1. An optical multi-path nanoscale displacement measurement system, comprising: the device comprises a light source, a polarization beam splitter prism, a first phase change module, a second phase change module, a first right-angle prism, a second right-angle prism and a displacement measurement module;

the light source is used for emitting laser;

the polarization beam splitter prism is used for splitting the laser into first transmitted light and first reflected light;

the object to be detected is arranged on the emergent light path of the first phase change module;

the first phase change module is to:

changing the phase of the first transmission light, and transmitting the first transmission light after the phase change to the object to be detected;

receiving first light to be detected reflected by the object to be detected, changing the phase of the first light to be detected to obtain second reflected light, and sending the second reflected light to the polarization beam splitter prism;

the second phase change module is arranged on an emergent light path of the first reflected light;

the second phase altering module is to:

changing the phase and direction of the first reflected light to obtain second transmitted light, and sending the second transmitted light to the polarization beam splitter prism;

the polarization beam splitter prism is further used for converging the second reflected light and the second transmitted light to obtain first converged light;

the first right-angle prism is arranged on an emergent light path of the first converging light; the first right-angle prism is used for reversing the direction of the first converged light to obtain first reversed light;

the polarization beam splitter prism is also used for splitting the first turnover light into third transmission light and third reflection light;

the first phase change module is further to:

changing the phase of the third reflected light, and transmitting the phase-changed third reflected light to the object to be detected;

receiving second light to be measured reflected by the object to be measured, changing the phase of the second light to be measured to obtain fourth transmission light, and sending the fourth transmission light to the polarization beam splitter prism;

the second phase altering module is further configured to:

changing the phase and direction of the third transmitted light to obtain fourth reflected light, and sending the fourth reflected light to the polarization beam splitter prism;

the polarization beam splitter prism is further used for converging the fourth transmitted light and the fourth reflected light to obtain second converged light;

the second right-angle prism is arranged on an emergent light path of the second converging light; the second right-angle prism is used for reversing the direction of the second converged light to obtain second reversed light;

the polarization beam splitter prism is further used for splitting the second turnover light into fifth transmission light and fifth reflection light;

the displacement measurement module is used for:

receiving the fifth transmitted light and the fifth reflected light, and performing vortex interference on the fifth transmitted light and the fifth reflected light to obtain interference vortex rotation;

and calculating the displacement of the object to be detected according to the interference vortex optical rotation in the position moving process of the object to be detected.

2. The optical multi-range nanoscale displacement measurement system of claim 1, wherein said displacement measurement module comprises: the device comprises a first vortex light generation unit, a second vortex light generation unit, a non-polarization beam splitter prism, a photoelectric detector and a calculation unit;

the first vortex light generating unit is arranged on an emergent light path of the fifth reflected light and is used for converting the fifth reflected light into a first vortex rotation;

the second vortex light generating unit is arranged on an emergent light path of the fifth transmitted light and is used for converting the fifth transmitted light into a second vortex rotation;

the non-polarization beam splitter prism is arranged at the junction of the emergent light path of the first vortex rotation and the emergent light path of the second vortex rotation, and the non-polarization beam splitter prism is used for interfering the first vortex rotation and the second vortex rotation to obtain the interference vortex rotation;

the photoelectric detector is arranged on an emergent light path of the interference vortex optical rotation and is used for detecting the light intensity of the interference vortex optical rotation in the position moving process of the object to be detected to obtain a light intensity change curve;

the calculation unit is connected with the photoelectric detector and used for determining the displacement of the object to be detected according to the light intensity change curve.

3. The optical multi-range nanoscale displacement measurement system of claim 1, wherein said first phase-altering module comprises: a first quarter wave plate; the first quarter wave plate is arranged on an emergent light path of the first transmitted light and is positioned between the polarization beam splitter prism and the object to be detected;

the first quarter wave plate is used for changing the phase of light passing through the first quarter wave plate.

