Abstract: An optical encoder includes a sensor head, an encoder scale, and an optical wavefront dividing element. The sensor head includes a substrate, a light source, a first optical detector, and a second optical detector. The light source, the first optical detector, and the second optical detector are disposed on the substrate. The scale includes a first track and a second track. The optical wavefront dividing element is disposed between the sensor head and the scale. A light beam emitted by the light source is divided into a first beam and a second beam by the wavefront dividing element. The first beam is incident on the first track and the second beam is incident on the second track. Light from the first beam diffracted by the first track is incident on the first optical detector. Light from the second beam diffracted by the second track is incident on the second optical detector.

Abstract: The disclosed electronic processing apparatus calculates and applies calibrations to sensors that produce quasi-sinusoidal, quadrature signals. The apparatus includes either or both of fixed and programmable electronic circuits. The apparatus includes a circuit to calculate the phase and magnitude corresponding to the two input (quadrature) signals. The apparatus also includes a circuit for accumulating the number of cycles of the input signals. The apparatus also includes a circuit to generate Gain, Offset, and Phase calibration coefficients, wherein the circuit compares the phase space position of the measured phasor with the position of an idealized phasor, the locus of the idealized phasor in phase space being a circle of predetermined radius with no offset. The calculation of the coefficients occurs without user intervention, according to a pre-programmed rule or rules.

Abstract: A position sensor having a wavefront compensator, a detector array and a grating in a diffractive configuration, and which incorporates a second wavefront compensator and a second detector array in parallel with the first wavefront compensator and detector array, to provide a second optical channel for measurement of an additional degree of freedom (roll), the effects of which can then be removed from or utilized in the main measurement channel; and in which the relative effects of grating roll and grating displacement are different in this second channel when compared to the first sensing channel; and in one embodiment of which this differentiation is created by having different ratios of the grating period to the detector fringe period in the two channels.

Abstract: The disclosed optical encoder includes a scale and a sensor head. The scale includes an optical grating and an optical element. The sensor head includes a light source, a detector array, and an index detector all of which are disposed on a substrate. The scale is disposed opposite the sensor head and is disposed for movement relative to the sensor head. The distance between the scale and the sensor head is selected so that the detector array lies near a talbot imaging plane. The light source emits a diverging beam of light, which is directed towards the scale. Light from the diverging beam of light is diffracted by the grating towards the detector array. Light from the diverging beam of light is diffracted by the optical element towards the index detector. The detector array provides a measurement of the position of the sensor head relative to the scale. The index detector provides a reference measurement of the position of the sensor head relative to the scale.