Holographic ruler transverse measurement system based on metasurface

Abstract

The invention discloses a holographic ruler transverse measurement system based on a metasurface, which belongs to the technical field of holographic optical measurement and comprises a holographic ruler generation system, an observation system and a holographic ruler. The holographic ruler generation system comprises a holographic ruler shell, an illumination light system and a holographic reticle; the illumination light system and the holographic reticle are arranged in the holographic ruler shell, and an observation window is arranged on the holographic ruler shell; the illumination light system comprises a semiconductor laser, a 1 / 4 wave plate, a beam expander and a reflector; the holographic rulers are virtual focuses with the same focal length, the distance between the virtual focuses is 0.1-1000mm, and the virtual focuses are transversely arranged. The holographic ruler transverse measurement system based on the metasurface is long in measurement endurance time, high in measurement precision, high in measurement performance, small and exquisite in structure, convenient to use and capable of being easily applied to various occasions.

Description

Technical Field

[0001] The present invention relates to the technical field of holographic optical measurement, and in particular to a holographic ruler lateral measurement system based on a metasurface. Background Art

[0002] In the field of measurement in existing technologies, in addition to the earliest direct measurement with a ruler, people have also invented a variety of measurement methods such as laser ranging, ultrasonic ranging, radar ranging, etc. These measurement methods have gotten rid of the problem of direct measurement with a ruler requiring direct contact with the object being measured, and realized "contactless measurement".

[0003] The basic principle of these measurement methods is that a signal generator emits a detection signal, which is reflected back after hitting the surface of the object being measured. The signal is then detected by a signal receiver. The time difference between the signal's transmission and return is calculated, combined with the signal's propagation speed, to ultimately calculate the distance between the object being measured and the measuring instrument. However, this measurement method has many unavoidable drawbacks:

[0004] First, this method of measurement, which relies on reflected signals, places certain demands on the object being measured. When the object cannot reflect signals, such as when encountering the "invisible" materials found on modern fighter jets, "black bodies" in physics, and "virtual images" in optics, the reflective measurement method cannot measure these targets. Secondly, when using reflective measurement, the instrument used for ranging is both a signal receiver and a signal transmitter. Therefore, in many cases, when the measurer needs to secretly measure certain objects, the object being measured will also receive the measurement signal from the ranging instrument. Therefore, the so-called "contactless measurement" only guarantees no physical contact, but does not achieve "perception-free measurement." It cannot completely guarantee that the object being measured will not detect the measurer during measurement.

[0005] To achieve "perception-free measurement," researchers have designed binocular vision systems based on the principles of the human eye. These systems use two cameras to simulate the human eye, photographing the same object. The relative positions of the two cameras and the object being measured are analyzed to determine the distance between the object and the person measuring it. However, this measurement method requires extremely high algorithms and hardware, and has yet to be commercially adopted on a large scale.

[0006] With the emergence and development of holographic technology, humans have achieved the ability to record the phase of a specific light beam using holographic plates. This phase-recording holography has found widespread application in fields such as information encryption, image display, and data storage. In 2011, Professor Capasso's team proposed the principle of controlling the wavefront phase of a light beam using artificial microstructures. This discovery provides a new avenue for the design and fabrication of holographic plates using metasurfaces. The emergence of metasurface holography offers a viable approach to achieving "imperceptible measurement." This led to the design of a metasurface-based holographic ruler lateral measurement system. Summary of the Invention

[0007] The purpose of the present invention is to provide a lateral measurement system of a holographic ruler based on a metasurface. By using the technology of metasurface holography, a virtual ruler is constructed in the virtual image space. Without the need for complex algorithms, "imperceptible measurement" is achieved. The system has a long measurement endurance, high measurement accuracy, strong measurement performance, a compact structure, and is easy to use, and can be easily applied to various occasions.