4. The optical multi-range nanoscale displacement measurement system of claim 3, wherein said first phase-altering module further comprises: a first planar mirror; the first plane reflector is arranged on the emergent light path of the first quarter wave and is positioned on the surface of the object to be detected;

the first plane mirror is used for reflecting the light reaching the first plane mirror to the first quarter-wave plate.

5. The optical multi-range nanoscale displacement measurement system of claim 1, wherein said second phase altering module comprises: a second quarter-wave plate and a second plane mirror; the second plane reflector is arranged on the emergent light path of the first reflected light, and the second quarter wave plate is arranged on the emergent light path of the first reflected light and is positioned between the polarization beam splitter prism and the second plane reflector;

the second quarter-wave plate is used for changing the phase of the light passing through the second quarter-wave plate;

the second plane mirror is used for reflecting the light reaching the second plane mirror to the first two-quarter wave plate.

6. The optical multi-range nanoscale displacement measurement system of claim 2, wherein said first vortex light generating unit comprises: a first vortex half-wave plate and a dove prism;

the first vortex half-wave plate is arranged on an emergent light path of the fifth reflected light and is used for converting the fifth reflected light into a third vortex optical rotation;

the dove prism is arranged on an emergent light path of the third vortex optical rotation and used for turning the phase of the third vortex optical rotation by 180 degrees to obtain a first vortex optical rotation.

7. The optical multi-range nanoscale displacement measurement system of claim 6, wherein said second vortex light generating unit comprises: a second vortex half-wave plate; the second vortex half-wave plate is arranged on an emergent light path of the fifth transmitted light;

the second vortex half-wave plate is used for converting the fifth transmission light into a second vortex rotation.

8. The optical multi-range nanoscale displacement measurement system of claim 7, wherein said first vortex light generating unit further comprises: a third right-angle prism; the third right-angle prism is arranged on an emergent light path of the fifth reflected light and is positioned between the polarization beam splitter prism and the first vortex half-wave plate;

the third right-angle prism is used for changing the direction of the fifth reflected light;

the second vortex light generating unit further includes: a fourth right-angle prism; the fourth right-angle prism is arranged on an emergent light path of the fifth transmission light and is positioned between the polarization beam splitter prism and the second vortex half-wave plate;

the fourth right-angle prism is used for changing the direction of the fifth transmission light.

9. The optical multi-range nanoscale displacement measurement system of claim 2, wherein said displacement measurement module further comprises: a laser beam expander; the laser beam expander is arranged on an emergent light path of the interference vortex optical rotation and is positioned between the non-polarization beam splitter prism and the photoelectric detector;

the laser beam expander is used for amplifying the interference vortex optical rotation.

10. The optical multi-octave nanoscale displacement measurement system of claim 6, wherein the first vortex half-wave plate and the second vortex half-wave plate are topologically equally charged.

Background

The vortex light beam is a typical representation in a vector light field, has a spiral wave front phase distribution and a circular light intensity distribution, and carries certain orbital angular momentum. In 1989, the term "optical vortex" was first introduced. In 1992, it was first proposed that the vortex beam have orbital angular momentum under paraxial conditions, and the value of the average orbital angular momentum per photon was quantified as the product of the value of the topological charge of the vortex beam and the planck constant.

Like a scalar light field, vortex light beams can also generate physical phenomena such as interference, but different from the scalar light field, interference fringes after two vortex light beams are interfered are distributed in a petal shape, and meanwhile, when the optical path difference of the two vortex light beams which are interfered is changed, the petal-shaped interference fringes can rotate. Based on the principle, the interference of vortex beams can be utilized to carry out the accurate measurement of micro-nano displacement. In 2017, based on the Michelson interferometer principle, a vortex light beam is used for generating a petal-shaped interference signal, and the micro displacement is accurately measured by detecting the rotation angle of an interference petal image. In 2020, accurate measurement of micro-nano displacement is realized by using interference images of spherical waves and vortex light beams.

