Light detection sensor and light projection device and optical module thereof

Abstract

The invention relates to the technical field of light detection, in particular to a light detection sensor and a light projection device and an optical module thereof, the light projection device comprises an illumination optical system, a light modulation element and a projection optical system, and the illumination optical system is configured to emit light advancing along a first preset light path; the light modulation element is configured to receive light emitted by the illumination optical system and modulate the light to generate modulated light, and the modulated light travels along a second preset light path; the projection optical system is configured to receive the modulated light and guide the modulated light to advance along a second preset light path; the projection optical system comprises a plurality of lenses, and optical axes of partial lenses in the plurality of lenses are offset by a preset offset amount relative to a main optical axis of the projection optical system. According to the invention, under the condition that a relatively small Samm angle is adopted, the misalignment amount is preset for a part of lenses in the plurality of lenses, so that the miniaturization requirement of the sensor can be met, and the light energy transmission efficiency can be improved.

Description

Technical Field

[0001] The present invention relates to the field of light detection technology, and in particular to a light detection sensor and a light projection device and an optical module thereof. Background Art

[0002] With the continuous development of industry, the degree of industrial automation production is getting higher and higher, and the requirements for the quantity and quality of parts are also getting higher and higher. Therefore, it is urgent to solve the problem of precise and rapid measurement of the microstructure of the surface of parts. Traditional manual visual inspection has the disadvantages of low inspection efficiency, high labor intensity, and the inspection accuracy is affected by subjective factors of personnel. It is not suitable for automated mass production lines. As a high-precision inspection method at present, optics has been active in the field of automated inspection.

[0003] At present, the inspection of parts requires not only the detection of their two-dimensional texture information, but also the detection of their height information, so three-dimensional inspection technology is increasingly widely used. One type of three-dimensional inspection technology is a three-dimensional reconstruction technology based on the triangulation principle and a structured light 3D camera. This type of 3D sensor usually uses one or two projectors combined with a camera. The projector and the main optical axis of the camera form a certain angle. The projector projects structured light on the object to be measured, and the camera captures the structured light image of the object. The moiré pattern is used to analyze the microscopic surface information, and then three-dimensional reconstruction is performed to obtain the height image of the object to reconstruct the surface morphology of the object.

[0004] In order to obtain an accurate height image, the light spot projected onto the object to be measured is required to meet certain clarity and uniformity. Therefore, the object plane where the platform carrying the object to be measured is located, the main plane of the optical system, and the projection image plane where the structured light modulation element is located should theoretically comply with the Scheimpflug theorem. However, with the miniaturization of 3D sensors, it is found that when the projection optical system works at a low magnification, a large Scheimpflug angle will cause positional interference between optical elements, and a large Scheimpflug angle will also reduce the efficiency of light energy transmission. Summary of the invention

[0005] The main technical problem solved by the present invention is to provide a light detection sensor and a light projection device and an optical module thereof, so as to meet the miniaturization requirements of the sensor and improve the light energy transmission efficiency.

[0006] According to a first aspect, an embodiment provides a light projection device, comprising:

[0007] an illumination optical system configured to emit light having at least one wavelength and cause the emitted light to travel along a first preset optical path;

[0008] a light modulation element configured to receive light emitted by the illumination optical system, modulate the light, and generate modulated light, wherein the modulated light travels along a second preset optical path after being emitted from the light modulation element, and the modulated light includes uniform light and / or structured light of at least one wavelength;

[0009] A projection optical system is configured to receive the modulated light, guide the modulated light along a second preset optical path, and project the modulated light onto the object to be measured in a direction that forms a first preset angle α with an object plane carrying the object to be measured; the projection optical system includes a plurality of lenses, and the optical axes of some of the lenses in the plurality of lenses are offset by a preset misalignment amount relative to the main optical axis of the projection optical system.

[0010] In some embodiments, the projection optical system comprises:

[0011] A front lens group is arranged on a second preset optical path, receives the incident modulated light, and amplifies and eliminates aberrations of the modulated light;

[0012] A rear lens group, which is arranged on a second preset optical path and is located downstream of the front lens group and is independently arranged relative to the front lens group, and is used to converge and eliminate aberrations of the modulated light, and project the modulated light onto the object to be measured in a direction that forms a first preset angle α with the object plane carrying the object to be measured;

[0013] The optical axis of the rear mirror group coincides with the main optical axis of the projection optical system, the optical axis of the front mirror group is parallel to the main optical axis, and the optical axes of at least a part of the lenses in the front mirror group are offset by a preset misalignment amount relative to the main optical axis; or the optical axis of the front mirror group coincides with the main optical axis of the projection optical system, the optical axis of the rear mirror group is parallel to the main optical axis, and the optical axes of at least a part of the lenses in the rear mirror group are offset by a preset misalignment amount relative to the main optical axis.

[0014] In some embodiments, the optical axes of at least a portion or all of the lenses in the front lens group are offset by a preset misalignment amount in a direction perpendicular to the main optical axis of the projection optical system in a positive or negative direction relative to the main optical axis; or

[0015] The optical axes of at least a part or all of the lenses in the rear mirror group are offset by a preset misalignment amount relative to the main optical axis in a direction perpendicular to the main optical axis of the projection optical system in a positive or negative direction.

[0016] In some embodiments, the preset misalignment amount ΔX is: 0.05 mm≤ΔX≤0.5 mm.

[0017] In some embodiments, the plane where the light modulation element is located and the main optical axis of the second preset optical path have a second preset angle β1, and the second preset angle β1 is an acute angle and is greater than the angle β determined based on the following formula:

[0018] tan[π / 2-α] / tan[π / 2-β]=M

[0019] Among them, angle α is a first preset angle, M is the magnification of the set point on the optical axis, and angle β is the angle between the main optical axis of the light modulation element and the second preset optical path determined when the image plane, the main plane of the projection optical system and the object plane carrying the object to be measured conform to Scham's law.

