CN2109569U - Optical probe for laser dust particle counter - Google Patents

Optical probe for laser dust particle counter Download PDF

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Publication number
CN2109569U
CN2109569U CN 92215120 CN92215120U CN2109569U CN 2109569 U CN2109569 U CN 2109569U CN 92215120 CN92215120 CN 92215120 CN 92215120 U CN92215120 U CN 92215120U CN 2109569 U CN2109569 U CN 2109569U
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CN
China
Prior art keywords
reflector
collecting light
laser
ellipsoidal
light ellipsoidal
Prior art date
Application number
CN 92215120
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Chinese (zh)
Inventor
黄惠杰
邹海兴
Original Assignee
中国科学院上海光学精密机械研究所
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Application filed by 中国科学院上海光学精密机械研究所 filed Critical 中国科学院上海光学精密机械研究所
Priority to CN 92215120 priority Critical patent/CN2109569U/en
Publication of CN2109569U publication Critical patent/CN2109569U/en

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Abstract

The utility model relates to a novel optical probe for a laser dust particle counter, which is used for detecting the cleanliness of clean environment and is mainly composed of a He-Ne laser, a polarization beam expander, an aperture diaphragm, a light collecting ellipsoid reflector, a diaphragm for eliminating stray light, a backward flat reflector, a collecting lens, a field diaphragm and an optoelectronic receiver. The utility model has the characteristics of big scope of grain diameter dynamic measurement, high reliability of measurement results, simple and compact structure, reasonable arrangement, small volume, high measuring speed, etc.; the measuring speed of the utility model for measuring a sampling point of ten-stage clean environment is more than ninety times of that of the prior art.

