CN113188454A - Displacement sensor based on time difference and measuring method thereof - Google Patents

Abstract

The invention provides a displacement sensor based on time difference and a measuring method thereof, wherein the displacement sensor based on the time difference comprises the following components: the first reflecting mirror is used for receiving the laser beam reflected by the first reflecting surface of the triangular wave reflecting mirror and reflecting the laser beam to the second reflecting surface of the triangular wave reflecting mirror along the same path in the measuring process; the first optical deflector is used for enabling the incident angle of the laser beam reflected by the second reflecting surface of the triangular wave reflecting mirror to deflect at a constant speed in a set angle interval; the first photoelectric detector and the second photoelectric detector are used for receiving the laser beam deflected by the first optical deflector twice in one deflection period of the first optical deflector; and the processing system is used for calculating the displacement change value of the measured object according to the time difference of the laser beams received by the first photoelectric detector and the second photoelectric detector and the deflection speed of the first optical deflector. The invention can improve the measurement precision of the displacement sensor.

Description

Displacement sensor based on time difference and measuring method thereof

Technical Field

The invention relates to the technical field of measurement, in particular to a displacement sensor based on time difference and a measurement method thereof.

Background

The new displacement measurement principle based on the optical triangulation amplification method is realized by combining a triangular wave optical Device and a high-precision phototriode (Position sensitive Device, also called a photoelectric detector) on the basis of the optical triangulation amplification method. Chinese patent No. 2018207451284 provides a tracking displacement sensor, which utilizes an optical deflector to drive a photodetector to move, so that the position of a reflected laser beam of a triangular wave reflector incident on the photodetector is always kept unchanged, the measurement accuracy of the displacement sensor based on time difference is improved, and the amplification factor of the displacement sensor is increased. However, all movements are inertial, and the inertia of the mechanical moving structure can reduce the measuring speed, so that the measuring device cannot be applied to the field of high-speed movement measurement.

Disclosure of Invention

The invention aims to provide a displacement sensor based on time difference, which can improve the measurement accuracy.

In order to achieve the purpose, the invention provides the following technical scheme:

a time difference based displacement sensor comprising:

a triangular wave reflector including a first reflecting surface and a second reflecting surface;

a first laser beam is incident to a first reflecting surface of the triangular wave reflecting mirror;

the first reflecting mirror is used for receiving a laser beam reflected by a first reflecting surface of the triangular wave reflecting mirror and reflecting the laser beam to a second reflecting surface of the triangular wave reflecting mirror along the same path in the measuring process that the laser beam is incident to the same first reflecting surface;

the first optical deflector is used for enabling the incident angle of the laser beam reflected by the second reflecting surface of the triangular wave reflecting mirror to deflect at a constant speed in a set angle interval;

the first photoelectric detector and the second photoelectric detector are used for receiving the laser beam deflected by the first optical deflector;

and the processing system is used for calculating the displacement change value of the measured object according to the time difference of the laser beams received by the first photoelectric detector and the second photoelectric detector and the deflection speed of the first optical deflector.

In one embodiment, the first reflecting surface and the second reflecting surface of the triangular wave reflecting mirror respectively form an angle of 150 degrees with the horizontal plane, the first incident angle of the laser beam to the first reflecting surface is 30 degrees, and the first reflecting mirror is parallel to the first reflecting surface.

Preferably, the above time difference-based displacement sensor further includes:

the second laser beam is incident to the first reflecting surface of the triangular wave reflecting mirror, and the initial incident point positions of the first laser beam and the second laser beam on the first reflecting surface are different;

the second reflecting mirror is used for receiving the laser beam reflected by the first reflecting surface of the triangular wave reflecting mirror and reflecting the laser beam to the second reflecting surface of the triangular wave reflecting mirror along the same path in the measuring process that the second laser beam is incident to the same first reflecting surface;

the second optical deflector is used for enabling the incident angle of the laser beam reflected by the second reflecting surface of the triangular wave reflecting mirror to deflect at a constant speed in a set angle interval;

the photoelectric detector III and the photoelectric detector IV are used for receiving the laser beam deflected by the optical deflector II;

the processing system is specifically used for calculating the displacement change value of the measured object according to the time difference of the laser beam received by the first photoelectric detector and the time difference of the laser beam received by the second photoelectric detector and the deflection speed of the first optical deflector; or, the displacement change value of the object to be measured is calculated according to the time difference of the laser beams received by the third photoelectric detector and the fourth photoelectric detector and the deflection speed of the second optical deflector.