[0020] In some embodiments, the value of the first preset angle α satisfies: 60°≤α≤70°,

[0021] The value of the second preset angle β1 satisfies: 5°≤90°-β1≤10°.

[0022] In some embodiments, the rear mirror group includes a first negative lens and a first positive lens sequentially arranged along the traveling direction of the modulated light, and the front mirror group includes a second positive lens and a second negative lens sequentially arranged along the traveling direction of the modulated light.

[0023] In some embodiments, the first positive lens and the first negative lens are bonded together to form a first bonded lens, and the second negative lens and the second positive lens are bonded together to form a second bonded lens.

[0024] In some embodiments, the front lens group also includes a third positive lens and a fourth positive lens, the third positive lens is close to the second positive lens and is arranged upstream of the second positive lens along the second preset optical path, and the fourth positive lens is close to the third positive lens and is arranged upstream of the third positive lens along the second preset optical path.

[0025] In some embodiments, an aperture is further included, wherein the aperture is disposed between the rear lens group and the front lens group, and an optical axis of the aperture overlaps with an optical axis of the rear lens group.

[0026] In some embodiments, the focal length f of the rear mirror assembly is b The focal length f of the front lens group d The ratio is: 0.5≤f d / f b ≤1.2.

[0027] In some embodiments, based on the preset misalignment amount, the thickness, curvature and medium refractive index of each lens in the projection optical system are configured so that the optical path of light in the positive direction of the main optical axis of the projection optical system is shorter than the optical path of light in a symmetrical position in the negative direction of the main optical axis of the projection optical system.

[0028] In some embodiments, the light modulation element is a digital micromirror device or a reflective liquid crystal element.

[0029] In some embodiments, the projection optical system further includes a first packaging structure, wherein the first packaging structure packages the front lens group and the rear lens group therein, so that the relative positions of the front lens group and the rear lens group are fixed and maintained.

[0030] According to the second aspect, an embodiment provides an optical module, including:

[0031] The front lens group is used to receive incident light, amplify the incident light and eliminate aberration;

[0032] a rear mirror group, which is arranged downstream of the front mirror group along the optical path and is independently arranged relative to the front mirror group, and is used to converge and eliminate aberrations of light emitted by the front mirror group, and project the light onto the object to be measured in a direction that forms a first preset angle with the object plane carrying the object to be measured; the optical axis of the rear mirror group coincides with the main optical axis of the optical module, the optical axis of the front mirror group is parallel to the main optical axis, and the optical axis of at least a part of the lenses in the front mirror group is offset by a preset misalignment amount relative to the main optical axis;

[0033] A first packaging structure, wherein the first packaging structure packages the front lens group and the rear lens group therein, so that the relative positions of the front lens group and the rear lens group are fixed and maintained.

[0034] In some embodiments, the optical axes of at least a portion or all of the lenses in the front lens group are positively or negatively offset by a preset misalignment amount relative to the main optical axis of the projection optical system in a direction perpendicular to the main optical axis of the projection optical system.

[0035] In some embodiments, the thickness, curvature and medium refractive index of each lens in the front lens group are configured so that the optical path of light in the positive direction of the main optical axis of the optical module after passing through the front lens group is shorter than the optical path of light in a symmetrical position in the negative direction of the main optical axis of the optical module after passing through the front lens group.

[0036] According to a third aspect, an embodiment provides an optical module, including:

[0037] The front lens group is used to receive incident light, amplify the incident light and eliminate aberration;

[0038] a rear mirror group, which is arranged downstream of the front mirror group along the optical path and is independently arranged relative to the front mirror group, and is used to converge and eliminate aberrations of light emitted by the front mirror group, and project the light onto the object to be measured in a direction that forms a first preset angle with the object plane carrying the object to be measured; the optical axis of the front mirror group coincides with the main optical axis of the optical module, the optical axis of the rear mirror group is parallel to the main optical axis, and the optical axis of at least a part of the lenses in the rear mirror group is offset by a preset misalignment amount relative to the main optical axis;

[0039] A first packaging structure, wherein the first packaging structure packages the front lens group and the rear lens group therein, so that the relative positions of the front lens group and the rear lens group are fixed and maintained.

[0040] In some embodiments, the optical axes of at least a portion or all of the lenses in the rear mirror group are positively or negatively offset by a preset misalignment amount relative to the main optical axis along a direction perpendicular to the main optical axis of the projection optical system.

[0041] In some embodiments, the thickness, curvature and medium refractive index of each lens in the rear mirror group are configured so that the optical path of light in the positive direction of the main optical axis of the optical module after passing through the rear mirror group is shorter than the optical path of light in a symmetrical position in the negative direction of the main optical axis of the optical module after passing through the rear mirror group.

[0042] In some embodiments, the preset misalignment amount ΔX is: 0.05 mm≤ΔX≤0.5 mm.

[0043] According to a fourth aspect, an embodiment provides a light detection sensor, comprising:

[0044] A light projection device as described in any of the above embodiments;

[0045] An image acquisition device, the image acquisition device includes a light receiving system and an imaging system, the optical axis of the light receiving system is perpendicular to the object plane used to carry the object to be measured, receives diffusely reflected modulated light within at least a partial angle formed by diffuse reflection of the object to be measured after being irradiated by the modulated light, and guides the diffusely reflected modulated light to the imaging system, the imaging system generates height image data reflecting height information of the object to be measured and / or texture image data reflecting texture information of the object to be measured based on the diffusely reflected modulated light.

