Abstract: A displacement measurement system of heterodyne grating interferometer, comprises a reading head, a measurement grating and an electronic signal processing component. Laser light emitted from the laser tube is collimated, passes through the first polarization spectroscope, and then emits two light beams with a vertical polarization direction and a vertical propagation direction; the two light beams pass through two acousto-optic modulators and respectively generate two first-order diffraction light beams with different frequencies, which are later divided into reference light and measurement light; two parallel reference light beams form a beat frequency electric signal with positive and negative first-order diffraction measurement light respectively after passing through a measurement signal photo-electric conversion unit; the beat frequency signals are transmitted to the electronic signal processing component for signal processing, thus the output of linear displacement in two directions is realized.

Abstract: A dual-frequency grating interferometer displacement measurement system, comprises a dual-frequency laser, an interferometer, a measurement grating and an electronic signal processing component. The measurement system realizes displacement measurement based on grating diffraction, optical Doppler effect and optical beat frequency theory. Dual-frequency laser light is emitted from the dual-frequency laser and split into reference light and measurement light via a polarization spectroscope. The measurement light is incident to the measurement grating to generate positive and negative first-order diffraction. The diffraction light and the reference light form a beat frequency signal containing displacement information about two directions at a photo-detection unit, and linear displacement output is realized after signal processing.

Abstract: A two-stage medium-pressure screw air compressor includes a primary screw compressor (21) and a secondary screw compressor (22) communicating with the gas-liquid separator (6) via the first gas-liquid inlet (61). A first oil outlet (63) is connected to a mid section of a gas-liquid separator (6). The oil is injected into the lubricating components of the compressor is the first oil outlet (63), a first filter (64). A secondary oil-water separator (9) is connected to the first oil outlet (63) of the gas-liquid separator (6), the second oil-water separator (6) has an upper separating tank (91) and a lower separating tank. The water and the impurities contained in the lubricating oil can be eliminated at a largest extent, so as to create essential condition thr ensuring the screw compressor to operate continuously, stably and safely and provide high operational reliability, safety and long service life.

Abstract: A two-stage medium-pressure screw air compressor comprises a primary screw compressor (21) and a secondary screw compressor (22) communicating with the gas-liquid separator (6) via the first gas-liquid inlet (61). A first oil outlet (63) is connected to a mid section of a gas-liquid separator (6). The oil is injected into the lubricating components of the compressor is the first oil outlet (63), a first filter (64). A secondary oil-water separator (9) is connected to the first oil outlet (63) of the gas-liquid separator (6), the second oil-water separator (6) has an upper separating tank (91) and a lower separating tank. The water and the impurities contained in the lubricating oil can be eliminated at a largest extent, so as to create essential condition thr ensuring the screw compressor to operate continuously, stably and safely and provide high operational reliability, safety and long service life.