The method for measuring the displacement by using the displacement sensor based on the time difference comprises the following steps:

fixing a measured object on a triangular wave reflector or a measuring head;

adjusting the position relation of the first laser beam, the first triangular wave reflector, the first optical deflector, the first photoelectric detector and the second photoelectric detector to enable the first reflector to receive the first laser beam reflected by the first reflecting surface of the first triangular wave reflector, reflect the first laser beam to the second reflecting surface of the first triangular wave reflector along the same path in the measuring process of the first laser beam incident to the same first reflecting surface, and enable the first photoelectric detector and the second photoelectric detector to be in the deflection interval of the first optical deflector;

step three, starting the first optical deflector to rotate at a constant speed, emitting a first laser beam, sequentially detecting the first laser beam by the first photoelectric detector and the second photoelectric detector twice in a deflection period after the first laser beam passes through the first reflecting surface of the triangular wave reflector, the first reflecting surface of the reflector and the second reflecting surface of the triangular wave reflector, and recording the time for detecting the first laser beam;

step four, the measured object moves, and in the moving process, the time of detecting the laser beam by the photoelectric detector I and the photoelectric detector II in front and back twice is respectively recorded;

and step five, the processing system calculates and obtains the displacement value of the measured object according to the time difference of the laser beams received by the first photoelectric detector and the second photoelectric detector respectively and the deflection speed of the first optical deflector.

Compared with the prior art, the invention has the following beneficial effects:

the invention relates to a displacement sensor based on time difference, which utilizes a light deflector to deflect a reflected laser beam, and the reflected laser beam is received twice in a deflection period to generate time difference, along with the movement, the time difference of receiving the reflected laser beam by one photoelectric detector is increased, the time difference of receiving the reflected laser beam by the other photoelectric detector is decreased, and the displacement can be measured and calculated according to the time difference and the deflection angle. The time measurement results of the two photoelectric detectors realize differential amplification measurement, and the measurement precision is further improved.

The invention eliminates the influence of motion inertia on the measurement speed when the driver drives the photoelectric detector to track and measure by using the optical deflector, thereby improving the speed of displacement measurement.

Meanwhile, the displacement measurement is realized through the time difference, the high-precision displacement measurement can be realized through the high-precision time measurement, the displacement measurement is converted into the time measurement, and the displacement measurement with higher precision than that of the traditional displacement measurement sensor is easier to realize.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and it will be apparent to those skilled in the art that other relevant drawings can be obtained from the drawings without inventive effort.

Fig. 1 is a schematic diagram illustrating a measurement principle of a time difference-based displacement sensor having a structure provided in embodiment 1.

Fig. 2 is a schematic diagram illustrating a principle that there is a time difference between the reflected laser beams received by the photodetectors before and after the displacement.

Fig. 3 is a schematic diagram illustrating a measurement principle of a displacement sensor based on time difference in another structure provided in embodiment 2.

Fig. 4 is a schematic diagram of calculation of displacement measurement by time difference.

The reference numbers in the figures illustrate:

the laser device comprises a first laser source 1, a second laser source 2, a first laser beam 3, a second laser beam 4, a triangular wave reflector 5, a shell 6, a first photoelectric detector 7, a second photoelectric detector 8, a first reflector 9, a first optical deflector 10, a second reflector 11, a second optical deflector 12 and a third photoelectric detector 13; photodetector four 14; a first reflective surface 51 and a second reflective surface 52.

Detailed Description

The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the invention without inventive step, are within the scope of the invention.

Example 1

Referring to fig. 1, the present embodiment provides a displacement sensor based on time difference, including a first laser source 1, a first triangular wave mirror 5, a first mirror 9, a first photodetector 7, and a second photodetector 8, where the first triangular wave mirror 5 includes a plurality of reflecting surfaces, and for convenience of understanding, a reflecting surface for receiving a laser beam emitted from the first (or second) laser source is defined as a first reflecting surface, and a reflecting surface for receiving a laser beam reflected from the first (or second) reflecting mirror is defined as a second reflecting surface.

In the displacement sensor based on the time difference in this embodiment:

the laser source I1 is used for emitting a laser beam I3 and emitting the laser beam I to a first reflecting surface 51 of the triangular wave reflector 5;

the first reflecting mirror 9 is used for receiving the laser beam reflected by the first reflecting surface 51 of the first triangular wave reflecting mirror 5 from the first laser beam 3, and enabling the laser beam to be reflected to the second reflecting surface 52 of the triangular wave reflecting mirror 5 along the same path in the measuring process that the first laser beam 3 is incident to the same first reflecting surface 51;

the first optical deflector 10 is used for enabling the angle of the laser reflected by the second reflecting surface 52 of the triangular wave reflecting mirror 5 to deflect at a constant speed within a set angle interval;

a first photodetector 7 and a second photodetector 8 for receiving the laser beam deflected by the first optical deflector 10 twice in one deflection period of the first optical deflector 10; that is, the first photodetector 7 and the second photodetector 8 are both within the set angle range of the first optical deflector 10, thereby ensuring that the laser beam deflected by the first optical deflector 10 can be received.