[0046] Normally, the optical axes of multiple lenses in a projection optical system coincide with the main optical axis, and the main light of the field of view on the optical axis does not deviate from the main optical axis when passing through the center of curvature of each lens. The present application reasonably matches the misalignment compensation of the lenses in the projection optical system, presets a certain misalignment amount for a part of the multiple lenses, so that the center of curvature of this part of the lenses deviates from the main optical axis of the projection optical system, and when the light beam propagates in the lens with the misalignment compensation, the field of view point originally symmetrical about the optical axis will produce a shortened or increased optical path difference, and the optical path difference generated by the optical axis offset can compensate for the optical path difference of the field of view points in the positive and negative directions of the main optical axis of the actual image plane of the light modulator relative to the Gaussian image plane, so that the light modulator is transformed from a Gaussian image plane with a larger Sham angle that satisfies the Sham theorem to an actual image plane with a smaller Sham angle, thereby realizing that when the projection optical system works in a low magnification state, the light modulator can be set to a smaller Sham angle, thereby avoiding the position interference problem between the light modulator and other optical elements in the light detection sensor, so as to realize the miniaturization of the light detection sensor. And because the light modulator has a small Sham angle, it can also reduce light energy transmission loss and improve the light energy transmission efficiency of the light detection sensor. At the same time, when the light modulator has a small Sham angle, the optical path is compensated by lens misalignment, so that the modulated light projected onto the object plane by the projection optical system can still meet the requirements of high definition and high uniformity. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 This is a schematic diagram of the structure of a light detection sensor in one embodiment of the present application;

[0048] Figure 2 for Figure 1 A schematic diagram of the structure of the light projection device and the image acquisition device;

[0049] Figure 3 for Figure 2 Schematic diagram of the structure of the RTIR prism (compound prism) and the light modulation element;

[0050] Figure 4 Schematic diagram of an optical system that complies with Scham's theorem;

[0051] Figure 5 for Figure 2 Schematic diagram of the optical system of the middle object plane, RTIR prism and light modulation element;

[0052] Figure 6 for Figure 5 Comparison diagram between the actual image plane and the Gaussian image plane of the optical system on the light modulation element;

[0053] Figure 7 It is a structural schematic diagram when the optical axis of the lens group is offset from the main optical axis of the optical system;

[0054] Figure 8 for Figure 7 Comparison table of optical path changes of ±1 axis of the main optical axis of the optical system in the lens group;

[0055] Fig. 9 for Figure 2 A schematic diagram of the cross-sectional structure of the projection optical system;

[0056] Fig.10 for Fig. 9 Comparison diagram of the optical principle of the projection optical system before and after the optical axis of the front lens group is offset;

[0057] Fig.11 for Fig. 9 Parameter table of each lens of the medium light projection device;

[0058] Fig.12 The modulation transfer function (MTF) curves of different sampling points on the surface of the light modulation element when neither misalignment compensation is performed on the projection optical system nor the tilt angle (8.6°) of the light modulation element is changed;

[0059] Fig.13 The modulation transfer function (MTF) curves of different sampling points on the surface of the light modulation element when the projection optical system is not compensated for misalignment but the tilt angle of the light modulation element is changed (5°);

[0060] Fig.14 The modulation transfer function (MTF) curves of different sampling points on the surface of the light modulator when the tilt angle (5°) of the light modulator is changed in order to compensate for the misalignment of the projection optical system;

[0061] Fig.15 In order to compensate for the misalignment of the projection optical system, the relative illumination curve is also changed when the tilt angle (5°) of the light modulation element is changed.

[0062] Reference numerals:

[0063] 1-light detection sensor; 11-light projection device; 11a-illumination optical system; 11b-projection optical system; 11b`-moved projection optical system; 111-light source; 112-shaping mirror group; 113-reflector; 114-prism; 115-light modulation element; 115`-mirror light modulation element; 12-image acquisition device; 13-calculation processing device; 14-controller; 15-memory; 16-communication unit; 17-input and output device;

[0064] 21-front lens group; 211-second positive lens; 212-second negative lens; 213-third positive lens; 214-fourth positive lens; 22-rear lens group; 221-first negative lens; 222-first positive lens; 23-first packaging structure; 24-aperture. DETAILED DESCRIPTION

[0065] The present invention is further described in detail below by specific embodiments in conjunction with the accompanying drawings. Wherein similar elements in different embodiments adopt associated similar element numbers. In the following embodiments, many detailed descriptions are for making the present application better understood. However, those skilled in the art can easily recognize that some features can be omitted in different situations, or can be replaced by other elements, materials, methods. In some cases, some operations related to the present application are not shown or described in the specification, this is to avoid the core part of the present application being overwhelmed by too much description, and for those skilled in the art, it is not necessary to describe these related operations in detail, and they can fully understand the related operations according to the description in the specification and the general technical knowledge in the art.

[0066] In addition, the features, operations or characteristics described in the specification can be combined in any appropriate manner to form various implementations. At the same time, the steps or actions in the method description can also be interchanged or adjusted in a manner that is obvious to those skilled in the art. Therefore, the various sequences in the specification and the drawings are only for the purpose of clearly describing a certain embodiment and are not meant to be a required sequence, unless otherwise specified that a certain sequence must be followed.

[0067] The serial numbers of the components in this document, such as "first", "second", etc., are only used to distinguish the objects described and do not have any order or technical meaning. The "connection" and "coupling" mentioned in this application, unless otherwise specified, include direct and indirect connections (couplings).

[0068] like Figure 1 As shown, the light detection sensor 1 includes at least one light projection device 11, an image acquisition device 12, a processing device 13 and a controller 14. In some embodiments, the light detection sensor 1 also includes one or more of a memory 15, a communication unit 16 and an input / output device 17, which are described below respectively.