Compared with the traditional scalar light field original interference signal, the measurement of micro-nano displacement based on vortex light field interference realizes higher subdivision multiple, and meanwhile, the quality of interpolation subdivision is improved because the circumference has a natural reference of 360 degrees. However, at present, micro-nano displacement measurement based on vector vortex light field interference mostly uses a light path design with an optical path difference of two times, and the resolution of displacement measurement is still low.

Disclosure of Invention

The invention aims to provide an optical multi-range nanoscale displacement measurement system, which improves the resolution of displacement measurement.

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

an optical multi-path nanoscale displacement measurement system comprising: the device comprises a light source, a polarization beam splitter prism, a first phase change module, a second phase change module, a first right-angle prism, a second right-angle prism and a displacement measurement module;

the light source is used for emitting laser;

the polarization beam splitter prism is used for splitting the laser into first transmitted light and first reflected light;

the object to be detected is arranged on the emergent light path of the first phase change module;

the first phase change module is to:

changing the phase of the first transmission light, and transmitting the first transmission light after the phase change to the object to be detected;

receiving first light to be detected reflected by the object to be detected, changing the phase of the first light to be detected to obtain second reflected light, and sending the second reflected light to the polarization beam splitter prism;

the second phase change module is arranged on an emergent light path of the first reflected light;

the second phase altering module is to:

changing the phase and direction of the first reflected light to obtain second transmitted light, and sending the second transmitted light to the polarization beam splitter prism;

the polarization beam splitter prism is further used for converging the second reflected light and the second transmitted light to obtain first converged light;

the first right-angle prism is arranged on an emergent light path of the first converging light; the first right-angle prism is used for reversing the direction of the first converged light to obtain first reversed light;

the polarization beam splitter prism is also used for splitting the first turnover light into third transmission light and third reflection light;

the first phase change module is further to:

changing the phase of the third reflected light, and transmitting the phase-changed third reflected light to the object to be detected;

receiving second light to be measured reflected by the object to be measured, changing the phase of the second light to be measured to obtain fourth transmission light, and sending the fourth transmission light to the polarization beam splitter prism;

the second phase altering module is further configured to:

changing the phase and direction of the third transmitted light to obtain fourth reflected light, and sending the fourth reflected light to the polarization beam splitter prism;

the polarization beam splitter prism is further used for converging the fourth transmitted light and the fourth reflected light to obtain second converged light;

the second right-angle prism is arranged on an emergent light path of the second converging light; the second right-angle prism is used for reversing the direction of the second converged light to obtain second reversed light;

the polarization beam splitter prism is further used for splitting the second turnover light into fifth transmission light and fifth reflection light;

the displacement measurement module is used for:

receiving the fifth transmitted light and the fifth reflected light, and performing vortex interference on the fifth transmitted light and the fifth reflected light to obtain interference vortex rotation;

and calculating the displacement of the object to be detected according to the interference vortex optical rotation in the position moving process of the object to be detected.

Optionally, the displacement measuring module includes: the device comprises a first vortex light generation unit, a second vortex light generation unit, a non-polarization beam splitter prism, a photoelectric detector and a calculation unit;

the first vortex light generating unit is arranged on an emergent light path of the fifth reflected light and is used for converting the fifth reflected light into a first vortex rotation;

the second vortex light generating unit is arranged on an emergent light path of the fifth transmitted light and is used for converting the fifth transmitted light into a second vortex rotation;

the non-polarization beam splitter prism is arranged at the junction of the emergent light path of the first vortex rotation and the emergent light path of the second vortex rotation, and the non-polarization beam splitter prism is used for interfering the first vortex rotation and the second vortex rotation to obtain the interference vortex rotation;

the photoelectric detector is arranged on an emergent light path of the interference vortex optical rotation and is used for detecting the light intensity of the interference vortex optical rotation in the position moving process of the object to be detected to obtain a light intensity change curve;

the calculation unit is connected with the photoelectric detector and used for determining the displacement of the object to be detected according to the light intensity change curve.