And the processing system is used for calculating the displacement change value of the measured object according to the time difference of the laser beams received by the first photoelectric detector 7 and the second photoelectric detector 8 respectively and the deflection speed of the first optical deflector 10.

The processing system may be an arithmetic circuit composed of components, and different circuit structures are provided based on different implementation manners, but a person skilled in the art can easily implement the arithmetic circuit according to the calculation process of the processing system, so that a specific arithmetic circuit diagram is not given here. The processing system may also be a processor integrated with an arithmetic circuit, such as an STM32 series single chip microcomputer.

The purpose of the first optical deflector 10 is to deflect the incident laser beam, and in the simplest embodiment, a reflecting mirror (or a multi-surface reflecting mirror) is arranged on a rotating platform, and the rotating platform rotates to change the incident angle of the laser beam incident to the reflecting mirror, so that the deflection purpose is realized.

Preferably, the optical deflector may be a crystal of potassium tantalate niobate to achieve high frequency angular deflection.

In this embodiment, the deflection interval of the optical deflector one 10 is less than 15 degrees, that is, the set angle interval is less than 15 degrees, and the time for the optical deflector one 10 to rotate from the initial position to the end position and then return from the end position to the initial position is one deflection cycle.

In order to ensure the amplification performance of the displacement sensor based on the time difference, an included angle between a laser beam incident to the first photodetector 7 and the first photodetector 7 is preferably smaller than 45 degrees.

As shown in fig. 1, the first photodetector 7 is a phototransistor, the first laser beam 3 before displacement is shown by a solid line, the first laser beam 3 after displacement is shown by a dotted line, and the transmission path of the first laser beam 3 is as follows:

before displacement, the laser source I1 emits a laser beam I3 to the first reflecting surface 51 of the triangular wave reflecting mirror 5, the first reflecting surface 51 of the triangular wave reflecting mirror 5 reflects the laser beam I3 to the first reflecting mirror 9, the first reflecting mirror 9 reflects the laser beam reflected by the first reflecting surface 51 to the second reflecting surface 52, and the second reflecting surface 52 reflects the incident laser beam to the optical deflector I10.

In the first half of the deflection period, the first optical deflector 10 deflects the incident laser beam to the first photodetector 7 (it is assumed that the first photodetector 7 receives the laser beam first), the time when the first photodetector 7 receives the laser beam is t1, the laser beam reaches a deflection limit angle of the laser beam after rotating to a certain angle with the uniform rotation of the first optical deflector 10, and then the laser beam is deflected toward the other deflection limit angle. With the deflection movement of the laser beam, the optical deflector one 10 deflects the incident laser beam to be incident on the photodetector one 7, and the time when the photodetector one 7 receives the laser beam again is t 2.

In the second half of the deflection period, the first optical deflector 10 deflects the incident laser beam to the second photodetector 8, the time when the second photodetector 8 receives the laser beam is t3, the laser beam reaches a deflection limit angle of the light beam after rotating to a certain angle along with the uniform rotation of the first optical deflector 10, and then the laser beam is deflected towards the other deflection limit angle. With the deflection movement of the laser beam, the first optical deflector 10 deflects the incident laser beam to be incident on the second photodetector 8, and the time when the second photodetector 8 receives the laser beam again is t 4.

The time difference of receiving the laser beam by the first photodetector 10 in one deflection period before the displacement is T2-T1, and the time difference of receiving the laser beam by the second photodetector 8 in one deflection period is T2-T4-T3.

After displacement (shown as leftward displacement in fig. 1, during the displacement, the first laser source 1, the first reflector 9, the first optical deflector 10, the first photodetector 7, and the second photodetector 8 synchronously move leftward), the first laser source 1 emits a first laser beam 3 to a first reflecting surface 51 of the triangular reflector 5 (compared with another position point of the same reflecting surface before the displacement), the first reflecting surface 51 of the triangular reflector 5 reflects the first laser beam 3 to the first reflector 9, the first reflector 9 reflects the laser reflected by the first reflecting surface 51 to a second reflecting surface 52 along the same path before the displacement, and the second reflecting surface 52 reflects the incident laser beam to the first optical deflector 10 along the same path before the displacement.

