CN107941154A

CN107941154A - A kind of displacement measurement system and measuring method

Info

Publication number: CN107941154A
Application number: CN201710984847.1A
Authority: CN
Inventors: 侯昌伦; 辛青; 臧月
Original assignee: Hangzhou Electronic Science and Technology University
Current assignee: Hangzhou Taoyi Data Technology Co.,Ltd.
Priority date: 2017-10-20
Filing date: 2017-10-20
Publication date: 2018-04-20
Anticipated expiration: 2037-10-20
Also published as: CN107941154B

Abstract

The invention discloses a kind of displacement measurement system, it is characterised in that the system comprises：Light source；Alvarez lens groups, the Alvarez lens groups are made of the first Alvarez lens and the 2nd Alvarez lens of the complementation of face shape, and the 2nd Alvarez lens are moved relative to the first Alvarez lens along perpendicular to optical axis direction, the Alvarez lens groups focal length is adjusted by adjusting displacement distance, and then controls the light energy of the directional light arrival pin hole；Pin hole, for projecting converging light through the Alvarez lens groups；Optical detector, for detecting the light energy passed through from the pin hole.Simple in measurement system structure provided by the invention, only several device junction closing lights, which are gained knowledge, can be achieved with the high-acruracy survey of displacement, and measurement accuracy is up to 1.33nm.For this application for high precision displacement sensory field, tool has very important significance.

Description

A kind of displacement measurement system and measuring method

Technical field

The invention belongs to displacement measurement field, and in particular to a kind of displacement measurement system and measuring method.

Background technology

In the prior art, measuring the mode of displacement has very much, generally use displacement sensing when accurately measuring micro-displacement Device.Displacement sensor is also applied to the measurement of the geometric senses such as the displacement of object, thickness, vibration, distance, diameter, in civilian and army Had a wide range of applications with field.

Alvarez lens be by Alvarez propose a kind of polynomial surface face shape lens, by one group of two panels so Lens can produce focal length variations along perpendicular to the relative motion of optical axis direction.

In the prior art, displacement sensor is broadly divided into inductive displacement transducer, capacitive displacement transducer, photo-electric Displacement sensor, ultrasonic type displacement sensor, Hall displacement transducer.

The content of the invention

In view of above-mentioned, the present invention proposes a kind of displacement measurement system and measuring method, which can be high-precision Ground measures displacement.

The first embodiment of the present invention provides a kind of displacement measurement system, including：

Light source；

Alvarez lens groups, the Alvarez lens groups by the complementation of face shape the first Alvarez lens and second Alvarez lens form, and the 2nd Alvarez lens relative to the first Alvarez lens along perpendicular to optical axis side To movement, the Alvarez lens groups focal length is adjusted by adjusting displacement distance, and then control the directional light to reach pin hole Light energy；

Pin hole, for the converging light projected through the Alvarez lens groups；

Detector, for detecting the light energy passed through from the pin hole.

The operation principle of measuring system that embodiment of the present invention provides is：

Alvarez lens surface polynomial equations are：

Producing focal length f is：

Wherein, f is two Alvarez lens combination focal lengths, and A is multinomial coefficient, and 2 δ are between two Alvarez lens Movement distance, n be Alvarez lens Refractive Index of Material；

When two Alvarez lens are having a small displacement perpendicular to optical axis direction, combined focal length can be caused to produce Raw big change, from formula (2)：

When two Alvarez lens produce the distance change of Δ δ, cause combined focal length to produce the change of Δ f, originally gather The burnt spot size in pin hole position is changed into：

Wherein r is the size of the spot radius in the situation of change lower pinhole plane of focal length, and D is saturating to be radiated at Alvarez Beam size on mirror；

It can be obtained by formula (3) and (4)：

Assuming that the radius of pin hole is r₀, and the Energy distribution of hot spot is uniform, due to the change of focal length, what pin hole received Energy μ is changed into：

It can be seen from formula (6) Alvarez lens position produce change, cause through pin hole energy production very Sensitive change.The displacement of Alvarez lens can be accurately measured by the energy detected through pin hole.

Preferably, be equipped with collimation lens between the light source and the Alvarez lens groups, for by the light source The transmitting light of transmitting projects after becoming directional light.

Preferably, the light source is laser, LED etc..

Preferably, the optical detector could alternatively be light power meter.

Second embodiment of the invention provides a kind of method of the systematic survey displacement provided using first embodiment, Comprise the following steps：

After the 2nd Alvarez lens are fixed in measurand, the light source, collimation lens, the first Alvarez Lens, the 2nd Alvarez lens, pin hole and optical detector are sequentially arranged along optical axis direction；

The opposite position of the first Alvarez lens and the 2nd Alvarez lens is calculated according to the light energy through pin hole Move, which is the displacement of measurand.

Simple in measurement system structure provided by the invention, only several device junction closing lights, which are gained knowledge, can be achieved with the high-precision of displacement Degree measurement, measurement accuracy is up to 1.33nm.For this application for high precision displacement sensory field, there is critically important meaning Justice.

Brief description of the drawings

Fig. 1 is the structure diagram for the displacement measurement system that embodiment provides；

Fig. 2 is the structure diagram for the displacement measurement system with collimation lens that embodiment provides；

Fig. 3, Fig. 4 are the schematic diagrams that the movement of Alvarez lens produces power variation in embodiment.