Description

The utility model is the detecting instrument of clean environment cleanliness factor---a kind of novel optical probe of laser dust particle counter.
The optic probe of Japan KC-14 type laser dust particle counter is made of He-Ne laser tube 1, Brewster window 2, collecting light ellipsoidal surface reflector 3, sampling air flow passage 4, light sensitive area 5, laserresonator catoptron 6, end window photomultiplier 7, as shown in Figure 1.This optic probe adopts half external cavity laser, and light sensitive area is positioned at laserresonator.Its main performance is as follows:
1. the minimum particle diameter of surveying: 0.11 μ m;
2. particle diameter dynamic detecting range: 0.11~0.5 μ m;
3. light sensitive area (being the air-flow xsect) size: the circle of φ 0.18mm, for the 1/2(lasing beam diameter of laser beam radius is 0.72mm);
4. scattered light is collected solid angle: 2.05 π Srad;
5. sampling flow: 300ml/min;
There is following shortcoming in this optic probe:
Detection time long, inefficiency.Eucalyptus is according to the requirement of u.s. federal standard 209D, when using this optic probe that class 100 clean environment is detected, need with the detection that just can finish a sampled point in 19 minutes, and, then need with the detection that just can finish a sampled point in more than 3 hours for 10 grades of clean environments.Thereby the requirement from increasing work efficiency, the practicality of this probe has been subjected to considerable restraint.
Detection time and sampling flow are inversely proportional to, and sampling flow is directly proportional with the light sensitive area size.The light sensitive area of this optic probe is positioned at laserresonator, because can't take measures extensible beam, so it is size-constrained in the diameter of endovenous laser bundle.According to the illumination uniformity requirement, the normal light sensitizing range is on perpendicular to beam direction, and its width can only be 1/4 of lasing beam diameter.
2. the particle diameter dynamic detecting range is little.Laser beam in the laserresonator has standing wave effect, thereby has the period profile of λ/2 along the light intensity of optical axis direction.So when detecting particle diameter less than the small-particle of this Cycle Length, measuring error is big, because the particle of same particle size will produce different scatter light flux when the diverse location by light sensitive area.Therefore, the lower limit of particle diameter dynamic detecting range is the standing wave effect decision, is limited to about 0.1 μ m under this usually.
The upper limit of particle diameter dynamic detecting range is by the decision of the gain characteristic of laserresonator.The loss that causes by light beam when particle is during greater than the gain of laserresonator, and laser instrument extinguishes.Particle is big more, and the loss that causes is big more, thus this just to have limited the particle diameter higher limit be 2.0 μ m.Though the particle about 2.0 μ m can not cause that laser instrument extinguishes,, the measurement result of this moment is very unreliable.
In order to overcome the deficiency of above-mentioned optic probe, the utility model provides a kind of novel optical probe for laser dust particle calculator with fast, characteristics such as dynamic detecting range is wide, compact conformation detection time.To satisfy the requirement that modern industry detects clean environment.
Structure of the present utility model is: a He-Ne laser instrument, along putting a collecting light ellipsoidal surface reflector on its laser beam direction of propagation with optical channel and sample gas passage; Between laser instrument and collecting light ellipsoidal surface reflector, one polarization beam expander is arranged, between polarization beam expander and collecting light ellipsoidal surface reflector, an aperture diaphragm is arranged near the collecting light ellipsoidal surface reflector place near the laser instrument place; Laser beam is passed the optical channel directive backward plane reflector of collecting light ellipsoidal surface reflector, and a diaphragm for eliminating stray light is arranged between collecting light ellipsoidal surface reflector and backward plane reflector; Sampling air flow passage on the collecting light ellipsoidal surface reflector is: by the interior focus of collecting light ellipsoidal surface reflector, and it is vertical mutually in twos with the optical axis three of the direction of propagation of laser and collecting light ellipsoidal surface reflector, and the three intersects at the interior focus of collecting light ellipsoidal surface reflector, and light sensitive area is focus place in this just also; Outer focus at collecting light ellipsoidal surface reflector has been located a photelectric receiver after a while, between photelectric receiver and collecting light ellipsoidal surface reflector, disposes a field stop in the outer focus of collecting light ellipsoidal surface reflector; One collector lens is arranged between collecting light ellipsoidal surface reflector and field stop.Shown in Fig. 2,3.
Polarization beam expander in the utility model is made of the identical single shaft wafer of two block size materials, as shown in Figure 4.The optical axis of crystal and wafer surface normal angle at 45.The principal section of two wafers is vertical mutually, and promptly second wafer turns over 90 ° of angles with respect to first wafer.The angle at 45, principal section of the polarization direction of incident ray polarization single-mode laser beam and first wafer, incident light is divided into two-beam by first wafer, i.e. ordinary light O and non-ordinary light E.In second wafer, the O light in first wafer becomes E light, and vice versa.Each wafer in the two plates produces the transversal displacement amount that equates between two light.Thickness is that the total displacement amount that the polarization beam expander of 2t produces between emergent ray EO and OE is:
d= |n 2 e-n 2 o|t/(n 2 e+n 2 o
In the formula, n eAnd n oBe respectively the refractive index of E and O light.The transversal displacement direction of two light beams is perpendicular to the sampling air flow passage in the utility model.