The process of incidence to the first photodetector 7 and the second photodetector 8 after deflection by the first optical deflector 10 is the same as the optical path before displacement. In the first half of the deflection period, the time when the first photodetector 7 receives the laser beam for the first time is t5, and the time when the second photodetector receives the laser beam is t 6; in the second half of the deflection period, the time when the second photodetector 8 receives the laser beam for the first time is t7, and the time when the second laser beam is received for the second time is t 8. The time difference of receiving the laser beam by the first photodetector 7 in one deflection period after the displacement is T6-T5, and the time difference of receiving the laser beam by the second photodetector 8 in one deflection period is T4-T8-T7.

Referring to fig. 2, a thick solid line (i.e., the rightmost solid line) indicates a deflection limit boundary of the first optical deflector. Before the displacement, the angle between the laser beam incident on the first photodetector 7 and the deflection limit boundary is b, the angle between the laser beam incident on the first photodetector 7 after the displacement and the deflection limit boundary is a, and b is smaller than a, that is, the incident angle after the displacement is increased, so that the time difference between two times of receiving the laser beams by the first photodetector 7 before and after the displacement is correspondingly increased, that is, δ T3 is larger than δ T1.

Similarly, after the displacement, the angle between the laser beam incident on the second photodetector 8 and the deflection limit boundary becomes smaller, so that the time difference of receiving the laser beam by the second photodetector 8 before and after the displacement is correspondingly reduced, that is, δ T4 is smaller than δ T2.

And the first optical deflector 10 deflects the incident laser at a constant speed, the rotation angle of the first optical deflector 10 in unit time is known, and the displacement of the measured object can be calculated according to the deflection speed of the first optical deflector 10 and the time difference between the two photodetectors before and after displacement.

Referring to fig. 4, the calculation process is as follows: if the angular deflection speed of the optical deflector one 10 to the incident laser is α degrees/second, the receiving surface distance from the angular deflector one 10 to the photodetector one 7 is h, and the maximum deflection angle value of the angular deflector one 10 is β degrees, the angle (α × δ T3)/2 corresponding to the time difference δ T3 is obtained, and the current displacement X is h × tg (β - (α × δ T3)/2). The formula is as follows: Δ X ═ hxtg (β - (. α × δ T3)/2) -hxtg (β - (. α × δ T1)/2); when the structural parameters of the second photodetector 8 are consistent with those of the first photodetector 7, 2 Δ X ═ h × tg (β - (α × δ T3)/2) -h × tg (β - (α × δ T1)/2) + h × tg (β - (α × δ T2)/2) -h × tg (β - (α × δ T4)/2) can be obtained by using the displacement difference principle. When the structural parameter of the second photodetector 8 is not consistent with the first photodetector 7, if the distance from the first angular deflector 10 to the receiving surface of the second photodetector 8 is h ' and the maximum deflection angle value of the first angular deflector 10 is β ', 2 Δ X is hxtg (β - (α × δ T3)/2) -hxtg (β - (α × δ T1)/2) + hxtg (β ' - (α × δ T2)/2) -h ' xtg (β ' - (α × δ T4)/2).

In order to further improve the measurement accuracy, a relation curve of the time difference and the displacement can be obtained through a standard displacement calibration experiment, and a time difference delta T is obtained after the time difference delta X is moved by a fixed interval delta X. The displacement amount corresponding to any one time difference can be obtained through interpolation processing.

In order to realize that the laser beam reflected by the first mirror 9 is reflected to the second reflecting surface 52 of the triangular wave mirror 5 along the same path before and after the displacement, the following can be realized, for example: the first reflecting mirror is parallel to the first reflecting surface and the second reflecting surface, and the acute included angle between the first laser beam and the first reflecting surface is equal to twice the included angle between the first reflecting surface and the horizontal plane.

For example, as a preferred embodiment, the angles between the first reflective surface 51 and the second reflective surface 52 of the triangular wave mirror 5 and the horizontal plane are respectively 150 degrees (taking the horizontal right as a positive direction and rotating along the counterclockwise direction as an example), the incident angle of the laser beam one 3 emitted by the laser source one 1 to the first reflective surface 51 is 30 degrees, and the mirror one 9 is parallel to the first reflective surface 51. In the measurement process that the first guarantee reflector 9 enables the laser beam 3 emitted by the first laser source 1 to be incident on the same first reflection surface, under the condition that the emitted laser beam 3 is reflected to the second reflection surface 52 of the triangular wave reflector 5 along the same path, other different arrangement modes can be provided.