[0008] To achieve the above-mentioned purpose, the present invention provides a holographic ruler lateral measurement system based on a metasurface, comprising: a holographic ruler generating system, an observation system and a holographic ruler;

[0009] The holographic ruler generating system includes: a holographic ruler housing, an illumination light system, and a holographic graticule;

[0010] The illumination light system and the holographic graticule are arranged inside the holographic ruler housing, and the holographic ruler housing is provided with an observation window; the illumination light system includes a semiconductor laser, a quarter-wave plate, a beam expander, and a reflector; the semiconductor laser, the quarter-wave plate, the beam expander, and the reflector are arranged in sequence inside the holographic ruler housing;

[0011] The holographic reticle is a nanostructure with a PB phase that controls a specific wavelength;

[0012] The observation system is a human eye or a camera system with a zoom function;

[0013] The holographic ruler has virtual focuses with the same focal length, the distance between the virtual focuses is 0.1-1000 mm, and the virtual focuses are arranged in a horizontal arrangement.

[0014] Preferably, the normal direction of the 1 / 4 wave plate is arranged parallel to the direction of the light emitted by the semiconductor laser, so that the parallel linear polarized light with an incident angle of 0° is converted into circularly polarized light; the normal direction of the 1 / 4 wave plate is arranged parallel to the optical axis direction of the beam expander, so that the circularly polarized light is expanded.

[0015] Preferably, the normal direction of the mirror is 15-30 degrees with the light emitted by the semiconductor laser to ensure that the light emitted by the semiconductor laser irradiates the holographic scale.

[0016] Preferably, the mirror is placed in the exit direction of the beam expander, and the deflected circularly polarized parallel light of the beam expander irradiates in a direction parallel to the normal direction of the holographic scale.

[0017] Preferably, the material of the holographic scale is silica glass and hydrogenated amorphous silicon.

[0018] Preferably, the nano microstructure of the holographic scale is an elliptical column structure with a size of half major axis a = 100-300 nm, half minor axis b = 40-100 nm, and height H = 50-200 nm.

[0019] Preferably, the thickness of the holographic scale is 1-3 mm, and the radius of the working area circle of the nano microstructure is 0.05-10 mm.

[0020] Preferably, the holographic scale is composed of artificially designed virtual foci.

[0021] Preferably, the wavelength of the light emitted by the semiconductor laser is 500-700 nm.

[0022] Therefore, the present application adopts the above-mentioned holographic scale transverse measurement system based on a metasurface, and the technical effects are as follows:

[0023] 1) In the present application, the artificially designed metasurface is used as a holographic scale, which can accurately control the wavefront phase of the light beam irradiated thereon according to the PB phase principle, thereby presenting a holographic scale composed of virtual foci in the observation system. The measurement principle of the holographic scale does not depend on the reflection of the measured object, so the present application can measure the size parameters of "invisible materials" and "black bodies" that cannot reflect electromagnetic waves, and the measurement performance under extreme "non-perception" conditions is also greatly superior to existing measurement methods.

[0024] 2) In the present application, the artificially designed metasurface is used as a holographic scale, which accurately controls the wavefront of the light beam according to the PB phase principle. Since each virtual focus of the holographic scale is designed by precise calculation, rather than being "shot" by traditional holography, the use of metasurface technology can make the accuracy of the holographic scale reach the sub-wavelength level, breaking through the focusing limit in physics.

[0025] 3) The present invention concentrates the metasurface diffraction pattern that forms the diffraction graticule in the center of the entire observation window. The remaining area without the diffraction pattern is made of only silica glass. This allows the light from the target to enter the observation system with minimal attenuation when the holographic ruler is measuring the target, greatly improving the transmittance of the holographic ruler and making the observation window brighter.

[0026] 4) The present invention utilizes a precise design of the metasurface diffraction pattern that forms the diffraction graticule, significantly improving its light deflection efficiency. This eliminates the need for high-power lasers to ensure that the observation system can observe a clear and bright holographic scale even in strong ambient light. This significantly reduces laser energy consumption and increases the overall battery life of the holographic scale measurement system.

[0027] 5) The metasurface holographic graticule of the present invention can be prepared using nanoimprinting technology. Compared with traditional holographic graticule preparation methods, this technology has great advantages in terms of preparation speed and production cost when targeting large-scale production needs, and can significantly reduce the production cost of holographic rulers.

[0028] 6) The holographic ruler measurement system of the present invention has a compact structure, is easy to use, and can be easily applied to various occasions.

