CN109141252B

CN109141252B - An Optical Lever Measurement System Based on Parallel Plates

Info

Publication number: CN109141252B
Application number: CN201811042965.1A
Authority: CN
Inventors: 李杏华; 吕泽奎; 苏智琨
Original assignee: Tianjin University
Current assignee: Tianjin University
Priority date: 2018-09-06
Filing date: 2018-09-06
Publication date: 2020-04-14
Anticipated expiration: 2038-09-06
Also published as: CN109141252A

Abstract

The invention relates to an optical lever measurement system based on a parallel plate, comprising a laser, an optical lever, a ruler, a bracket and an object to be measured. The laser is a line laser, the laser is fixed on the bracket, and the laser emits The light is horizontal light; the light lever is provided with a first toe below one end, and the first toe is in contact with the object to be measured; the other end of the light lever is provided with a second toe and a third toe, which are in contact with the object to be measured. The upper part of the light lever is fixed with a parallel plate, the light lever is perpendicular to the parallel plate, the second toe and the third toe and the first toe are symmetrically distributed in a "T" shape device, and the second toe and the third toe are placed On a fixed platform; when the optical lever is in a horizontal state, the outgoing light of the in-line laser is perpendicular to the parallel plate; the scale plane of the scale is perpendicular to the outgoing light of the in-line laser. The system of the invention is simple and easy to build, convenient and quick to operate, and has high measurement accuracy.

Description

Optical lever measurement system based on parallel flat plate

Technical Field

The invention belongs to the technical field of measurement, and particularly relates to an optical lever measurement system based on a parallel flat plate.

Background

The optical lever is a commonly used optical amplifying device with tiny displacement and angle. Chinese patent 2896220Y discloses an optical lever device of small length of laser survey, and the device major structure is "T" shape support, and the laser instrument is installed to the support top, and the support below is 3 toe that become "T" word and distribute, and the device can measure small angle, simple structure, convenient operation. However, the laser is mounted on the support, so that the load of the support is increased, the laser is not easily adjusted, and certain influence is caused on measurement. Chinese patent 104865135a measures young's modulus of a metal wire by using a common optical lever, that is, a form of placing a reflector on the optical lever, and this method achieves a measurement effect with a large visibility by magnifying light reflected by the optical lever on a scale, but this device has a high requirement on the scale, and the higher the magnification, the longer the scale, the length of the scale limits the magnification of the experimental device. There is therefore a need for an improved design of a light lever device.

Disclosure of Invention

The invention aims to provide an optical lever measuring system based on a parallel flat plate, which amplifies physical quantities such as micro displacement, micro angle and the like by utilizing the optical characteristics of the parallel flat plate, and has the advantages of simple and easy construction, convenient and quick operation and higher measuring precision. The technical scheme is as follows:

the utility model provides an optical lever measurement system based on parallel flat board, includes laser instrument, optical lever, scale, support and the object of awaiting measuring, its characterized in that:

the laser is a linear laser, the linear laser is fixed on the bracket, and the emergent light of the linear laser is horizontal light;

a first toe is arranged below one end of the optical lever and is in contact with an object to be detected; a second toe and a third toe are arranged below the other end of the optical lever, a parallel flat plate is fixed on the upper part of the optical lever, the optical lever is vertical to the parallel flat plate, the second toe and the third toe are symmetrically distributed in a T-shaped device shape, and the second toe and the third toe are placed on the fixed platform; when the optical lever is in a horizontal state, the emergent ray of the linear laser is vertical to the parallel flat plate;

the scale plane of the scale is perpendicular to the emergent light of the linear laser.

Preferably, the optical lever measuring system is characterized in that the height of the bracket can be adjusted.

The invention has the advantages and positive effects that: the plane reflector in the common light lever is replaced by a parallel flat plate, so that the amplifying nature of the light-changing lever is avoided, the middle measuring process is shortened, and the error of the system is reduced; the micro-displacement and micro-angle detection tool can measure physical quantities such as micro-displacement and micro-angle, has the advantages of high detection speed, high precision, simplicity in operation and low production cost, and can be used as a micro-physical quantity detection tool in the fields of mechanical manufacturing, electronic processing and the like.

Drawings

FIG. 1 is a schematic illustration of an application of the present invention;

FIG. 2 is a schematic diagram of the optical characteristics of a parallel plate used in the present invention;

FIG. 3 is a schematic view of the present invention in a measurement state.