The triangular wave does not necessarily need an isosceles triangular wave, i.e., the acute included angles between the two reflecting surfaces forming the triangular wave and the horizontal plane may be equal or unequal. In the displacement sensor based on the time difference provided by the present embodiment, for the triangular wave reflecting mirror 5, under the condition that the first reflecting surface 51 is parallel to the second reflecting surface 52, the specific structure thereof is not limited, that is, the included angle between the two reflecting surfaces forming the triangular wave is not limited.

Referring to fig. 1, the displacement sensor based on the time difference may further include a housing 6, the first laser source 1, the first reflector 9, the first optical deflector 10, the first photodetector 7, and the second photodetector 8 are all fixedly disposed in the housing 6 to form a measuring head, and the first laser beam 3 emitted by the first laser source 1 and the reflected light beam thereof may both pass through a transmitting and receiving end surface of the measuring head. The laser source I1, the reflector I9, the optical deflector I10, the photoelectric detector I7 and the photoelectric detector II 8 are fixedly arranged in the shell 6, the positions of the laser source I, the reflector I9, the optical deflector I10, the photoelectric detector I7 and the photoelectric detector II can be kept fixed, and synchronous displacement of the laser source I, the reflector I9, the optical deflector I10, the photoelectric detector I7 and the photoelectric detector II can be guaranteed.

During measurement, the triangular wave reflecting mirror 5 can be fixed on a measured object according to actual application conditions, the measuring head keeps fixed, when the measured object displaces, the triangular wave reflecting mirror 5 and the measuring head move relatively, and the measuring head can measure to obtain the displacement value of the triangular wave reflecting mirror 5, namely the measured object. As another embodiment, the measuring head may be fixed on the measured object, the triangular wave reflecting mirror 5 remains stationary, the measured object displaces to drive the measuring head to move, the measuring head and the triangular wave reflecting mirror 5 displace relatively, and the measuring head may measure the relative displacement between the measuring head and the triangular wave reflecting mirror 5, so as to obtain the displacement value of the measured object.

The triangular wave reflector 5 or the measuring head is selected for measurement to be fixed on a measured object, so that the measurement convenience is improved.

When the displacement sensor based on the time difference is used for displacement measurement, the steps are as follows:

fixing a measured object on a triangular wave reflector or a measuring head;

adjusting the position relation of a first laser beam (namely, a first laser source), a triangular wave reflector, a first optical deflector, a first photoelectric detector and a second photoelectric detector, so that the first reflector receives the laser beam reflected by a first reflecting surface of the triangular wave reflector, the laser beam is reflected to a second reflecting surface of the triangular wave reflector along the same path in the measuring process that the first laser beam is incident to the same first reflecting surface, and the first photoelectric detector and the second photoelectric detector are in the deflection interval of the first optical deflector, namely, the first photoelectric detector and the second photoelectric detector can receive the laser beam reflected by the second reflecting surface of the triangular wave reflector in the rotating process of the first optical deflector;

step three, starting the first optical deflector to rotate at a constant speed, emitting a first laser beam, sequentially detecting the first laser beam by the first photoelectric detector and the second photoelectric detector twice in a deflection period after the first laser beam passes through the first reflecting surface of the triangular wave reflector, the first reflecting surface of the reflector and the second reflecting surface of the triangular wave reflector, and recording the time for detecting the first laser beam;

step four, the measured object moves, and in the moving process, the time of detecting the laser beam by the photoelectric detector I and the photoelectric detector II in front and back twice is respectively recorded;

and step five, the processing system calculates and obtains the displacement value of the measured object according to the time difference of the laser beams received by the first photoelectric detector and the second photoelectric detector respectively and the deflection speed of the first optical deflector.

Example 2

Referring to fig. 3, compared to the time difference-based displacement sensor described in embodiment 1, the time difference-based displacement sensor provided in this embodiment further includes a second laser beam 4 incident on another first reflecting surface 51 of the triangular wave reflecting mirror 5; and the following components:

the second reflecting mirror 11 is used for receiving the laser beam, reflected by the second first reflecting surface 51 of the triangular wave reflecting mirror 5, of the second laser beam 4 and reflecting the laser beam to the second reflecting surface 52 of the triangular wave reflecting mirror 5 along the same path in the measurement process that the second laser beam 4 is incident to the first reflecting surface 51;

a second optical deflector 12 for deflecting the incident angle of the laser beam reflected by the second reflecting surface 52 of the triangular wave mirror 5 at a constant speed within a set angle interval;

a third photodetector 13 and a fourth photodetector 14 for receiving the laser beam deflected by the second optical deflector twice in one deflection period of the second optical deflector;

in the displacement sensor based on the time difference according to this embodiment, the processing system calculates the displacement variation value of the object to be measured according to the time difference between the laser beam received by the first photodetector 7 and the laser beam received by the second photodetector 8, and the deflection speed of the first optical deflector 10; alternatively, the displacement change value of the object to be measured is calculated from the time difference between the laser beam received by the third photodetector 13 and the laser beam received by the fourth photodetector 14, and the deflection speed of the second optical deflector 12.