[0069] The light projection device 11 is used to project modulated light onto the object to be detected (e.g., the object to be detected S1 shown in the figure). The modulated light can be, for example, uniform light of one wavelength (e.g., red light), or uniform light mixed with multiple wavelengths (e.g., white light), or structured light with a preset pattern. The structured light can be, for example, a stripe image in digital form. The stripe image can be preset by the user and transmitted to the light projection device 11 through the controller 14 for projection. The stripe image here includes a phase-shifted image and / or a Gray code image. For example, there can be one or two light projection devices 11. In one embodiment, the light projection device 11 projects the modulated light onto the object to be detected S1 in an inclined manner, so that there is a preset acute angle α between the optical axis and the object plane OP (i.e., the platform used to carry the object to be detected in the actual application scenario).

[0070] The image acquisition device 12 is used to collect the diffusely reflected modulated light formed by the modulated light projected by the light projection device 11 after diffuse reflection by the object to be detected S1. In one embodiment, the image acquisition device includes a light receiving system and an imaging system. The light receiving system can be at least one set of lenses. The optical axis of the light receiving system is perpendicular to the object plane used to carry the object to be detected. The object to be detected generates diffuse reflection distributed in a spatial angle after being irradiated by the modulated light. The light receiving system receives the diffusely reflected modulated light within at least a part of the angle and guides the diffusely reflected modulated light to the imaging system. The imaging system includes other imaging elements such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS) image sensor. The imaging system generates a measurement image based on the diffusely reflected modulated light at a part of the spatial angle. The measurement image can be height image data reflecting the height information of the object to be detected and / or texture image data reflecting the texture information of the object to be detected. In the measurement space, there is a certain angle between the incident light of the image acquisition device 12 and the outgoing light of the light projection device 11, so that the image acquisition device 12 can capture the deformation pattern of the stripe image on the surface of the object to be detected.

[0071] The processing device 13 is connected to the image acquisition device 12, and is used to obtain the measurement image, and process the measurement image using a preset algorithm to obtain the height information and / or texture information of the object S1 to be detected. The algorithm used by the processing device 13 to process the measurement image can adopt existing technical means or future technical means, as long as the height information and / or texture information of the object S1 to be detected is obtained.

[0072] The controller 14 is connected to the light projection device 11 and the image acquisition device 12 respectively, and is used to control the actions of the two. The controller 14 controls the light projection device 11 to emit light and generate modulated light according to the parameters and / or structured light patterns preset by the user, and projects the modulated light onto the object plane OP to illuminate the object S1 to be measured. When there are two sets of light projection devices 11 and the modulated light emitted between the two sets has a certain timing sequence, the controller 14 also controls the actions of the two sets of light projection devices 11 according to a certain timing relationship. The controller 14 also controls the image acquisition device 12 to capture the image of the object S1 after being irradiated with modulated light according to the imaging parameters preset by the user. When there is a certain timing between the shooting action of the image acquisition device 12 and the light projection device 11, for example, the light projection device 11 first emits uniform light, and the image acquisition device 12 captures the image of the object S1 after being irradiated with uniform light, and then the light projection device 11 emits structured light, and the image acquisition device 12 captures the image of the object S1 after being irradiated with structured light, the controller 14 also controls the actions of the light projection device 11 and the image acquisition device 12 according to the shooting timing preset by the user.

[0073] In some embodiments, the controller 14 is also connected to the operation processing device 13, and controls the operation processing device 13 to perform operation and processing on the measurement image generated by the image acquisition device 12, and can also control the operation processing device 13 to perform operation and processing on the measurement image generated by the image acquisition device 12 according to the user's settings. In some embodiments, the operation processing device 13 can automatically perform operation and processing after the measurement image generated by the image acquisition device 12. In some embodiments, the operation processing device 13 can control the measurement image data generated by the image acquisition device 12 to be stored in the memory 15, and the controller 14 can control the operation processing device 13 to read the data from the memory 15 for operation and processing according to the user's input or settings.

[0074] The memory 15 is connected to the processing device 13 and the controller 14 respectively, and is used to store the measured image data so that the controller 14 can read the measured image data (such as texture image data and / or height image data) at any time. The memory 15 is also connected to the communication unit 16, and is used to store the information received by the communication unit 16, or send the stored information through the communication unit 16.

[0075] The communication unit 16 is connected to the controller 14 and the memory 15. In a specific embodiment, the communication unit 16 adopts the RS232 communication protocol, USB communication protocol, Bluetooth communication protocol, and WIFI communication protocol. The measurement image data processed by the operation processing device 13 and the data or information stored in the memory 15 can be sent to the host computer according to the protocol format, and the setting instructions and information sent by the host computer can be received according to the protocol format, and transmitted to the controller 14 and / or the memory 15.

[0076] In some embodiments, the light detection sensor 1 further includes an input-output device 17, which is connected to the controller 14 and is used to set and / or display the measurement parameters, measurement process, and measurement results. The input-output device 17 can implement the input function of instructions, parameters, settings, and / or information through a keyboard, button, key, soft key, voice, gesture, etc., and can implement the display function through any type of display. Preferably, a display with a touch function can be used to facilitate human-computer interaction between the user and the controller 14.

[0077] In the embodiment of the present invention, the light projection device 11 includes an illumination optical system 11a, a light modulation element 115 and a projection optical system 11b. Figure 2 As shown, each part is described in detail below.