In the figure: 1-laser, 2-parallel flat plate, 3-scale, 4-optical lever, 4-1-optical lever first toe, 4-2-optical lever second toe, 4-3-optical lever third toe, 5-object to be measured, 6, 7, 8-bracket

Detailed Description

In order to further understand the contents, features and effects of the present invention, the following embodiments are illustrated and described in detail with reference to the accompanying drawings:

as shown in fig. 1, an optical lever measurement system based on a parallel flat plate includes a laser, a parallel flat plate optical lever, a scale, a bracket, and an object to be measured, and is characterized in that:

the laser 1 is a linear laser, the line width is less than 1mm, the laser 1 is horizontally fixed on a support 8, the height of the support can be adjusted, and the emergent ray of the laser is a horizontal ray;

the parallel flat plate optical lever comprises an optical lever 4 and a parallel flat plate 2, a first toe 4-1 is arranged below one end of the optical lever 4 and is in contact with an object 5 to be measured, a second toe 4-2 and a third toe 4-3 are arranged below the other end of the optical lever, the second toe 4-2 and the third toe 4-3 are symmetrically distributed at two base angles of the parallel flat plate 2 and are distributed in a T-shaped device shape with the first toe, and the second toe 4-2 and the third toe 4-3 are placed on a fixed platform at the upper end of a support 7; the parallel flat plate 2 is vertically fixed right above a second toe 4-2 and a third toe 4-3 of the optical lever 4, the vertical section of the parallel flat plate 2 is vertical to the emergent light of the laser 1, the centers of the parallel flat plate and the emergent light are collinear, and the front and back inclination angles of the parallel flat plate can be adjusted;

the scale 3 is a millimeter scale and is fixed on the support 6, the plane of the scale 3 is perpendicular to the emergent ray of the laser 1, and the zero scale line of the scale is on the same horizontal plane with the emergent ray of the laser 1 and the midpoint of the parallel flat plate.

As shown in FIG. 2, let D be the thickness of the parallel plates and n be the refractive index. When the parallel plate is inclined, the incident light and the parallel plate form a certain included angle, and the first boundary incident angle is set as I₁The exit angle is I₁', the first boundary incident angle is I₂The exit angle is I₂' it is easy to know that the outgoing light rays passing through the parallel plates are parallel to the incoming light rays, but there is some lateral displacement.

Lateral displacement AC ═ AB · sin (I)₁-I₁') and AB ═ D/cos (I)₁')，

Thus is provided with

Using the formula sin (I) for the sum and difference angles in the trigonometric function₁-I₁')＝sin(I₁)cos(I₁')-cos(I₁)sin(I₁')

And refractive index definition formula

Further simplified, have

When the angle of rotation of the parallel plates is small enough, it is approximately I₁＝I₁', so there is cos (I)₁)＝cos(I₁')，sin(I₁)＝I₁。

Under the above conditions, the lateral displacement can be further expressed as

At the moment, the light is paraxial light, the axial displacement is irrelevant to the incident angle, and the imaging is perfected.

When measuring, as shown in fig. 3, when the lower end of the first toe of the optical lever is slightly displaced by Δ L, the optical lever and the parallel flat plate optical lever are tilted by Δ α, and approximately Δ α is Δ L/L, where L is the vertical distance between the first toe and the connecting line of the second toe and the third toe of the optical lever, and Δ α is easily obtained as I₁. When the parallel flat plate is inclined, the imaging position of the first word cursor on the scale is changed, the scale change amount Δ m of the first word cursor is recorded, Δ m is easy to obtain as AC, and the micro displacement can be obtained according to the above formulas

From this equation, the small displacement Δ l can be calculated.

The principle of the invention is as follows: the invention utilizes the optical characteristics of the parallel flat plate and the principle of the amplification characteristic of the optical lever to amplify small physical quantities such as micro displacement, micro angle and the like and then carry out indirect measurement. The optical characteristic of the parallel flat plate is that when the incident light and the section of the parallel flat plate have a non-right angle included angle, the light can have a broken lateral displacement after exiting the parallel flat plate. One end of the optical lever can sense small physical quantities such as tiny displacement and tiny angle, and the other end can change the position of the optical element above the optical lever, thereby generating measurable change quantity in the system. The parallel light plate can be used as an optical element on the optical lever to well utilize the characteristics of the parallel light plate and the optical element, and the measurement of small physical quantities such as small displacement, small angle and the like can be realized.

Although the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to the above-described embodiments, which are merely illustrative and not restrictive, and those skilled in the art can make many modifications without departing from the spirit and scope of the present invention as defined in the appended claims.

Claims

1. a light lever measuring system based on a parallel plate, comprising laser, light lever, ruler, support and object to be measured, it is characterized in that: described laser is a line laser, and a line laser is fixed on the support, The output light of the one-line laser is horizontal light;

The light lever is provided with a first toe below one end, and the first toe is in contact with the object to be measured; the other end of the light lever is provided with a second toe and a third toe, which are fixed on the upper part of the light lever There is a parallel plate, the light lever is perpendicular to the parallel plate, the second toe and the third toe are symmetrically distributed at the two bottom corners of the parallel plate, and the first toe is arranged in a "T" shape, and the second toe is arranged in a "T" shape. and the third toe are placed on the fixed platform; when the optical lever is in a horizontal state, the outgoing light of the in-line laser is perpendicular to the parallel plate; when the parallel plate is inclined, the incident light passing through the parallel plate and the parallel plate produce a certain amount of light. Included angle, the outgoing ray passing through the parallel plate is parallel to the incident ray, but there is a certain lateral displacement, and the position of the outgoing ray on the scale plane of the scale changes;

The scale plane of the scale is perpendicular to the outgoing light of the inline laser.

2 . The optical lever measuring system according to claim 1 , wherein the height of the bracket can be adjusted. 3 .