The displacement sensor based on the time difference in the embodiment can realize continuous displacement measurement. Specifically, one of the two laser beams can be selected for measurement, when one of the reflection points of the laser beam is located at some positions of the reflection surface, such as the top of the reflection surface, the intersection line position of the two reflection surfaces, etc., the light path of the reflected laser beam is changed, and therefore the reflected laser beam may not be reflected to the corresponding photodetector, and the other reflection point of the laser beam is located at other positions of the other reflection surface, and may be reflected to the corresponding photodetector, and each moment of the movement of the measured object can be realized, at least one of the laser beams reflected by each second reflection surface 52 on the triangular wave reflection mirror 5 may be reflected to the corresponding photodetector, at this time, the processing system may switch back and forth to calculate the time difference between the two sets of photodetectors, and perform superposition accumulation, so as to realize the measurement of the displacement of the measured object by one-time change or continuous incremental displacement change, the measurement method is simple, reliable, and convenient to operate, and the measurement accuracy can be improved.

As shown in fig. 3, the laser beam one 3 and the laser beam two 4 are respectively emitted by the laser source one 1 and the laser source two 2.

The two measuring systems can be arranged in a shell to form a measuring head, and also can be respectively arranged in a shell to form two measuring heads. Specifically, a first laser source, a second laser source, a first reflector, a second reflector, a first optical deflector, a second optical deflector, a first photoelectric detector, a second photoelectric detector, a third photoelectric detector and a fourth photoelectric detector are all fixedly arranged in a shell to form a measuring head. Or the first laser source, the first reflector, the first optical deflector, the first photoelectric detector and the second photoelectric detector are all fixedly arranged in a shell to form a measuring head; the laser source II, the reflector II, the optical deflector II, the photoelectric detector III and the photoelectric detector IV are all fixedly arranged in the other shell to form the other measuring head.

It is easy to understand that in this embodiment, the first laser source and the second laser source are arranged to avoid that when one of the photodetectors cannot receive the laser beam, the other photodetector can receive the laser beam to achieve displacement measurement, so that in addition to the arrangement shown in fig. 3, there may be other arrangement manners as long as the first laser source and the second laser source are arranged in a staggered manner, so that the initial incident point positions of the first laser beam and the second laser beam on the first reflection surface are different, for example, the second laser beam may be incident on another first reflection surface on the same side as the first reflection surface on which the first laser beam is incident, and may be incident on the same reflection surface on which the first laser beam is incident, but the incident point positions are different.

The photodetectors (one to four) may be position sensitive detector phototriodes, or devices such as photodiodes, photocells, etc.

When the displacement sensor based on the time difference in the embodiment is applied to displacement measurement, the steps are as follows:

fixing a measured object on a triangular wave reflector or a measuring head;

adjusting the position relation of the first laser beam, the first triangular wave reflector, the first optical deflector, the first photoelectric detector and the second photoelectric detector to enable the first reflector to receive the first laser beam reflected by the first reflecting surface of the first triangular wave reflector, reflect the first laser beam to the second reflecting surface of the first triangular wave reflector along the same path in the measuring process of the first laser beam incident to the same first reflecting surface, and enable the first photoelectric detector and the second photoelectric detector to be in the deflection interval of the first optical deflector; adjusting the position relation of the second laser beam, the second triangular wave reflector, the second optical deflector, the third photoelectric detector and the fourth photoelectric detector, so that the second reflector receives the laser beam reflected by the first reflecting surface of the second triangular wave reflector, the laser beam is reflected to the second reflecting surface of the triangular wave reflector along the same path in the measuring process that the second laser beam is incident to the same first reflecting surface, and the third photoelectric detector and the fourth photoelectric detector are in the deflection interval of the second optical deflector;

step three, starting the first optical deflector to rotate at a constant speed, emitting a first laser beam, sequentially detecting the first laser beam by the first photoelectric detector and the second photoelectric detector twice in a deflection period after the first laser beam passes through the first reflecting surface of the triangular wave reflector, the first reflecting surface of the reflector and the second reflecting surface of the triangular wave reflector, and recording the time for detecting the first laser beam; or starting the second optical deflector to rotate at a constant speed, emitting a second laser beam, sequentially passing through the first reflecting surface of the triangular wave reflector, the second reflecting surface of the reflector and the second reflecting surface of the triangular wave reflector, sequentially detecting the laser beams by the third photoelectric detector and the fourth photoelectric detector twice in a deflection period, and recording the time for detecting the laser beams;