[0078] The illumination optical system 11a is configured to emit light having at least one wavelength and to make the emitted light travel along a first preset optical path. In one embodiment, the illumination optical system 11a includes a light source 111, a shaping lens group 112, a reflector 113 and a prism 114. One or more light sources 111 may be provided, and each light source 111 emits light of one wavelength. When only one light source 111 is controlled to emit light, the light emitted by the illumination optical system 11a is monochromatic light. When multiple light sources 111 emit light of multiple wavelengths, the light emitted by the illumination optical system 11a is mixed light. The shaping lens group 112 is configured to be arranged on the optical path, and is used to collect the light emitted by the light source 111, converge and shape the divergent light, and form a convergent light beam or a parallel light beam for emission. The reflector 113 is arranged downstream of the shaping lens group 112 along the optical path, and reflects the light emitted by the shaping lens group 112 to the prism 114. In some embodiments, the reflector 113 may not be provided, but the light emitted by the shaping lens group 112 may be directly projected onto the first side surface m1 of the prism 114, or a lens with other functions may be used to replace the shaping lens group 112, or a lens with other functions may be provided upstream (close to the light source 111) or downstream (far from the light source 111) of the shaping lens group 112 along the light path. Figure 3 As shown, the prism 114 can be an RTIR prism, that is, the RTIR prism includes a first side m1, a middle interface m2 and a second side m3, the interface m2 transmits the light incident from the first side m1, and totally reflects the light incident from the second side m3, after the light beam is incident on the RTIR prism, it is transmitted and refracted by the RTIR prism, and the light beam is projected onto the light modulation element 115. The light path from the light source 111 to the prism 114 is called a first preset light path, and the first preset light path can be a straight line, or it can become a curved light path after passing through the reflector 113 and / or the prism 14.

[0079] The light modulator 115 is arranged on the first preset optical path, and may be a digital micromirror device DMD or a reflective liquid crystal element LCOS, which is configured to receive light transmitted through the prism 114, modulate the spatial light, and generate modulated light, wherein the modulated light includes uniform light and / or structured light of at least one wavelength, wherein the uniform light may be monochromatic light or mixed light, and the structured light may be a preset digital barcode image. After being emitted from the light modulator 115, the modulated light travels along the second preset optical path, is incident on the projection optical system 11b, and is guided by the projection optical system 11b to be projected onto the platform carrying the object to be measured. In one embodiment, the modulated light emitted from the light modulator 115 is first incident on the second side m3 of the prism 114 along the second preset optical path, and the modulated light is reflected by the interface m2 of the prism 114, and then continues to travel along the preset second preset optical path, and enters the projection optical system 11b. In this case, the second preset optical path forms a bent optical path after being reflected by the prism 114. The propagation path of light in the RTIR prism is as follows: Figure 3 As shown. In some embodiments, the positions of the light modulator 115 and the RTIR prism are set to cooperate with the reflector 113 so that the direction of the structured light reflected by the RTIR prism is opposite to the direction of the emitted light of the shaping lens group 112, so that the overall light path of the light projection device 11 is in a folded shape, making the structure of the light projection device 11 more compact, thereby realizing the miniaturization of the sensor. Of course, those skilled in the art will understand that in an embodiment where the prism 114 is not used, the modulated light emitted by the light modulator 115 is directly incident on the projection optical system 11b along the second preset light path. In this case, the second preset light path is linear. Compared with the linear second preset light path, the bent second preset light path can make the light projection device 11 have a smaller volume, thereby realizing miniaturization and portability.

[0080] The projection optical system 11b is configured to receive the modulated light, guide the modulated light to travel along a second preset optical path, and project the modulated light onto the object to be measured in a direction that forms a first preset angle α with the object plane carrying the object to be measured. In a specific embodiment, the projection optical system 11b may include one lens or multiple lenses.

[0081] When implementing the folded and reflected optical path, in order to ensure that all parts of the light spot projected by the projection optical system 11b onto the object plane OP carrying the measured object can achieve consistent clarity requirements, the object plane OP, the main plane of the optical system and the image plane should theoretically comply with Scheimpflug's theorem. Figure 4 As shown, that is, the angle α between the object plane OP and the principal optical axis of the projection optical system 11b, the angle β between the image plane and the principal optical axis of the projection optical system 11b, and the magnification M on the principal optical axis of the projection optical system 11b are required to satisfy the relationship (1).

[0082] tan[π / 2-α] / tan[π / 2-β]=M ............. (1)

[0083] Wherein, α is the angle between the object plane OP and the main optical axis of the projection optical system 11b (hereinafter referred to as angle α), β is the angle between the plane where the light modulator 115 is located and the main optical axis of the projection optical system 11b (hereinafter referred to as angle β), π / 2-β is called the Sham angle or the tilt angle of the light modulator, and M is the magnification on the main optical axis of the projection optical system 11b. In this application, M is the magnification from the side of the object to be measured to the side of the light modulator. For the light projection device 11 with an RTIR prism in this application, if Figure 5 As shown, the object plane OP is the projection object plane where the platform for carrying the measured object is located. The modulated light projected by the light modulator 115 is reflected by the RTIR prism. According to the reflection theorem of light, the projection image plane where the light modulator 115 is located is equivalent to the projection image plane where the mirror image light modulator 115' of the light modulator 115 is located, which is symmetrical about the interface m2, that is, Figure 5 The projection image plane where the mirror light modulator 115' shown by the thick dashed line is located is the image plane. Therefore, the angle between the platform carrying the object to be measured and the main optical axis of the light projection lens is α, the angle between the light modulator 115 and the main optical axis of the light projection lens is β, and the extension lines of the projection object plane where the platform carrying the object to be measured is located, the main plane of the projection optical system, and the projection image plane 115' where the light modulator 115 is located intersect on a line and satisfy the relationship (1). For the light projection device 11 without an RTIR prism and the modulated light is not reflected by the RTIR prism, the second preset optical path is a straight line, and the image plane is directly the projection image plane where the light modulator 115 is located, the angle between the platform carrying the object to be measured and the main optical axis of the light projection lens is α, the angle between the light modulator 115 and the main optical axis of the modulated light emitted by it is β, and the extension lines of the projection object plane where the platform carrying the object to be measured is located, the main plane of the projection optical system, and the projection image plane where the light modulator 115 is located intersect on a line and satisfy the relationship (1).