Optionally, the first phase changing module includes: a first quarter wave plate; the first quarter wave plate is arranged on an emergent light path of the first transmitted light and is positioned between the polarization beam splitter prism and the object to be detected;

the first quarter wave plate is used for changing the phase of light passing through the first quarter wave plate.

Optionally, the first phase changing module further includes: a first planar mirror; the first plane reflector is arranged on the emergent light path of the first quarter wave and is positioned on the surface of the object to be detected;

the first plane mirror is used for reflecting the light reaching the first plane mirror to the first quarter-wave plate.

Optionally, the second phase changing module includes: a second quarter-wave plate and a second plane mirror; the second plane reflector is arranged on the emergent light path of the first reflected light, and the second quarter wave plate is arranged on the emergent light path of the first reflected light and is positioned between the polarization beam splitter prism and the second plane reflector;

the second quarter-wave plate is used for changing the phase of the light passing through the second quarter-wave plate;

the second plane mirror is used for reflecting the light reaching the second plane mirror to the first two-quarter wave plate.

Optionally, the first vortex light generating unit includes: a first vortex half-wave plate and a dove prism;

the first vortex half-wave plate is arranged on an emergent light path of the fifth reflected light and is used for converting the fifth reflected light into a third vortex optical rotation;

the dove prism is arranged on an emergent light path of the third vortex optical rotation and used for turning the phase of the third vortex optical rotation by 180 degrees to obtain a first vortex optical rotation.

Optionally, the second vortex light generating unit includes: a second vortex half-wave plate; the second vortex half-wave plate is arranged on an emergent light path of the fifth transmitted light;

the second vortex half-wave plate is used for converting the fifth transmission light into a second vortex rotation.

Optionally, the first vortex light generating unit further includes: a third right-angle prism; the third right-angle prism is arranged on an emergent light path of the fifth reflected light and is positioned between the polarization beam splitter prism and the first vortex half-wave plate;

the third right-angle prism is used for changing the direction of the fifth reflected light;

the second vortex light generating unit further includes: a fourth right-angle prism; the fourth right-angle prism is arranged on an emergent light path of the fifth transmission light and is positioned between the polarization beam splitter prism and the second vortex half-wave plate;

the fourth right-angle prism is used for changing the direction of the fifth transmission light.

Optionally, the displacement measuring module further includes: a laser beam expander; the laser beam expander is arranged on an emergent light path of the interference vortex optical rotation and is positioned between the non-polarization beam splitter prism and the photoelectric detector;

the laser beam expander is used for amplifying the interference vortex optical rotation.

Optionally, the first vortex half-wave plate and the second vortex half-wave plate have equal topological charge.

According to the specific embodiment provided by the invention, the invention discloses the following technical effects:

the invention discloses an optical multi-octave nanoscale displacement measurement system, which is characterized in that a first right-angle prism and a second right-angle prism are additionally arranged on the basis of a light source, a polarization beam splitter prism, a first phase change module, a second phase change module and a displacement measurement module, so that multiple reflection of light beams between a first plane reflector (namely a measurement mirror) and a second plane reflector (namely a reference mirror) is realized, compared with the existing displacement measurement based on vector vortex light field interference, the optical path difference between signal light and reference light is increased, and the resolution of the displacement measurement is improved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.

Fig. 1 is a schematic structural diagram of an optical multi-range nanoscale displacement measurement system according to an embodiment of the present invention.

Description of the symbols: the laser comprises a 1-light source, a 2-polarization beam splitter prism, a 3-first right-angle prism, a 4-second right-angle prism, a 5-non-polarization beam splitter prism, a 6-photodetector, a 7-first quarter wave plate, an 8-first plane mirror, a 9-second quarter wave plate, a 10-second plane mirror, an 11-first vortex half wave plate, a 12-dove prism, a 13-second vortex half wave plate, a 14-third right-angle prism, a 15-fourth right-angle prism, a 16-laser beam expander and a 17-third quarter wave plate.