[0029] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 1 is a schematic diagram of a first embodiment of a holographic ruler lateral measurement system based on a metasurface according to the present invention;

[0031] Figure 2 This is a schematic diagram of the optical path structure of the holographic ruler generating system when measuring the lateral size of an object in Example 1 of a holographic ruler lateral measurement system based on a metasurface of the present invention;

[0032] Figure 3 This is a schematic diagram of the principle of generating an off-axis virtual image in a first embodiment of a holographic ruler lateral measurement system based on a metasurface of the present invention;

[0033] Figure 4 This is the result of using the metasurface microstructure to control the phase of the light beam in the first embodiment of the holographic ruler lateral measurement system based on the metasurface of the present invention;

[0034] Figure 5 is a system schematic diagram of embodiment 2 of the present invention;

[0035] Figure 6 It is a system diagram of embodiment 3 of the present invention.

[0036] Reference numerals

[0037] 1. Semiconductor laser; 2. 1 / 4 wave plate; 3. Beam expander; 4. Reflector; 5. Holographic graticule; 6. Holographic ruler housing; 7. Holographic ruler generation system; 8. Observation system; 9. Holographic ruler; 10. Virtual scale. DETAILED DESCRIPTION

[0038] The technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments.

[0039] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used in the present invention should be the common meanings understood by people with ordinary skills in the field to which the present invention belongs.

[0040] Example 1

[0041] like Figure 1 As shown, the present invention provides a metasurface-based holographic ruler lateral measurement system, aiming to provide an efficient, accurate, and contactless measurement solution. The system primarily consists of three core components: a holographic ruler generation system 7, an observation system 8, and a holographic ruler 9.

[0042] The overall structure of the holographic ruler generating system 7 is as follows Figure 2 As shown, the holographic ruler generation system 7 includes a holographic ruler housing 6, an illumination light system, and a holographic graticule 5. The illumination light system and the holographic graticule 5 are disposed within the holographic ruler housing 6. The holographic graticule 5 has a holographic pattern designed through a metasurface. The holographic graticule 5 adopts a transmissive metasurface design, and its surface is engraved with nanostructures that precisely control the PB phase of a specific wavelength. These structures can achieve a high degree of modulation of the incident light wavefront phase.

[0043] The holographic ruler housing 6 is made of high-strength and lightweight aluminum alloy, and its shape is an irregular pattern. A 50mm×30mm observation window is opened in the middle of the front of the holographic ruler housing 6 for subsequent observation of the holographic ruler 9, which facilitates users to quickly locate the target area and improves the operation convenience of the system.

[0044] The illumination light system consists of a semiconductor laser 1, a quarter wave plate 2, a beam expander 3, and a reflector 4. The semiconductor laser 1 uses a helium-neon semiconductor laser with a wavelength of 632.8 nm, which is in the visible light range that the human eye is more sensitive to, making it easy to observe.

[0045] The normal direction of the quarter-wave plate 2 is set parallel to the direction of the light emitted by the semiconductor laser 1, so that the parallel linear polarized light with an incident angle of 0° is converted into circularly polarized light. At the same time, the normal direction of the quarter-wave plate 2 is set parallel to the optical axis direction of the beam expander 3, so that the circularly polarized light is expanded. Select a beam expander 3 with a magnification of 5 to expand the circularly polarized light to meet the subsequent irradiation requirements.

[0046] A plane mirror is used as the reflector 4, and its normal direction is at an angle of 20° to the light emitted by the red light semiconductor laser 1. It is placed in the emission direction of the beam expander 3 to ensure that the irradiation direction of the circularly polarized parallel light of the beam expander after deflection by the reflector 4 is parallel to the normal direction of the holographic graticule 5, ensuring that the light emitted by the semiconductor laser 1 can accurately irradiate the holographic graticule 5.

[0047] Holographic reticle 5 uses silica glass as its substrate, upon which a nanostructured working area composed of hydrogenated amorphous silicon is fabricated. The nanostructure is an elliptical cylinder with dimensions of semi-major axis a = 200 nm, semi-minor axis b = 60 nm, and height H = 120 nm. Holographic reticle 5 is 2 mm thick, and the radius of the nanostructured working area is 5 mm. Holographic reticle 5 carries the phase information of the holographic scale and is used to construct the holographic scale 9 in the virtual image space.

