured to detect a number of marks arranged in each direction; and a processor configured to obtain an absolute position of the scale in the each direction based on outputs from the detector. Each mark has one of characteristic corresponding to information of a quantized code used for indicating a position in the each direction. The processor is configured to generate a code sequence including the number of codes based on detection of the number of marks and information corresponding to the characteristic, and to obtain an absolute position of the scale in the each direction based on the code sequence.

Two-dimensional absolute encoder and scale therefor

An interferometer measures a displacement of an object to be measured by observing a fluctuation in intensity of interfering light generated by dividing light emitted from a light source into two light beams and overlaying the two light beams. The interferometer includes: a light-receiving unit including a light-receiving area including a plurality of partial areas and configured to detect the interfering light in each of the plurality of partial areas; and a processing unit configured to calculate a value of an index indicating uniformity of a phase distribution of the interfering light in the light-receiving area by using a detection result in each of the partial areas.

Interferometer

An absolute rotary encoder comprises a scale having marks arranged at a first pitch; a first detector and a second detector including plural photoelectric conversion elements arranged at a second pitch smaller than the first pitch, and configured to detect a predetermined number of marks, the second detector disposed opposite to the first detector; and a computing device. The computing device is configured to generate a data string by quantizing a periodic signal output from the first detector, and obtains first angle data from the data string, to normalize amplitudes of the periodic signals output from the first and second detectors, to average the normalized periodic signal to obtain second angle data from a phase of the averaged periodic signal, and to combine the first and second angle data to generate data representing an absolute rotation angle.

Absolute rotary encoder

An absolute rotary encoder comprises: a rotary member which includes a cylindrical surface on which a plurality of marks are arranged at a predetermined pitch in a circumferential direction; a light source configured to emit a light toward the cylindrical surface; a detector configured to detect a predetermined number of marks of the plurality of marks; and a computing device configured to obtain an absolute rotation angle of the rotary member based on an output from the detector. The detector is configured to output a signal corresponding to the predetermined number of marks and having an uneven period resulting from a geometrical layout of the light source, the cylindrical surface, and the detector. The computing device is configured to correct the signal using correction data so as to reduce unevenness of the period, and to obtain the absolute rotation angle of the rotary member using the corrected signal.

The laminated diffractive optical element includes plural diffraction gratings (and) laminated with each other, the respective diffraction gratings being formed of a same light-transmissive material. In the element, reflective films are formed on grating surfaces (and) of the respective diffraction gratings, each of the reflective films being disposed between the diffraction gratings. Each of the reflective films reflects light in a specific wavelength range and transmits light in a wavelength range different from the specific wavelength range, the specific wavelength ranges of the respective reflective films being different from each other. The grating surfaces of the respective diffraction gratings are formed in shapes different from each other according to the specific wavelength ranges corresponding to the respective reflective films.

Encoder and interferometer that generate M-phase signals by multiplying N-phase signals by M coefficient sets, where N is not less than 6 and M is not smaller than 2

A wavelength shift measuring apparatus of the present invention is a wavelength shift detection sensor (WLCD) which measures a shift of a wavelength of a light beam emitted from a light source, and includes a beam splitter (BS) splitting the light beam emitted from the light source into a plurality of light beams and to synthesize two light beams among the plurality of light beams to generate an interference light, a spacer member (SP) provided so that an optical path length difference of the two light beams split by the beam splitter (PBS) is constant, and a plurality of photoelectric sensors (PD) detecting the interference light generated by the beam splitter (BS). The plurality of photoelectric sensors (PD) output a plurality of interference signals having phases shifted from one another based on the interference light to calculate a wavelength shift using the plurality of interference signals.

Wavelength shift measuring apparatus, optical source apparatus, interference measuring apparatus, exposure apparatus, and device manufacturing method

A displacement measurement apparatus includes a first diffraction grating transmitting light from a light source and producing diffracted beams including first to third diffracted beams output in different directions; a second diffraction grating movable together with an object to be measured, provided in a plane parallel to the first diffraction grating, and reflecting the first to third diffracted beams transmitted through the first diffraction grating; a first photodetector receiving the first and second diffracted beams diffracted by the second diffraction grating; a second photodetector receiving at least the third diffracted beam transmitted through the first diffraction grating; and a calculation unit calculating displacement of the object in a first direction in accordance with the beams received by the first photodetector, and displacement of the object in a second direction, different from the first direction, in accordance with the beam received by the second photodetector.