Detailed Description

The technical solutions 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, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention aims to provide an optical multi-range nanoscale displacement measurement system, aims to improve the resolution of displacement measurement, and can be applied to the technical field of displacement measurement.

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.

Fig. 1 is a schematic structural diagram of an optical multi-range nanoscale displacement measurement system according to an embodiment of the present invention. As shown in fig. 1, the optical multi-range nanoscale displacement measurement system in the present embodiment includes: the device comprises a light source 1, a polarization beam splitter prism 2, a first phase change module, a second phase change module, a first right-angle prism 3, a second right-angle prism 4 and a displacement measurement module.

The light source 1 is for emitting laser light.

The polarization beam splitter prism 2 is for splitting the laser light into first transmitted light and first reflected light.

The object to be measured is arranged on the emergent light path of the first phase change module.

The first phase change module is to:

and changing the phase of the first transmission light, and transmitting the first transmission light after the phase change to the object to be measured.

And receiving the first light to be detected reflected by the object to be detected, changing the phase of the first light to be detected to obtain second reflected light, and sending the second reflected light to the polarization beam splitter prism 2.

The second phase change module is arranged on the emergent light path of the first reflected light.

The second phase altering module is to:

the phase and direction of the first reflected light are changed to obtain second transmitted light, and the second transmitted light is sent to the polarization beam splitter prism 2.

The polarization beam splitter prism 2 is further configured to converge the second reflected light and the second transmitted light to obtain a first converged light.

A first right-angle prism 3 disposed on an exit light path of the first converging light; the first right-angle prism 3 is used for reversing the direction of the first converged light to obtain first reversed light.

The polarizing beam splitter prism 2 is also used to split the first flipped light into third transmitted light and third reflected light.

The first phase change module is further to:

and changing the phase of the third reflected light, and transmitting the phase-changed third reflected light to the object to be measured.

And receiving the second light to be measured reflected by the object to be measured, changing the phase of the second light to be measured to obtain fourth transmission light, and sending the fourth transmission light to the polarization beam splitter prism 2.

The second phase altering module is further configured to:

the phase and direction of the third transmitted light are changed to obtain fourth reflected light, and the fourth reflected light is sent to the polarization beam splitter prism 2.

The polarization beam splitter prism 2 is further configured to converge the fourth transmitted light and the fourth reflected light to obtain a second converged light.

The second right-angle prism 4 is arranged on an emergent light path of the second convergent light; the second right-angle prism 4 is used for turning the direction of the second converged light to obtain second turned light.

The polarizing beam splitter prism 2 is also used to split the second flipped light into fifth transmitted light and fifth reflected light.

The displacement measurement module is used for:

and receiving the fifth transmission light and the fifth reflection light, and performing vortex interference on the fifth transmission light and the fifth reflection light to obtain interference vortex rotation.

And calculating the displacement of the object to be measured according to the interference vortex optical rotation in the position moving process of the object to be measured.

As an alternative embodiment, the displacement measuring module comprises: the device comprises a first vortex light generation unit, a second vortex light generation unit, a non-polarization beam splitter prism 5, a photoelectric detector 6 and a calculation unit.

The first vortex light generating unit is arranged on an emergent light path of the fifth reflected light and is used for converting the fifth reflected light into a first vortex rotation.

The second vortex light generating unit is arranged on an emergent light path of the fifth transmission light and is used for converting the fifth transmission light into second vortex rotation.

The non-polarization beam splitter prism 5 is arranged at the junction of the emergent light path of the first vortex rotation and the emergent light path of the second vortex rotation, and the non-polarization beam splitter prism 5 is used for interfering the first vortex rotation and the second vortex rotation to obtain interference vortex rotation.