[0084] In order to miniaturize the light detection sensor 1 , it is theoretically necessary to increase the angle β between the plane where the light modulator 115 is located and the principal optical axis of the projection optical system 11b (ie, reduce the Sham angle), that is, reduce the inclination of the light modulator 115 .

[0085] In addition, according to the inherent characteristics of the optical modulator 115, the light beam incident on the working surface of the optical modulator 115 needs to have a certain incident angle. The incident angle and the above-mentioned angle β jointly determine the reflection characteristics of the optical modulator 115. The larger the Sham angle, the more light energy is lost when it passes through the optical modulator 115. In addition, the Sham angle also restricts the material selection of the RTIR prism. The larger the Sham angle, the higher the refractive index of the RTIR prism material. The higher the refractive index, the greater the light energy absorption of the system radiation. Therefore, the light detection sensor 1 is expected to have a smaller Sham angle to improve the light energy transmission efficiency while satisfying the Sham theorem.

[0086] However, considering the system accuracy and design requirements, the angle α between the object plane OP and the principal optical axis of the projection optical system 11b and the magnification M cannot be changed after being determined. Therefore, the magnification M, the angle α and the angle β no longer meet the constraints of formula (1), resulting in the light spot projected by the projection optical system 11b onto the object plane OP becoming unclear, the edge of the light spot becoming blurred, and the clarity and uniformity of the light spot not meeting the projection requirements.

[0087] According to the reversibility of the optical path, assuming that the light is emitted from the side where the object is located (the object side), and the image is formed on the side where the light modulator 115 is located (the image side), that is, the light travels in the opposite direction of the second preset optical path. Then, when the plane where the object side is located, the plane where the image side is located, and the main plane of the projection optical system 11b satisfy the Scham's theorem, the modulated light projected by the object side can generate a Gaussian image surface on the image side. Figure 6 As shown, (γ1, γ3) represent the Gaussian image plane, γ1 is the field point on the Gaussian image plane located in the positive direction of the main optical axis of the projection optical system 11b, and γ3 is the field point on the Gaussian image plane located in the negative direction of the main optical axis of the projection optical system 11b, wherein γ1 and γ3 are symmetric about the optical axis in the positive projection direction (when β is 90°). (γ2, γ4) represent the plane where the light modulator 115 is located (hereinafter referred to as the actual image plane), γ2 is the field point on the actual image plane located in the positive direction of the main optical axis of the projection optical system 11b, and γ4 is the field point on the actual image plane located in the negative direction of the main optical axis of the projection optical system 11b, wherein γ2 and γ4 are symmetric about the optical axis in the positive projection direction (when β1 is 90°). Since the inclination angle β of the Gaussian image plane (γ1, γ3) shown by the dotted line relative to the optical axis is small, the light modulator 115 or the projection optical system 11b will produce spatial interference with the main device. In order to avoid interference, the relative positions of the illumination optical system 11a and the projection optical system 11b are kept unchanged, that is, the angle β between the plane where the light modulator 115 is located and the main optical axis of the projection optical system 11b is still kept at a large inclination angle, that is, Figure 6The actual image plane (γ2, γ4) shown by the solid line in the middle, the image on the actual image plane far from the optical axis will be blurred. Further research found that the field curvature aberrations at positions symmetrical with respect to the optical axis have opposite signs and equal absolute values, that is, |γ1-γ2|=|γ3-γ4|. At the same time, along the traveling direction of the main optical axis of the projection optical system 11b, in the positive direction of the main optical axis of the projection optical system 11b, the optical path of the field point γ1 on the Gaussian image plane is shorter than the optical path of the field point γ2 on the actual image plane, and in the negative direction of the main optical axis of the projection optical system 11b, the optical path of the field point γ3 on the Gaussian image plane is longer than the optical path of the field point γ4 on the actual image plane. Therefore, the present invention envisions shortening the optical path of the field point γ1 on the Gaussian image plane in the positive direction of the main optical axis of the projection optical system 11b through the design of the misalignment compensation system, so as to transform the field point γ1 on the Gaussian image plane into the field point γ2 in the positive direction of the main optical axis of the actual image plane; and extending the optical path of the field point γ3 on the Gaussian image plane in the negative direction of the main optical axis of the projection optical system 11b, so as to transform the field point γ3 on the Gaussian image plane into the field point γ4 in the negative direction of the main optical axis of the actual image plane. Then, according to the reversibility of light, when the light modulator 115 projects modulated light onto the object plane OP, compared with the original Sham projection optical system, the Sham projection optical system after misalignment compensation can also obtain a clear and uniform light spot on the object plane OP, or improve the clarity and uniformity of the light spot projected onto the object plane OP.

[0088] Based on this understanding, the inventive concept of the present invention is: under the condition that a large tilt angle is maintained between the light modulator 115 and the optical axis of the modulated light or the main optical axis of the projection optical system 11b, the uniformity and clarity of the projected light spot are improved by changing the optical path of the positive and negative parts of the main optical axis. The meaning of maintaining a large tilt angle between the light modulator 115 and the main optical axis of the projection optical system 11b is as follows:

[0089] Assume that the plane where the light modulation element 115 is located has a second preset angle β1 with the main optical axis of the projection optical system 11b, and the second preset angle β1 is an acute angle and is greater than the angle β determined based on the following formula:

[0090] tan[π / 2-α] / tan[π / 2-β]=M ............. (1)

[0091] Wherein, angle α is a first preset angle, M is a magnification of a set point on the optical axis, and angle β is an angle between the light modulator and the main optical axis of the projection optical system (i.e., the main optical axis of the second preset optical path) determined when the image plane, the main plane of the projection optical system, and the object plane carrying the measured object conform to the Sham's theorem. The value of the first preset angle α satisfies: 60°≤α≤70°, and the value of the second preset angle β1 satisfies: 5°≤90°-β1≤10°.