step four, the measured object is displaced, and in the displacement process, the time of detecting the laser beam by the photoelectric detector I and the time of detecting the laser beam by the photoelectric detector II are respectively recorded, or the time of detecting the laser beam by the photoelectric detector III and the time of detecting the laser beam by the photoelectric detector IV are respectively recorded;

step five, the processing system calculates and obtains the displacement value of the measured object according to the time difference of the laser beams received by the first photoelectric detector and the second photoelectric detector respectively and the deflection speed of the first optical deflector; or measuring and calculating to obtain the displacement value of the measured object according to the time difference of the laser beams received by the third photoelectric detector and the fourth photoelectric detector respectively and the deflection speed of the second optical deflector.

The above description is only an embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of changes or substitutions within the technical scope of the present invention, and the present invention should be covered by the scope of the present invention.

Claims (10)

1. A time difference based displacement sensor, comprising:

a triangular wave reflector including a first reflecting surface and a second reflecting surface;

a first laser beam is incident to a first reflecting surface of the triangular wave reflecting mirror;

the first reflecting mirror is used for receiving a laser beam reflected by a first reflecting surface of the triangular wave reflecting mirror and reflecting the laser beam to a second reflecting surface of the triangular wave reflecting mirror along the same path in the measuring process that the laser beam is incident to the same first reflecting surface;

the first optical deflector is used for enabling the incident angle of the laser beam reflected by the second reflecting surface of the triangular wave reflecting mirror to deflect at a constant speed in a set angle interval;

the first photoelectric detector and the second photoelectric detector are used for receiving the laser beam deflected by the first optical deflector twice in one deflection period of the first optical deflector;

and the processing system is used for calculating the displacement change value of the measured object according to the time difference of the laser beams received by the first photoelectric detector and the second photoelectric detector and the deflection speed of the first optical deflector.

2. A time difference based displacement sensor according to claim 1, wherein the first reflecting mirror is parallel to the first reflecting surface and parallel to the second reflecting surface, and the acute angle of the first laser beam to the first reflecting surface is equal to twice the angle of the first reflecting surface to the horizontal.

3. The time difference based displacement sensor according to claim 2, wherein the first reflecting surface and the second reflecting surface of the triangular wave reflecting mirror respectively form an angle of 150 degrees with the horizontal plane, and the first incident angle of the laser beam to the first reflecting surface is 30 degrees.

4. The displacement sensor based on the time difference is characterized by further comprising a shell, the first laser beam is obtained by emitting of the first laser source, and the first laser source, the first reflecting mirror, the first photoelectric detector and the second photoelectric detector are fixedly arranged in the shell to form a measuring head.

5. The time difference based displacement sensor of any one of claims 1-4, further comprising:

the second laser beam is incident to the first reflecting surface of the triangular wave reflecting mirror, and the initial incident point positions of the first laser beam and the second laser beam on the first reflecting surface are different;

the second reflecting mirror is used for receiving the laser beam reflected by the first reflecting surface of the triangular wave reflecting mirror and reflecting the laser beam to the second reflecting surface of the triangular wave reflecting mirror along the same path in the measuring process that the second laser beam is incident to the same first reflecting surface;

the second optical deflector is used for enabling the incident angle of the laser beam reflected by the second reflecting surface of the triangular wave reflecting mirror to deflect at a constant speed in a set angle interval;

the photoelectric detector III and the photoelectric detector IV are used for receiving the laser beams deflected by the optical deflector II twice in one deflection period of the optical deflector II;

the processing system is specifically used for calculating the displacement change value of the measured object according to the time difference of the laser beam received by the first photoelectric detector and the time difference of the laser beam received by the second photoelectric detector and the deflection speed of the first optical deflector; or, the displacement change value of the measured object is calculated according to the time difference of the laser beams received by the third photoelectric detector and the fourth photoelectric detector and the deflection speed of the second optical deflector.

6. The time difference based displacement sensor of claim 5, wherein the first laser beam and the second laser beam are respectively incident on two different first reflection surfaces of the triangular wave reflecting mirror.

7. The displacement sensor based on the time difference as claimed in claim 5, further comprising a housing, wherein the first laser beam and the second laser beam are respectively emitted by a first laser source and a second laser source, and the first laser source, the second laser source, the first reflector, the second reflector, the first optical deflector, the second optical deflector, the first photodetector, the second photodetector, the third photodetector, and the fourth photodetector are all fixedly arranged in the housing to form a measuring head.