Displacement measurement apparatus

An apparatus includes a light source, a scale which is configured to have first and second diffraction grating portions which differ from each other in a grating pitch, a light receiving portion configured to receive first and second interference light fluxes generated from interference of a plurality of diffraction light fluxes, at the first and second diffraction grating portions, respectively, a light flux emitted from the light source and have different orders of diffraction, and to output first and second periodic signals based on an intensity of the first and second interference light fluxes, respectively, and a computing unit configured to output, based on the first and second periodic signals a signal representing an origin of displacement of the scale.

Origin detection apparatus, displacement measurement apparatus and optical apparatus

A first beam having high coherence and a second beam having low coherence and having a central wavelength difference from that of the first beam are multiplexed onto the same optical axis. First and second multiplexed beams obtained by beam splitting are emitted at a measurement reflection plane and a reference plane, respectively. The reflected first and second multiplexed beams are multiplexed and interfere with each other. The interference generates a first interference signal that is obtained from the first beams at the interference unit and that relates to information on the distance to the measurement reflection plane and a second interference signal that is obtained from the second beams. The first and second interference signals are used to carry out calculations for determining the position of a measurement origin for the measurement reflection plane.

Absolute position measurement apparatus

A first beam having high coherence and a second beam having low coherence are multiplexed onto the same optical axis. This multiplexed beam is split into first and second multiplexed beams. The first multiplexed beam is directed towards a measurement reflection plane of an object to be measured, and the second multiplexed beam is directed towards a reference plane. The first and second multiplexed beams that are reflected from the measurement reflection plane and the reference plane, respectively, are multiplexed to cause the first beams to interfere with each other and the second beams to interfere with each other. Calculations are carried out to determine a measurement origin on the basis of the first and second interference signals obtained from the first and second beams, respectively.

Position detection apparatus comprises: an incident unit that forms a parallel beam from a light beam of a light source and supplies the parallel beam to a beam splitter in a way that the separated beams, obtained from the parallel beam by the beam splitter, are respectively incident upon the reference surface and the measurement target surface at an angle; and a reflection unit that reflects the separated beams, which have been reflected by the reference surface and the measurement target surface and integrated to a light path by the beam splitter, to be supplied to the beam splitter as a parallel beam along the light path, and generates a signal corresponding to a phase difference of the separated beams by interfering a light beam that has been supplied from the reflection unit, separated by the beam splitter, reflected by the reference surface and the measurement target surface, and integrated again to a light path by the beam splitter.

Position detection apparatus and method

Interference measuring apparatus having an optical system for dividing a coherent light beam into two light beams, and causing the divided two light beams to pass along discrete optical paths. The light beams are made into linearly polarized light beams orthogonal to each other and given modulation to the phase of the wave front of at least one of them. The wave fronts of the linearly polarized light beams are superposed one upon the others. A light dividing member divides the light beams superposed one upon the other by the optical system into a plurality of light beams. A polarizing plate takes out each light beam with a 45&#xb0; polarized component, and a plurality of light receiving elements individually receive the light beams taken out by the polarizing plate.

Interference measuring apparatus for detecting a plurality of stable phase difference signals

A grating interference type optical encoder has a scale board, a diffraction grating located on the scale board, a light receiving element, an illumination optical system for emitting a coherent light fluxes to the diffraction grating on the scale board that relatively moves, to produce two diffraction light fluxes having different orders, an arc-shaped grating for re-emitting to the diffraction grating the two diffraction light fluxes having the different orders which are produced in the diffraction grating portion through a deflection unit, and a light guiding unit for superimposing rediffraction light fluxes produced by rediffracting the diffraction light fluxes re-emitted to the diffraction grating and guiding the superimposed rediffraction light fluxes to the light receiving element. The grating interference type optical encoder further includes: a phase grating that divides the rediffraction light fluxes superimposed between the diffraction grating and the light receiving element into a plurality of light fluxes, and a linear deflection element having different deflection directions corresponding to the plurality of light fluxes divided by the phase grating.

Growing community of inventors

Saitama, Japan

Ko Ishizuka