[0048] The holographic ruler 9 has virtual foci with the same focal length, the distance between the virtual foci is 500 mm, and they are arranged in a horizontal arrangement, as shown in FIG. Figure 1 As shown, this provides the necessary foundation for subsequent measurement of the object's lateral dimensions. The holographic ruler 9 is composed of artificially designed virtual focal points, generated using metasurface technology, which form stable virtual reference points in space. By controlling the arrangement of multiple virtual focal points, the "holographic ruler 9" can be constructed.

[0049] Observation system 8 supports both human eye and zoom camera modes to meet the needs of different scenarios. Furthermore, a built-in ray path inversion algorithm is included in observation system 8, enabling accurate reconstruction of the position of the virtual scale 10 after receiving the modulated light beam. With observation system 8, users can clearly see the holographic scale 9, formed by the virtual focus, and adjust the viewing angle or magnification as needed to obtain more accurate measurement results.

[0050] Compared to traditional physical rulers, the metasurface-based holographic ruler 9 is wear-free and drift-free, while significantly improving its resolution and measurement range. Furthermore, because the position of the virtual focus can be dynamically adjusted through software programming, the system is particularly suitable for high-precision measurement tasks in complex environments.

[0051] In this embodiment, the holographic graticule 5 is a metasurface structure. When circularly polarized light is irradiated onto the nanostructures on it, its phase changes according to the rotation direction of the nanostructures. The phase change caused by this reason is called "PB phase". When we precisely control the rotation direction of each nanostructure, we can use the PB phase generated to adjust the output light to the desired style of the holographic ruler 9. The relationship between the rotation direction of the nanostructure and the PB phase of the light beam is shown as follows: Figure 4 shown.

[0052] In this embodiment, the generation principle of the holographic ruler 9 is as follows: when the incident leveling light is wavefront modulated by the holographic graticule 5, its transmission direction will change as follows: Figure 3 As shown in the changes, when the observation system 8 receives the modulated light beam, the observation system 8 will reversely deduce the light path, so that a virtual scale 10 appears in the system. By controlling the arrangement of multiple virtual scales 10, the "holographic ruler 9" can be realized.

[0053] In this embodiment, the optical path is: semiconductor laser 1 → 1 / 4 wave plate 2 (linear polarization to circular polarization) → beam expander 3 → reflector 4 (15-30° deflection) → metasurface holographic graticule 5 for wavefront modulation.

[0054] The output light of the semiconductor laser 1 is first irradiated onto the 1 / 4 wave plate 2. The normal direction of the 1 / 4 wave plate 2 is placed parallel to the direction of the light source. The output light of the semiconductor laser 1 will become circularly polarized light after passing through the 1 / 4 wave plate 2. The circularly polarized light is expanded by the beam expander 3. The optical axis direction of the beam expander 3 is parallel to the incident direction of the light beam. After expansion by the beam expander, the output light of the semiconductor laser 1 will become expanded flat-top circularly polarized light. After passing through the reflector 4, the circularly polarized light with an incident angle of 0° is reflected and irradiated onto the metasurface holographic graticule 5 at a certain angle to the incident light.

[0055] The metasurface holographic graticule 5 modulates the wavefront phase of the incident circularly polarized light. The modulated light beam enters the observation system 8. When the observation system 8 is used to observe in the observation direction, a holographic scale 9 composed of several virtual focal points can be observed on the same focal plane at a certain distance from the holographic scale generating system 7. When the observation system 8 observes through the observation window, when the holographic scale 9 and the measured object coincide with each other (are in the same focal plane), the lateral size information of the measured object can be directly read according to the preset graduation value of the holographic scale lateral measurement system.

[0056] The effects of the present invention are as follows:

[0057] High-precision measurement: The holographic pattern generated by the present invention using metasurface technology has extremely high spatial resolution and can achieve sub-micron lateral dimension measurement, significantly exceeding the accuracy limit of traditional measurement tools.

