Measurement sensor for inhalable dust concentration

Abstract

The invention discloses an inhalable dust concentration measuring sensor, comprising: a semiconductor laser light source. An aspherical mirror, an incidence diaphragm, an extinction diaphragm, a photosensitive area, a spherical reflecting mirror, an emergent diaphragm and a light trap are arranged in turn in the forward direction of the beam. The extinction diaphragm is of a long tube shape, and the opening of the diaphragm is close to the photosensitive area; the spherical reflecting mirror located at the right side of the extinction diaphragm ensures that the photosensitive area and the photosensitive surface of a photoelectric detector are respectively located at the two sides near the spherical center of the spherical reflecting mirror and the physical image relation in geometrical optics is met; the photoelectric detector is a high-sensitivity photoelectric diode; and the sampling nozzles in the gas path are distributed with respect to the photosensitive area. In the invention, the measurement is more accurate as the quality concentration of the inhalable dust is calculated by the energy sum of scattered lights in the particle swarm, and the measuring sensor has wide application as being free from the limit of the total particle number in a unit volume; the signal-to-noise ratio of the sensor is greatly improved as the light path is provided with three diaphragms; and the noise is low, and the measurement is more accurate and stable as the concentration measuring circuit adopts an integral method.

Description

technical field [0001] The invention relates to air cleanliness testing equipment, in particular to a sensor for measuring the concentration of inhalable dust. Background technique [0002] In the prior art, the technical solution adopted by the inhalable dust concentration measurement sensor, such as the utility model patent "laser dust measuring instrument optical probe" ( The patent number is 99251922.5), which adopts the scattered light collection optical path and the illumination optical path whose optical axes are perpendicular to each other. The intersection of the two optical axes is the center point of the photosensitive area. On the illumination optical path, it advances along the beam emitted by the semiconductor laser as the light source. In the direction, a collimator lens, a cylindrical lens whose focal point coincides with the center point of the photosensitive area, a photosensitive area and a light trap are arranged in sequence. On the light path for collec...

AI Technical Summary

Problems solved by technology

The main problems existing in the prior art are: 1. There is no diaphragm on the optical path, which inevitably leads to a decrease in the signal-to-noise ratio of the sensor

2. The use of particle counting to measure dust mass concentration itself has great limitations. It has certain requirements for the measurement object, that is, the number of particles per unit volume cannot exceed a certain value. It is generally used for the measurement of dust mass concentration in a relatively clean environment

When the concentration of dust particles in the measured environment increases, two or more particles appear in the photosensitive area of ​​the sensor at the same time, and the measurement will produce a huge error

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