[0092] According to the concept of optical path, when a beam of light passes through Figure 7 When the optical system is shown, the total optical path is:

[0093] L=n1*l1+n2*l2+n3*l3+n4*l4+n5*l5+n6*l6

[0094] Where n is the refractive index of the medium and l is the distance the light travels in the medium.

[0095] Under normal circumstances, since the lens is usually a central rotationally symmetrical structure, the light beams passing through the lens are symmetrical based on the optical axis position and have equal optical paths. Studies have found that when a misalignment ΔX is applied to the optical system, the optical path change trend of the off-axis field of view symmetrical to the optical axis is just the opposite. Figure 7 As shown, the optical axis O2 of the optical system deviates from the main optical axis O1 of the projection optical system 11b by an amount ΔX. Taking the main optical axis O1 as a reference, assuming that the dashed line of the main optical axis O1 offset by -1 in the negative direction is taken as the straight line O2, and the dashed line symmetrical to the straight line O2 with respect to the main optical axis O1 is taken as the straight line O3 of the main optical axis O1 offset by +1 in the positive direction, taking the negative lens l1 with a refractive index of n1 as an example, the optical path of the straight line O2 is shorter than before the offset, and the optical path of the straight line O3 is longer than before the offset. Similarly, for media with refractive indices of n2, n3 (air), n4, n5 (air), and n6, the optical path variation trend of the field of view outside the ±1 axis is as follows: Figure 8 As shown, it can be found that the optical path of the ±1 axis field of view has the opposite trend in each lens. Therefore, when only field curvature correction is considered, a misalignment ΔX can be applied to one or more lenses in the projection optical system 11b, and the parameters of each lens in the projection optical system 11b (such as lens thickness, curvature and medium refractive index) can be designed to make the optical path of the field point γ2 of the actual image plane on the positive direction of the main optical axis of the projection optical system 11b shorter than before the offset, while the optical path of the field point γ4 of the actual image plane on the negative direction of the main optical axis of the projection optical system 11b becomes longer than before the offset, that is, the projection optical system 11b has a larger optical path than the projection optical system 11b. The optical path of the field point γ2 of the actual image plane in the positive direction of the principal optical axis b is smaller than the optical path of the field point γ4 of the actual image plane in the negative direction of the principal optical axis of the projection optical system 11b, so that the focus of the light in the positive direction of the principal optical axis of the projection optical system 11b moves forward, and the image on the focal plane is located on the actual image plane where γ2 and γ4 are located, or is closer to the actual image plane where γ2 and γ4 are located, while the focus of the light in the negative direction of the principal optical axis of the projection optical system 11b moves backward, and the image on the focal plane is located on the actual image plane where γ2 and γ4 are located, or is closer to the actual image plane where γ2 and γ4 are located.

[0096] Therefore, in the embodiment of the present invention, the projection optical system 11b includes a plurality of lenses (for example, N lenses), and the optical axes of some lenses (for example, M lenses among the N lenses, where M is greater than or equal to 1 and less than N) among the plurality of lenses are offset by a preset misalignment amount relative to the main optical axis of the projection optical system 11b. Based on the preset misalignment amount, by configuring the parameters such as the thickness, curvature, and medium refractive index of each lens in the projection optical system 11b, the main optical axis of the projection optical system 11b can be made positive (for example, Figure 2 The left side of the main optical axis of the projection optical system 11b is obliquely downward as the positive direction) and the optical path of the light is relative to the negative direction of the main optical axis of the projection optical system 11b (such as Figure 2 The optical path of the light at the symmetrical position (the right side of the main optical axis of the projection optical system 11b is negative) is shorter, so that the projection optical system 11b projects a clear and uniform light spot to the object plane OP.

[0097] In a specific embodiment, Fig. 9 As shown, the projection optical system 11b includes a front lens group 21 and a rear lens group 22. The front lens group 21 is arranged on the second preset optical path to receive the incident modulated light, for example, to receive the modulated light emitted by the light modulation element 115 and reflected by the prism 114. The front lens group 21 amplifies and eliminates aberrations of the modulated light. The rear lens group 22 is arranged on the second preset optical path and is located downstream of the front lens group 21 and is independently arranged relative to the front lens group 21 to receive the modulated light emitted by the front lens group 21. The rear lens group 22 is used to converge and eliminate aberrations of the modulated light, and direct the modulated light to form a first preset angle α( Figure 2 The optical axis of the rear lens group 22 coincides with the main optical axis O1 of the projection optical system 11b, the optical axis of the front lens group 21 is parallel to the main optical axis O1, and the optical axis O2 of at least a part of the lenses in the front lens group 21 is offset relative to the main optical axis O1 by a preset offset amount ΔX. For example, the optical axis O2 of at least a part or all of the lenses in the front lens group 21 can be offset relative to the main optical axis O1 in a positive or negative direction by a preset offset amount ΔX along a direction perpendicular to the main optical axis O1 of the projection optical system 11b. The figure shows an example in which the optical axis O2 of all the lenses in the front lens group 21 is offset negatively by a preset offset amount ΔX relative to the main optical axis O1. According to the optical path difference of the field of view point between the actual image plane and the Gaussian image plane, combined with the different parameters such as the thickness, curvature and medium refractive index of each lens, the optical axis O2 of some lenses in the front lens group 21 can also be set to be offset positively or negatively by a preset offset amount ΔX relative to the main optical axis O1. That is, one or more lenses in the front lens group 21 are offset relative to the main optical axis O1. When multiple lenses are offset, the preset offset amount ΔX of each lens can be the same or different. The present application does not impose any special restrictions on the specific manner in which each lens in the front lens group 21 is offset.