The photoelectric detector 6 is arranged on an emergent light path of the interference vortex optical rotation, and the photoelectric detector 6 is used for detecting the light intensity of the interference vortex optical rotation in the position moving process of the object to be detected and generating a periodic light intensity change curve.

The calculation unit is connected with the photoelectric detector 6 and used for determining the displacement of the object to be measured according to the light intensity change curve.

Specifically, the calculating unit obtains the periodicity of the light intensity change in the moving process of the object to be measured according to the periodic light intensity change curve, and the displacement of the object to be measured is obtained by multiplying the periodicity by one quarter of the wavelength of the laser.

As an alternative embodiment, the first phase changing module includes: a first quarter-wave plate 7; the first quarter wave plate 7 is arranged on an emergent light path of the first transmitted light and is positioned between the polarization beam splitter prism 2 and the object to be measured.

The first quarter wave plate 7 is used to change the phase of the light passing through the first quarter wave plate 7.

In particular, the first quarter-wave plate 7 is specifically configured to:

the phase of the first transmitted light is changed, and the phase-changed first transmitted light is transmitted to the first plane mirror 8.

And receiving the first light to be detected reflected by the object to be detected, changing the phase of the first light to be detected to obtain second reflected light, and sending the second reflected light to the polarization beam splitter prism 2.

And changing the phase of the third reflected light, and transmitting the phase-changed third reflected light to the object to be measured.

And receiving the second light to be measured reflected by the object to be measured, changing the phase of the second light to be measured to obtain fourth transmission light, and sending the fourth transmission light to the polarization beam splitter prism 2.

Specifically, the optical phase passing through the first quarter-wave plate 7 changes by 90 degrees, the linearly polarized light passes through the first quarter-wave plate 7 to become circularly polarized light, and the circularly polarized light passes through the first quarter-wave plate 7 to become linearly polarized light.

As an optional implementation, the first phase changing module further includes: a first plane mirror 8; the first plane mirror 8 is disposed on the first quarter-wave emitting light path and is located on the surface of the object to be measured.

The first plane mirror 8 is used to reflect the light reaching the first plane mirror 8 to the first quarter wave plate 7.

Specifically, the first plane mirror 8 is specifically configured to: the phase-changed first transmitted light and the phase-changed third reflected light are reflected to the first quarter wave plate 7.

As an alternative embodiment, the second phase changing module includes: a second quarter-wave plate 9 and a second plane mirror 10; the second plane mirror 10 is disposed on the emergent light path of the first reflected light, and the second quarter wave plate is disposed on the emergent light path of the first reflected light and located between the polarization beam splitter prism 2 and the second plane mirror 10.

The second quarter-wave plate 9 is used to change the phase of the light passing through the second quarter-wave plate 9.

The second plane mirror 10 is used for reflecting the light reaching the second plane mirror 10 to the first two-quarter wave plate.

In particular, the second quarter-wave plate 9 is specifically configured to:

the phase of the first reflected light is changed, and the phase-changed first reflected light is sent to the second plane mirror 10.

The phase-changed first reflected light reflected by the second plane mirror 10 is changed to obtain second transmitted light, and the second transmitted light is sent to the polarization beam splitter prism 2.

The phase of the second transmitted light is changed, and the phase-changed second transmitted light is sent to the second plane mirror 10.

And changing the second transmission light after the phase change reflected by the second plane mirror 10 to obtain third transmission light, and sending the third transmission light to the polarization beam splitter prism 2.

The phase of the third transmitted light is changed, and the phase-changed third transmitted light is sent to the second plane mirror 10.

The phase of the phase-changed third transmitted light reflected by the second plane mirror 10 is changed to obtain fourth reflected light, and the fourth reflected light is sent to the polarization beam splitter prism 2.

Specifically, the optical phases of the light passing through the second quarter-wave plate 9 are changed by 90 degrees, the linearly polarized light passes through the second quarter-wave plate 9 to be changed into circularly polarized light, and the circularly polarized light passes through the second quarter-wave plate 9 to be changed into linearly polarized light.

