Particle counter sensor light beam homogenizing and sharpening illumination system

Abstract

The invention discloses a particle counter sensor light beam homogenizing and sharpening illumination system. The system comprises a semiconductor laser, and a first aspheric mirror, a micro lens array scattering sheet, a second aspheric mirror, a circular hole diaphragm, a cylindrical mirror and a rectangular hole diaphragm are sequentially arranged in the light beam emitting direction of the semiconductor laser; an air inlet nozzle and an air outlet nozzle are arranged perpendicular to the light beam emitting direction, sampling airflow flows in from the air inlet nozzle of the sensor cavityand flows out from the air outlet nozzle, and a photosensitive area is formed in the intersection and overlapping area of the sampling airflow and light beams. According to the optical illumination system, the light beams are sharpened and homogenized, so that the light beams in the photosensitive area are uniformly distributed and narrowed, and the optical background noise in a scattered light collection cavity is reduced through the combined diaphragms, so that the optical illumination system has the characteristics of small size, easiness in adjustment, high particle size measurement accuracy, high resolution, high signal-to-noise ratio and high sensitivity.

Description

technical field [0001] The invention belongs to the field of proximity detection equipment, in particular to an illumination system for homogenizing and sharpening beams of particle counter sensors. Background technique [0002] The clean room environment is widely used in semiconductor, electronics, biomedical engineering, precision machining and other industries. The concentration of particulate matter in the environment has a key impact on product quality. The optical particle counter is an important instrument for measuring the particle size and particle number concentration of particles in clean ambient air. Its measurement principle is based on the Mie scattering theory. Related to the particle size, the measurement and counting of the particle size can be realized by collecting scattered light and converting it into an electrical signal through a photodetector. The research on domestic particle counters is decades later than that of foreign countries, so the performa...

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Problems solved by technology

However, the above-mentioned patents have the following disadvantages: Although the photodiode is used to replace the photomultiplier tube to reduce the volume, the length of the single aspheric lens system is still long, which is not conducive to the miniaturization of the sensor. Since the output laser beam of the high-power semiconductor laser is multi-mode, it passes through the lens. After converging, the wavefront intensity distribution of the beam in the photosensitive area is uneven, and the spot size of the airflow passing through is wide, resulting in a decrease in particle size resolution and an increase in measurement error, and the instability of the laser output optical power will also cause particle size measurement. Accuracy is biased

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