[0058] Non-contact operation: Since the holographic ruler 9 is composed of virtual focal points, the entire measurement process does not require direct contact with the object being measured, avoiding errors or damage caused by contact. It is particularly suitable for measuring fragile materials or precision components.

[0059] Dynamic adjustability: By changing the nanostructure parameters on the holographic graticule 5 or adjusting the output characteristics of the illumination light system, the virtual focus distribution of the holographic ruler 9 can be changed in real time to adapt to different measurement requirements.

[0060] Strong anti-interference ability: The metasurface design gives the holographic ruler 9 excellent anti-environmental interference ability, and it can still maintain a stable working state under strong light, vibration or other adverse conditions.

[0061] Wide range of application fields: The system is not only suitable for precision measurement in laboratory environments, but can also be widely used in industrial production, aerospace, medical diagnosis and other fields.

[0062] Example 2

[0063] Different from the first embodiment, the holographic ruler 9 in this embodiment has focal points with different focal lengths, and the focal points are arranged obliquely, such as Figure 5 As shown, it provides the necessary basis for measuring the depth dimension of an object.

[0064] The depth measurement operation is as follows:

[0065] The semiconductor laser 1 is turned on to start the illumination light system. The light passes through the 1 / 4 wave plate 2, the beam expander 3 and the reflector 4 in sequence and then irradiates the holographic graticule 5.

[0066] Since the holographic graticule 5 carries the phase information of the holographic scale, the wavefront phase of the light beam incident thereon is precisely controlled according to the PB phase principle, and a holographic scale 9 consisting of virtual focuses appears in the observation system 8.

[0067] The object to be measured is placed at a suitable position in front of the holographic ruler 9 , and the relative position relationship between the holographic ruler 9 and the object is observed through the observation system 8 .

[0068] When a virtual focus of the holographic ruler 9 coincides with the object being measured or is in the same focal plane as the object being measured, the depth dimension information of the object being measured can be directly read according to the preset graduation value of the holographic ruler depth measurement system without the need for complex algorithms, realizing "non-sensing measurement".

[0069] In the actual measurement process, the depth of various objects with different materials and shapes is measured, including objects coated with special materials (similar to "stealth materials") and black light-absorbing objects (similar to "black bodies"). The measurement results show that the system can accurately measure the depth size parameters of these objects, with a measurement accuracy of sub-wavelength level, and the measurement result error is within ±0.1 mm, verifying the advantages of the system in measuring special material objects and the high-precision characteristics.

[0070] At the same time, under the condition of continuous work for 8 hours, the system can still run stably, and the holographic ruler 9 in the observation system 8 is imaged clearly and brightly, indicating that the system has a long measurement endurance time. Moreover, the system is small and light, and can be easily used in different narrow spaces and complex environments, fully embodying its characteristics of small structure and easy use.

[0071] Example Three

[0072] Different from example one, in this embodiment, the holographic ruler 9 is a focal point with the same focal length, and the arrangement mode between the focal points is circular arrangement, as shown in Figure 6 which provides the necessary basis for measuring the angular size of the object.

[0073] The specific operation of angular measurement is as follows:

[0074] Turn on the system and start the red semiconductor laser 1 to emit light. The light passes through the 1 / 4 wave plate 2, the beam expander 3 and the mirror 4 in turn, and then irradiates onto the holographic scale plate 5.

[0075] According to the PB phase principle, the holographic scale plate 5 accurately controls the wavefront phase of the light beam irradiated onto it, and presents the holographic ruler 9 composed of virtual focal points in the observation system 8.

[0076] Place the object whose angle needs to be measured in a suitable position, and observe the relative position relationship between the holographic ruler 9 and the measured object through the observation system 8. Without complex algorithms, the angular size parameter of the measured object can be directly obtained from the holographic ruler 9. For example, to measure the angle of an arc-shaped metal part, place the part in front of the holographic ruler 9, and the corresponding holographic ruler scale of the part angle can be directly read through the observation system 8.

[0077] Measurement effect verification:

[0078] A "stealth material" sample is selected for measurement. Traditional measurement methods cannot measure the size parameters of the sample because they cannot obtain the reflection signal. However, based on the metasurface holographic technology, the system does not rely on the reflection of the measured object and successfully measures the angular size of the "stealth material" sample, verifying the advantages of the system in measuring special materials.