In particular, the second plane mirror 10 is specifically configured to: reflecting the first reflected light and the third transmitted light to the quarter-wave plate.

As an alternative embodiment, the first vortex light generating unit includes: a first vortex half-wave plate 11 and a dove prism 12.

The first vortex half-wave plate 11 is arranged on an emergent light path of the fifth reflected light, and the first vortex half-wave plate 11 is used for converting the fifth reflected light into a third vortex rotation.

The dove prism 12 is disposed on an outgoing light path of the third vortex optical rotation, and the dove prism 12 is configured to reverse a phase of the third vortex optical rotation by 180 degrees to obtain the first vortex optical rotation.

As an alternative embodiment, the second vortex light generating unit includes: a second vortex half-wave plate 13; the second vortex half-wave plate 13 is arranged on an emergent light path of the fifth transmitted light.

The second vortex half-wave plate 13 is used to convert the fifth transmitted light into the second vortex rotation.

As an alternative embodiment, the first vortex light generating unit further includes: a third right-angle prism 14; and the third right-angle prism 14 is arranged on the emergent light path of the fifth reflected light and is positioned between the polarization beam splitter prism 2 and the first vortex half-wave plate 11.

The third rectangular prism 14 is used to change the direction of the fifth reflected light.

Specifically, the third rectangular prism 14 is arranged to make the optical path more orderly, so that the layout of each optical device is more perfect, and the third rectangular prism 14 rotates the transmission direction of the fifth reflected light by 90 degrees. The third right-angle prism 14 can be set according to actual requirements.

The second vortex light generating unit further includes: a third four right-angle prism 15; and a third four-right-angle prism 15 is arranged on an emergent light path of the fifth transmitted light and is positioned between the polarization beam splitter prism 2 and the second vortex half-wave plate 13.

The third four right-angle prism 15 is used to change the direction of the fifth transmitted light.

Specifically, the third four right-angle prism 15 is arranged to make the optical path more neat, so that the layout of each optical device is more perfect, and the third four right-angle prism 15 rotates the transmission direction of the fifth transmission light by 90 degrees. The third four right-angle prism 15 can be set according to actual requirements.

As an optional implementation, the displacement measurement module further includes: a laser beam expander 16; the laser beam expander 16 is arranged on the emergent light path of the interference vortex optical rotation and is positioned between the non-polarization beam splitter prism 5 and the polarization beam splitter prism 2 and the photoelectric detector 6.

The laser beam expander 16 is used for amplifying interference vortex rotation.

In practical application, because the light spot of the laser emitted by the light source 1 is small, the generated interference vortex optical rotation is small in possible size and difficult to collect, and the collection of the interference vortex optical rotation by the photoelectric detector 6 is facilitated through the beam expansion of the laser beam expander 16. The laser beam expander 16 can be set according to actual requirements.

As an alternative embodiment, the topological charge of the first vortex half-wave plate 11 and the second vortex half-wave plate 13 are equal. The topological loads of the first vortex half-wave plate 11 and the second vortex half-wave plate 13 can be adjusted according to actual requirements. When the topological charge of the first vortex half-wave plate 11 and the second vortex half-wave plate 13 is m, the generated topological charge of the first vortex light and the second vortex optical rotation is m, and the number of petals of the image of the subsequent interference vortex optical rotation is 2 m.

As an alternative embodiment, the optical multi-range nanoscale displacement measurement system further comprises: the third quarter wave plate 17 is arranged on the emergent light path of the laser and is positioned between the light source 1 and the polarization beam splitter prism 2; the third quarter-wave plate 17 is used to convert the laser light from linearly polarized light to circularly polarized light.

The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.

The principles and embodiments of the present invention have been described herein using specific examples, which are presented solely to aid in the understanding of the apparatus and its core concepts; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.