Embodiment

In order to more specifically describe the present invention, below in conjunction with the accompanying drawings and embodiment is to technical scheme It is described in detail.

Embodiment

Fig. 1 is the structure diagram for the displacement measurement system that embodiment provides.Referring to Fig. 1, displacement provided in this embodiment Measuring system includes light source 101；The Alvarez lens groups being arranged in light source emergent light light path, Alvarez lens groups are by face shape Complementary the first Alvarez lens 102 and the 2nd Alvarez lens 103 form, and the 2nd Alvarez lens 103 are relative to the One Alvarez lens 102 are moved along perpendicular to optical axis direction, and Alvarez lens group focal lengths are adjusted by adjusting displacement distance, into And 101 emergent lights of light source are controlled to reach the light energy of pin hole；Pin hole 104, is assembled for being projected through Alvarez lens groups Light；Optical detector 105 is used to detect the light energy passed through from the pin hole.

In the present embodiment, light source 101 is laser and LED etc..

Fig. 3, Fig. 4 give the schematic diagram that the movement of Alvarez lens produces power variation., can be with from Fig. 3 and Fig. 4 It is clearly not available：When the 2nd Alvarez lens 103 relative to the first Alvarez lens 102 along being moved perpendicular to optical axis direction, When producing micro-displacement, the focal length of whole Alvarez lens groups can produce change, become f Δ f by original f, hot spot is by original A point become radius be r hot spot.

As shown in Fig. 2, collimation lens 106 is also equipped with the present embodiment between Alvarez lens grant light source 101, this Become directional light after the collimated lens 106 of diverging light that sample light source 101 is emitted to be mapped on Alvarez lens rent.

In this example, it is assumed that the multinomial coefficient A of the first Alvarez lens 102 and the 2nd Alvarez lens 103 =1.0E-2 (1/mm2), the material of lens is PMMA (refractive index n is 1.5), and clear aperture D is 10mm, the radius r of pin hole₀For 2um.Assuming that the distance of pin hole plane to Alvarez lens is 20mm；When focus is located just at pin hole plane, the energy of all light Amount can all pass through, at this moment the 2nd Alvarez lens 103 relative to 102 displacement distance δ of the first Alvarez lens= 2.5mm.When δ change 1um when (the 2nd Alvarez lens 103 relative to the first Alvarez lens 102 move 1um away from From), i.e. during Δ δ=1um, it can be obtained by formula (5)：

In pin hole plane, the radius r of hot spot is：

Assuming that the energy of hot spot is uniformly distributed in pin hole plane, the energy that pin hole can must be passed through by formula (6) is light beam Energy (focus is just at pin hole plan-position through the energy of pin hole)：

Assuming that detector can accurately measure 1/1000 variable quantity of beam energy, then it is saturating to calculate Alvarez The precision of mirror displacement distance measurement can reach：

Therefore, the measurement accuracy of 1.33nm can be reached, can realize nano level accurate measurement.

In the present embodiment, above displacement test system is applied in measurement displacement, measuring method is：

After 2nd Alvarez lens 103 are fixed in measurand, light source 101, collimation lens 106, first Alvarez lens 102, the 2nd Alvarez lens 103, pin hole 104 and optical detector 105 are sequentially arranged along optical axis direction；

First Alvarez lens 102 and the 2nd Alvarez lens 103 are calculated according to the light energy through pin hole 104 Relative displacement, the displacement be measurand displacement.

Technical scheme and beneficial effect is described in detail in above-described embodiment, Ying Li Solution is the foregoing is merely presently most preferred embodiment of the invention, is not intended to limit the invention, all principle models in the present invention Interior done any modification, supplementary, and equivalent replacement etc. are enclosed, should all be included in the protection scope of the present invention.

Claims

A kind of 1. displacement measurement system, it is characterised in that the system comprises：

Light source；

Alvarez lens groups, the Alvarez lens groups are saturating by the first Alvarez lens of face shape complementation and the 2nd Alvarez Microscope group into, and the 2nd Alvarez lens relative to the first Alvarez lens along moving perpendicular to optical axis direction, lead to Cross adjustment displacement distance and adjust the Alvarez lens groups focal length, and then control the emergent light of the light source to reach the light of pin hole Energy；

Pin hole, for projecting converging light through the Alvarez lens groups；

Optical detector, for detecting the light energy passed through from the pin hole.
2. displacement measurement system as claimed in claim 1, it is characterised in that in the light source and the Alvarez lens groups Between be equipped with collimation lens, the transmitting light for the light source to be launched projects after becoming directional light.
3. displacement measurement system as claimed in claim 1, it is characterised in that the light source is laser, LED.
4. displacement measurement system as claimed in claim 1, it is characterised in that the optical detector replaces with light power meter.
5. a kind of method using any systematic survey displacement of claims 1 to 33, comprises the following steps：

After the 2nd Alvarez lens are fixed in measurand, the light source, collimation lens, the first Alvarez are saturating Mirror, the 2nd Alvarez lens, pin hole and optical detector are sequentially arranged along optical axis direction；

The relative displacement of the first Alvarez lens and the 2nd Alvarez lens is calculated according to the light energy through pin hole, should Displacement is the displacement of measurand.