8. The displacement sensor based on the time difference as claimed in claim 5, further comprising two housings, wherein the first laser beam and the second laser beam are respectively emitted by the first laser source and the second laser source, the first reflector, the first optical deflector, the first photodetector and the second photodetector are all fixedly disposed in one housing to form one measuring head, and the second laser source, the second reflector, the second optical deflector, the third photodetector and the fourth photodetector are all fixedly disposed in the other housing to form the other measuring head.

9. The method for displacement measurement using the time difference based displacement sensor of claim 1, comprising the steps of:

fixing a measured object on a triangular wave reflector or a measuring head;

adjusting the position relation of the first laser beam, the first triangular wave reflector, the first optical deflector, the first photoelectric detector and the second photoelectric detector to enable the first reflector to receive the first laser beam reflected by the first reflecting surface of the first triangular wave reflector, reflect the first laser beam to the second reflecting surface of the first triangular wave reflector along the same path in the measuring process of the first laser beam incident to the same first reflecting surface, and enable the first photoelectric detector and the second photoelectric detector to be in the deflection interval of the first optical deflector;

step three, starting the first optical deflector to rotate at a constant speed, emitting a first laser beam, sequentially detecting the first laser beam by the first photoelectric detector and the second photoelectric detector twice in a deflection period after the first laser beam passes through the first reflecting surface of the triangular wave reflector, the first reflecting surface of the reflector and the second reflecting surface of the triangular wave reflector, and recording the time for detecting the first laser beam;

step four, the measured object moves, and in the moving process, the time of detecting the laser beam by the photoelectric detector I and the photoelectric detector II in front and back twice is respectively recorded;

and step five, the processing system calculates and obtains the displacement value of the measured object according to the time difference of the laser beams received by the first photoelectric detector and the second photoelectric detector respectively and the deflection speed of the first optical deflector.

10. The method for displacement measurement using the time difference based displacement sensor according to claim 5, comprising the steps of:

fixing a measured object on a triangular wave reflector or a measuring head;

adjusting the position relation of the first laser beam, the first triangular wave reflector, the first optical deflector, the first photoelectric detector and the second photoelectric detector to enable the first reflector to receive the first laser beam reflected by the first reflecting surface of the first triangular wave reflector, reflect the first laser beam to the second reflecting surface of the first triangular wave reflector along the same path in the measuring process of the first laser beam incident to the same first reflecting surface, and enable the first photoelectric detector and the second photoelectric detector to be in the deflection interval of the first optical deflector; adjusting the position relation of the second laser beam, the second triangular wave reflector, the second optical deflector, the third photoelectric detector and the fourth photoelectric detector, so that the second reflector receives the laser beam reflected by the first reflecting surface of the second triangular wave reflector, the laser beam is reflected to the second reflecting surface of the triangular wave reflector along the same path in the measuring process that the second laser beam is incident to the same first reflecting surface, and the third photoelectric detector and the fourth photoelectric detector are in the deflection interval of the second optical deflector;

step three, starting the first optical deflector to rotate at a constant speed, emitting a first laser beam, sequentially detecting the first laser beam by the first photoelectric detector and the second photoelectric detector twice in a deflection period after the first laser beam passes through the first reflecting surface of the triangular wave reflector, the first reflecting surface of the reflector and the second reflecting surface of the triangular wave reflector, and recording the time for detecting the first laser beam; or starting the second optical deflector to rotate at a constant speed, emitting a second laser beam, sequentially passing through the first reflecting surface of the triangular wave reflector, the second reflecting surface of the reflector and the second reflecting surface of the triangular wave reflector, sequentially detecting the laser beams by the third photoelectric detector and the fourth photoelectric detector twice in a deflection period, and recording the time for detecting the laser beams;

step four, the measured object is displaced, and in the displacement process, the time of detecting the laser beam by the first photoelectric detector and the time of detecting the laser beam by the second photoelectric detector in the front and back two times are respectively recorded, or the time of detecting the laser beam by the third photoelectric detector and the time of detecting the laser beam by the fourth photoelectric detector 14 in the front and back two times are respectively recorded;

step five, the processing system calculates and obtains the displacement value of the measured object according to the time difference of the laser beams received by the first photoelectric detector and the second photoelectric detector respectively and the deflection speed of the first optical deflector; or measuring and calculating to obtain the displacement value of the measured object according to the time difference of the laser beams received by the third photoelectric detector and the fourth photoelectric detector respectively and the deflection speed of the second optical deflector.

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