Optical sensor for large flow full semiconductor dust particle counter

Abstract

The invention discloses an optical sensor for a large-flow all-semiconductor new type dust particle counter. In the forward direction of the light beam emitted by the semiconductor laser light source, an aspheric mirror, an incident aperture, an exit aperture and an optical trap are arranged in sequence, perpendicular to the optical path. A spherical reflector, a bell-mouth-type blocking diaphragm, and a photodetector are arranged on the top, and the positions of the photosensitive area and the photosensitive surface of the photodetector are respectively located on both sides of the spherical center of the spherical reflector, and satisfy the object-image relationship of geometric optics. A high-power semiconductor laser light source is used, a photodiode is used as a photodetector, and a gain-adjustable preamplifier circuit is placed on the shell behind the photodetector. The invention improves the counting efficiency, increases the counting efficiency and particle size resolution of the instrument; the instrument has a long service life and good interchangeability between instruments; and the power consumption is low, the price is low, and the small volume is conducive to the miniaturization development of the whole machine.

Description

technical field [0001] The invention belongs to cleanliness detection equipment, in particular to an optical sensor for a full-semiconductor dust particle counter with miniaturization, large flow, high signal-to-noise ratio, high particle size resolution, and high counting efficiency. Background technique [0002] With the continuous improvement of people's requirements for air cleanliness, material purity and processing accuracy, the measurement technology of micro particles is particularly important. The dust particle counter is the main measuring instrument used in the light scattering counting method to measure the particle size distribution. The laser dust particle counter is based on the Mie scattering theory. The scattered light generated by a single particle in the illumination beam is the direct measurement object, and then the measuring instrument is used to distinguish the particle size of the particle to be measured according to the difference in the scattered l...

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Problems solved by technology

But the above-mentioned patent has the following disadvantages: although the photomultiplier tube used has a fast response speed, it is bulky, which is not conducive to the miniaturization of the optical sensor, making it difficult to miniaturize the whole machine; At the same time, the use of photomultiplier tubes requires high-voltage power supply and its own shot noise, which affects the optimization and improvement of the signal-to-noise ratio of the instrument; the low-power lasers used, due to the low-power laser signal amplitude in large flow environments It is easy to miss counting, the signal-to-noise ratio is low, and the counting efficiency is low; after the laser is focused on the photosensitive area, the illumination light is not fully utilized, and the counting efficiency is damaged

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