[0079] A high-precision standard arc mold was used as the measured object, and the measurement results of this system were compared with the actual dimensions of the standard mold. The measurement error was at the sub-wavelength level, proving that the measurement accuracy of this system has reached a high level and has broken through the physical focusing limit.

[0080] Verification of transmittance and observation effect: The same object was measured under different lighting environments. Since the system concentrates the metasurface diffraction pattern in the center of the observation window, and only silica glass exists in the rest of the area, the light from the target can enter the observation system 8 with minimal attenuation. The observation window is bright and clear. Even in strong ambient light, the holographic ruler 9 can still be clearly observed through the observation system 8 of this system. No high-power laser is required, which saves energy consumption and improves the system's battery life.

[0081] At the same time, angle measurements of various objects were carried out in different occasions such as laboratories, industrial production workshops, and outdoors. The system has a compact structure and is easy to operate, and can successfully complete the measurement tasks, verifying its applicability in various occasions.

[0082] Therefore, the present invention adopts the above-mentioned metasurface-based holographic ruler lateral measurement system, which has a simple structure and uses metasurface holographic technology to construct a virtual ruler in the virtual image space. Without the need for complex algorithms, it can achieve "non-perceptual measurement" and has a long measurement endurance, micron-level measurement accuracy, strong measurement performance, compact structure, and easy use, and can be easily applied to various occasions.

[0083] It is worth noting that the contents not elaborated in detail in the present invention are all prior art and are well known to those skilled in the art.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A holographic ruler lateral measurement system based on a metasurface, characterized in that: include: Holographic ruler generation system, observation system and holographic ruler; The holographic ruler generating system includes: a holographic ruler housing, an illumination light system, and a holographic graticule; The illumination light system and the holographic graticule are arranged inside the holographic ruler housing, and the holographic ruler housing is provided with an observation window; the illumination light system includes a semiconductor laser, a quarter-wave plate, a beam expander, and a reflector; the semiconductor laser, the quarter-wave plate, the beam expander, and the reflector are arranged in sequence inside the holographic ruler housing; The holographic reticle is a nanostructure with a PB phase that controls a specific wavelength; The observation system is a human eye or a camera system with a zoom function; The holographic ruler has virtual focuses with the same focal length, the distance between the virtual focuses is 0.1-1000 mm, and the virtual focuses are arranged in a horizontal arrangement.

2. The metasurface-based holographic ruler lateral measurement system according to claim 1, characterized in that: The normal direction of the 1 / 4 wave plate is parallel to the direction of the light emitted by the semiconductor laser; the normal direction of the 1 / 4 wave plate is parallel to the optical axis direction of the beam expander.

3. The metasurface-based holographic ruler lateral measurement system according to claim 2, characterized in that: The angle between the normal direction of the reflector and the light emitted by the semiconductor laser is 15-30°, and the reflector is a plane mirror; The reflector is placed in the emitting direction of the beam expander, and the irradiation direction of the circularly polarized parallel light of the beam expander after being deflected by the reflector is arranged parallel to the normal direction of the holographic graticule.

4. The metasurface-based holographic ruler lateral measurement system according to claim 3, characterized in that: The materials of the holographic grating plate are silicon dioxide glass and hydrogenated amorphous silicon.

5. The metasurface-based holographic ruler lateral measurement system according to claim 4, characterized in that: The holographic reticle nanostructure is an elliptical column structure with the following dimensions: semi-major axis a=100-300 nm, semi-minor axis b=40-100 nm, and height H=50-200 nm.

6. The metasurface-based holographic ruler lateral measurement system according to claim 5, characterized in that: The thickness of the holographic grating plate is 1-3 mm, and the radius of the nano-microstructure working area circle is 0.05-10 mm.

7. The metasurface-based holographic ruler lateral measurement system according to claim 6, characterized in that: The holographic ruler is composed of artificially designed virtual focuses.

8. The metasurface-based holographic ruler lateral measurement system according to claim 1, characterized in that: The wavelength of the light emitted by the semiconductor laser is 500-700 nm.

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