Vertical mutually from the EO of polarization beam expander outgoing with the direction of vibration of OE two light beams, so they are superimposed with the intensity addition form.Like this, can obtain a stack district with two light beams is the light sensitive area of the even illumination at center.Calculating shows that when illumination uniformity was not less than 88%, on perpendicular to the laser beam optical axis direction, the width of light sensitive area was 1.7W, and W is the radius of incoming laser beam here.
The crystalline material of polarization beam expander can be the positive uniaxial crystal quartz, also can be the uniaxial negative crystal kalzit.
The xsect of the sampling air flow passage on the collecting light ellipsoidal surface reflector is Long Circle or rectangle, and its length direction and the laser beam direction of propagation coincide.This is because the light intensity uniformity on the laser beam optical axis direction is fabulous.The sampling air flow passage of this form has enlarged light sensitive area greatly.
The reflecting surface of backward plane reflector is the high reflection of multilayer, and reflectivity is greater than 99.9%.
The course of work of the present utility model: the linear polarization single-mode beams of laser instrument output is behind polarization beam expander and aperture diaphragm, the left side optical channel that passes collecting light ellipsoidal surface reflector enters light sensitive area, again by being returned by the backward plane reflector reflection again behind the optical channel of the right, repeatedly come back reflective between two catoptrons, when flowing through light sensitive area with the direction perpendicular to laser beam, dust particle to be measured produces light scattering, particle scattering light in certain solid angle is after the collecting light ellipsoidal surface reflector reflection, outer focus with ellipsoid is a convergent point directive collector lens, and the light of assembling once more through collector lens projects on the photelectric receiver by the field stop that is positioned at collector lens image planes place.The electric signal of photelectric receiver output provides measurement result after being handled by electronic system thereafter.
Above-mentioned aperture diaphragm, the clear aperature of diaphragm for eliminating stray light and field stop is preferably square.
Advantage of the present utility model:
1. light sensitive area is positioned at outside the laserresonator, has avoided the influence of sampling air flow to laser generation, has enlarged the particle diameter range of dynamic measurement, has improved the reliability of measurement result;
2. adopt the polarization beam expander that laser beam is expanded bundle, increased light sensitive area size and this regional light intensity uniformity greatly;
3. adopt the sampling air flow passage of Long Circle or rectangular cross section, made full use of luminous energy, greatly increased the light sensitive area size again simultaneously, thereby accelerated measuring speed widely.
4. between backward plane reflector and laser instrument outgoing mirror, laser beam is repeatedly shone tested dust particle back and forth, thereby has increased substantially light sensitive area illumination light intensity, makes system can survey littler dust particle;
5. add collector lens and make scattered light effectively collect the increase of solid angle scope, dwindled the volume of system simultaneously, make that the total system compact conformation is simple;
6. behind the adding collector lens, its photelectric receiver also can utilize side-on photomultiplier except that utilizing the end window photomultiplier, thus the further structure of simplified system;
7. reasonably arrange the position of aperture diaphragm, diaphragm for eliminating stray light and field stop, reasonably do not count the light hole shape of these diaphragms, greatly reduce the noise of system, improved the performance of system.
Description of drawings:
Fig. 1 is the structural representation of prior art Japan KV-14 type optical probe for laser dust particle calculator.
Fig. 2 is the vertical view cutaway drawing of laser dust particle counter novel optical sonde configuration of the present utility model, and Fig. 3 is that laser dust particle counter novel optical of the present utility model is visited the vertical profile elevation cross-sectional view of closing structure.
Fig. 4 is to be the index path of the polarization beam expander made with positive uniaxial crystal, the optical axis direction of the double-head arrow among the figure " ← → " expression wafer.
Embodiment:
Fig. 2 and Fig. 3 are the structural drawing of most preferred embodiment of the present utility model.He-Ne laser instrument 1 is the output of linear polarization single mode, and pipe range is 500mm, and output power is 5mW, and the laser beam radius is 0.4mm; Polarization beam expander 8 usefulness kalzits are made, and the thickness of two wafers is 3.27mm; Two focal lengths of collecting light ellipsoidal surface reflector 3 are respectively 15mm, and it is 2.2 π Srad that scattered light is effectively collected the solid angle scope; Light sensitive area 5 be shaped as Long Circle, its length is 2mm, width is 0.65mm, area is 1.21mm 2Collector lens the 1, the 2nd, focal length equals the plano-convex lens of 98.1mm; Photelectric receiver 14 adopts end window photomultiplier.The clear aperature of aperture diaphragm 9, diaphragm for eliminating stray light 10 and field stop 13 is square, and backward plane reflector 11 reflectivity are greater than 99.9%.
It is 0.065 μ m that the minimum of embodiment is surveyed particle diameter, and maximum sample gas flow is 28.31/min, and the particle diameter dynamic detecting range is 0.065 μ m~10.0 μ m.The native system detection speed is fast, and is stable and reliable for performance, simple and compact for structure, easy to adjust.Only with the detection that can finish a sampled point in the class 100 clean environment 12 seconds, and with the detection that can finish a sampled point in 10 grades of clean environments in 2 minutes, than Japanese KC-14 type for 10 grades of clean environments fast more than 90 times with the detection time that just can finish a sampled point in more than 3 hours.

