A heterodyne one-dimensional grating measuring device and measuring method thereof, including a light source, a reading head, a photoelectric receiving module, and a signal processing system. The light source is configured to generate two linearly polarized lights having characteristics of overlapping, polarization orthogonal, and fixed frequency difference. The reading head is configured to receive two beams of polarized lights and be respectively incident on a surface of a moving measuring grating to generate a +1-order diffracted light and a −1-order diffracted light. The photoelectric receiving module is configured to receive the +1-order diffracted light and the −1-order diffracted light to form two paths of beat frequency signals. The signal processing system is configured to perform differential calculation on the two paths of the beat frequency signals to realize a displacement measurement of single diffraction of the measuring grating for four-fold optical subdivision.

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.

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 scale includes: a substrate that is made of low expansion glass of which a thermal expansion coefficient is 1×10.sup.−7/K or less; and scale gratings having a plurality of gratings that are arranged on a first face of the substrate at a predetermined interval and are made of a transparent inorganic material of which a thermal expansion coefficient is more than 1×10.sup.−7/K.

A scale includes: a substrate that is made of low expansion glass of which a thermal expansion coefficient is 1×10.sup.−7/K or less; and scale gratings having a plurality of gratings that are arranged on a first face of the substrate at a predetermined interval and are made of a transparent inorganic material of which a thermal expansion coefficient is more than 1×10.sup.−7/K.

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.

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.

An optical displacement sensor includes: a splitting unit that splits the light radiated from the light source into a first light ray and a second light ray; a reflection unit including a first reflection part and a second reflection part provided at a predetermined angle with respect to the first reflection part; and a fold-back reflection unit that folds-back and reflects the light that has gone through the reflection unit to the reflection unit. The optical displacement sensor is characterized in that the reflection unit reflects the first light ray and the second light ray that are split by the splitting unit and have gone through the diffraction unit from the first reflection part to the second reflection part, and reflects the first light ray and the second light ray that are reflected by the fold-back reflection unit from the second reflection part to the first reflection part.

A cantilever linear motion reference device employing two-layer air suspension. By means of a two-layer force sealed air suspension structure, the invention realizes two-dimensional air suspension support and motion guiding and improves the rotational stiffness per unit for an air suspension working surface. By combining accurate driving and feedback control, the invention achieves high speed, high acceleration, high frequency motion, and enables construction of a small-volume, long cantilever, high torque load two-dimensional motion reference device.

A cantilever linear motion reference device employing two-layer air suspension. By means of a two-layer force sealed air suspension structure, the invention realizes two-dimensional air suspension support and motion guiding and improves the rotational stiffness per unit for an air suspension working surface. By combining accurate driving and feedback control, the invention achieves high speed, high acceleration, high frequency motion, and enables construction of a small-volume, long cantilever, high torque load two-dimensional motion reference device.