An optical rotary encoder includes a code disk, a laser source unit, a focusing unit and a photodetector array. The focusing unit converts the laser beam emitted by the laser source unit into incident laser beams that have a plurality of light points respectively on code tracks of the code disk, such that the code disk modulates the incident laser beams to form optical code signals. The photodetector array receives and converts the optical code signals into electric code signals.

A position-measuring device and a corresponding method for measuring an absolute position includes a material measure having a first binary code and a second binary code and a sensor device that scans the first and second binary codes. The sensor device scans the first binary code, which has a first number of code words, each having the same code word length. The second binary code of the material measure forms a portion of the first binary code and has a second number of the code words that can be mapped onto the first binary code.

A coordinate measuring machine including a surface plate; a probe moving body; an INC pattern and ABS pattern along a moving direction of the probe moving body; an INC detector that outputs a plurality of waveform signals in accordance with the moving amount based on the INC pattern; an ABS detector that outputs an absolute position signal of the probe moving body based on the ABS pattern in response to a request signal; and a control device that has a INC counting portion that counts the waveform signals outputted by the INC detector; a position information obtaining portion that reads a counted value at a timing when a work is detected by a probe; and a presetting portion that emits the request signal to the ABS detector to obtain the absolute position signal, and presets the counting portion to this absolute position signal.

In this optical rotary encoder, detection tracks of a rotating disc are irradiated with detection light emitted from a light-emitting element. An optical signal obtained via slits in the detection tracks passes through a slit pattern in a fixed slit plate and is received by light-receiving surfaces of a light-receiving element. The slit pattern in the fixed slit plate is formed so as to fit into a range of an effective spot of the detection light. An LED or other light-emitting element that has a small effective spot diameter can be used, which is advantageous in terms of reducing costs and making the device more compact.

A detection method includes obtaining first count data and second count data during rotation of an encoder disc mounted at and configured to rotate together with a rotation object and determining a rotation parameter of the rotation object according to the first count data and the second count data. The encoder disc includes N detection target portions arranged along a circumferential direction of the encoder disc. The N detection target portions include N−K first detection target portions and K second detection target portions. Along the circumferential direction of the encoder disc, a width of one of the N−K first detection target portions is different from a width of one of the K second detection target portions. The first count data is obtained when one detection target portion of the N detection target portions is detected. The second count data is recorded between two neighboring detection target portions.

An optical encoder is provided. The encoder includes an optical disc mounted on a shaft, the optical disc containing pit and land markings; an optical pickup unit for an optical disc that receives light from the optical disc and supplies as an output an electrical signal representative of the received light, comprising: a reading head objective lens, and dynamic steering actuators that control the focus and tracking of the reading head objective lens; a processor that receives as an input the electrical signal from the optical pickup unit and reports motion of the substrate based on the received at least one electrical signal.

There is provided an interpolation circuit of an optical encoder including a phase shifter circuit, two multiplexers, two digital circuits and four comparators. The phase shifter circuit receives signals sequentially have a 90 degrees phase shift and outputs multiple phase shifted signals. Each of the two multiplexers receives a half of the multiple phase shifted signals and outputs two pairs of phase shifted signals, each pair having 180 degrees phase difference, respectively to two comparators connected thereto. Each of the two digital circuits controls the corresponding multiplexer to select the two pairs of phase shifted signals from the half of the multiple phase shifted signals.

A method is provided for spatially modulating electromagnetic radiation at high frequency where the modulation is phase, polarization or direction of propagation comprises a substrate carrying an ordered array of optical elements in relative motion with respect to an incident beam of electromagnetic radiation to be modulated and measuring the relative motion. The array contains at least three optical elements and at least two different types of optical elements. At least some of the optical elements are formed from and integral to the substrate material. The optical elements may be fabricated on the substrate material by a subtractive process. The electromagnetic radiation to be modulated is incident on a region of the substrate termed the active region. As the substrate moves relative to the incident electromagnetic radiation, the active region also moves and the designation of individual optical elements changes also.

A method of operating a position encoder apparatus, including a scale having features defining position information and a readhead for reading the scale. The method includes: calculating extrapolated position information from at least one previous reading of the scale; comparing an extrapolated position with a position calculated from a reading of the scale to determine any discrepancy between them; using the extrapolated position information whether or not there is a discrepancy; and maintaining a record of any discrepancies.

A rotary-linear actuation assembly comprising a casing internally housing an output shaft arranged coaxial with an actuation axis (A) in a translationally and rotationally movable manner, at least two actuators, of which a first actuator is adapted to impose a translational movement along the actuation axis (A) on the output shaft and a second actuator is adapted to impose a rotary movement about the actuation axis (A) on the output shaft, and at least one position sensor adapted to detect an instant position of the output shaft inside the casing. At least one position sensor is mounted in fixed manner in respect of rotation about the actuation axis (A) and in fixed manner in respect of translation along the actuation axis (A) and faces at least a portion of the output shaft.