Claims (4)

1, a kind of laser dust particle counter novel optical probe, it is characterized in that on direction of beam propagation, being equipped with a collecting light ellipsoidal surface reflector with optical channel and sampling air flow passage along a He-Ne laser instrument, between collecting light ellipsoidal surface reflector and laser instrument, one polarization beam expander is arranged near the laser instrument place, between polarization beam expander and collecting light ellipsoidal surface reflector, one aperture diaphragm is arranged near the collecting light ellipsoidal surface reflector place, laser beam is passed directive one backward plane reflector behind the collecting light ellipsoidal surface reflector, a diaphragm for eliminating stray light is arranged between backward plane reflector and collecting light ellipsoidal surface reflector, focus has been located a photelectric receiver after a while outside collecting light ellipsoidal surface reflector, between collecting light ellipsoidal surface reflector and photelectric receiver, there is a field stop at the focus place outside collecting light ellipsoidal surface reflector, and a collector lens is arranged between field stop and collecting light ellipsoidal surface reflector.
2, a kind of laser dust particle counter novel optical probe according to claim 1, it is characterized in that sampling air flow passage on the collecting light ellipsoidal surface reflector is an interior focus by collecting light ellipsoidal surface reflector and vertical mutually in twos with the optical axis three of the direction of propagation of laser beam and collecting light ellipsoidal surface reflector, and the three mutually Jiao in the interior focus place of collecting light ellipsoidal surface reflector.
3, according to claim 1 one sharp laser dust particle counter novel optical probe is characterized in that the polarization beam expander is that, principal section orthogonal single shaft wafer identical by two equal and opposite in directions, material constituted.
4, a kind of laser dust particle counter novel optical probe according to claim 1 and 2 is characterized in that its xsect of sampling air flow passage on the collecting light ellipsoidal surface reflector is Long Circle or rectangle, and its length direction and laser propagation direction coincide.
CN 92215120 1992-01-30 1992-01-30 Optical probe for laser dust particle counter CN2109569U (en)

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Application Number Priority Date Filing Date Title
CN 92215120 CN2109569U (en) 1992-01-30 1992-01-30 Optical probe for laser dust particle counter

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Application Number Priority Date Filing Date Title
CN 92215120 CN2109569U (en) 1992-01-30 1992-01-30 Optical probe for laser dust particle counter

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102331394A (en) * 2010-07-12 2012-01-25 苏州工业园区鸿基洁净科技有限公司 Photoelectric sensor of high flow airborne particle counter
CN102519850A (en) * 2011-11-07 2012-06-27 南通大学 Optical sensor capable of detecting granularity and shape feature of particles in real time
CN102564928A (en) * 2012-01-09 2012-07-11 南通大学 Sensor for optical particle counters
CN103149136A (en) * 2013-03-08 2013-06-12 苏州市尚科产品检测中心 Sensor cavity
CN105115880A (en) * 2015-09-14 2015-12-02 宁波中物东方光电技术有限公司 High-precision light-electric dust particle detection device and detection method
CN109596488A (en) * 2018-11-29 2019-04-09 海拉(厦门)电气有限公司 A kind of novel laser PM2.5 dust sensor
CN112630127A (en) * 2021-03-10 2021-04-09 中国科学院上海高等研究院 Vacuum particle counter

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102331394A (en) * 2010-07-12 2012-01-25 苏州工业园区鸿基洁净科技有限公司 Photoelectric sensor of high flow airborne particle counter
CN102331394B (en) * 2010-07-12 2014-04-16 苏州工业园区鸿基洁净科技有限公司 Photoelectric sensor of high flow airborne particle counter
CN102519850A (en) * 2011-11-07 2012-06-27 南通大学 Optical sensor capable of detecting granularity and shape feature of particles in real time
CN102564928A (en) * 2012-01-09 2012-07-11 南通大学 Sensor for optical particle counters
CN102564928B (en) * 2012-01-09 2013-03-27 南通大学 Sensor for optical particle counters
CN103149136A (en) * 2013-03-08 2013-06-12 苏州市尚科产品检测中心 Sensor cavity
CN105115880A (en) * 2015-09-14 2015-12-02 宁波中物东方光电技术有限公司 High-precision light-electric dust particle detection device and detection method
CN109596488A (en) * 2018-11-29 2019-04-09 海拉(厦门)电气有限公司 A kind of novel laser PM2.5 dust sensor
CN112630127A (en) * 2021-03-10 2021-04-09 中国科学院上海高等研究院 Vacuum particle counter

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