[0098] The front lens group 21 includes a second positive lens 211 and a second negative lens 212 arranged in sequence along the direction of the modulated light. When the modulated light is incident on the front lens group 21 along the second preset optical path, the modulated light can be converged by the second positive lens 211 and then magnified by the second negative lens 212, thereby eliminating the aberration between the second positive lens 211 and the second negative lens 212. In some embodiments, the second positive lens 211 and the second negative lens 212 are bonded to form a second bonded lens. The bonded lens can be centered at one time and assemble multiple lenses at the same time, thereby reducing the number of centering and assembly times of the lenses. In addition, the front lens group 21 may also include a third positive lens 213 and a fourth positive lens 214, the third positive lens 213 is close to the second positive lens 211 and is arranged upstream of the second positive lens 211 along the second preset optical path, and the fourth positive lens 214 is close to the third positive lens 213 and is arranged upstream of the third positive lens 213 along the second preset optical path. The third positive lens 213 and the fourth positive lens 214 are used to receive the incident modulated light and converge the incident divergent light. In addition, a plurality of positive and negative lenses and cemented lenses may be provided in the front lens group 21. The present application does not impose any special restrictions on the specific structure and number of each lens in the front lens group 21. In addition, the projection optical system 11b further includes an aperture 24, which is provided between the rear lens group 22 and the front lens group 21. The optical axis of the aperture 24 overlaps with the optical axis of the rear lens group 22, and is used to shield stray light and limit the size and / or shape of the light beam entering the rear lens group 22, thereby reducing the aberration outside the main optical axis of the projection optical system 11b. The focal length f of the rear lens group 22 is b The focal length f of the front lens group 21 d The ratio is: 0.5≤f d / f b ≤1.2, used to control the size range of the deformation of the light spot projected by the projection optical system 11b.

[0099] In some embodiments, the optical axis of the front lens group 21 can also be designed as the main optical axis O1. In this case, the optical axis of the front lens group 21 coincides with the main optical axis O1 of the projection optical system 11b, the optical axis of the rear lens group 22 is parallel to the main optical axis O1, and the optical axis of at least a portion of the lenses in the rear lens group 22 is offset relative to the main optical axis O1 by a preset offset amount ΔX. Similarly, according to the optical path difference of the field of view point between the actual image plane and the Gaussian image plane, combined with the difference in parameters such as the thickness, curvature and medium refractive index of each lens, the optical axis O2 of all lenses in the rear lens group 22 can be offset relative to the main optical axis O1 in a positive or negative direction by a preset offset amount ΔX, and the optical axis O2 of some lenses can also be set to be offset relative to the main optical axis O1 in a positive or negative direction by a preset offset amount ΔX. That is, one or more lenses in the rear lens group 22 are offset relative to the main optical axis O1. When multiple lenses are offset, the offset preset offset amount ΔX of each lens can be the same or different. The present application does not impose any special restrictions on the specific manner in which each lens in the rear lens group 22 is offset.

[0100] The rear lens group 22 includes a first negative lens 221 and a first positive lens 222 which are sequentially arranged along the direction of the modulated light. When the modulated light continues to be incident on the rear lens group 22 after passing through the front lens group 21 along the second preset optical path, the modulated light can be magnified by the first negative lens 221 and then converged by the first positive lens 222, thereby eliminating the aberration between the first negative lens 221 and the first positive lens 222, and the modulated light is projected to the object plane OP in a converged state. In some embodiments, the first negative lens 221 and the first positive lens 222 are bonded to form a first bonded lens. The first bonded lens can not only reduce the number of lens centering and assembly times, but also the first bonded lens can cooperate with the second bonded lens to eliminate the coma and field curvature of the modulated light, so that the projection optical system 11b projects a clear and uniform light spot to the object plane OP. Similarly, the rear lens group 22 can also be provided with a plurality of positive and negative lenses and bonded lenses. The present application does not impose any special restrictions on the specific structure and number of each lens in the rear lens group 22.

[0101] The projection optical system 11b is not limited to the front lens group 21 and the rear lens group 22. In order to better adjust the focal length, the projection optical system 11b may also include one or more intermediate lens groups. When the main optical axis O1 passes through at least one of the front lens group 21 and the rear lens group 22, some or all of the lenses in the intermediate lens group are offset by a preset offset amount ΔX relative to the main optical axis O1, so that the projection optical system 11b can also use the intermediate lens group to adjust the optical path of the modulated light, so that the actual image plane of the light modulation element 115 is closer to the Gaussian image plane. In some embodiments, the projection optical system 11b may also be provided with a group of lens groups including a plurality of lenses. The plurality of lenses may be independent lenses or may be lenses glued to each other. A portion of the plurality of lenses is offset by a preset offset amount ΔX relative to the main optical axis O1 of the projection optical system 11b, so that the projection optical system 11b projects a clear and uniform light spot. The present application does not impose any special restrictions on the number of lens groups in the projection optical system 11b.

[0102] In order to ensure the relative fixation between the main optical axis O1 of the projection optical system 11b and the optical axis O2 after the preset offset amount ΔX, the projection optical system 11b further includes a first packaging structure 23, and the first packaging structure 23 encapsulates the front lens group 21 and the rear lens group 22 therein, so that the relative position of the front lens group 21 and the rear lens group 22 can be fixed and maintained. For example, the first packaging structure 23 is set as a cylindrical structure with two barrel cavities, and the front lens group 21 and the rear lens group 22 are respectively installed in the two barrel cavities. Since the preset offset amount of the optical axis of the front lens group 21 and the rear lens group 22 is ΔX, the central axes of the two barrel cavities also need to be mutually offset by ΔX to ensure that the relative position of the front lens group 21 and the rear lens group 22 can be fixed and maintained. In other embodiments, the first packaging structure 23 can also be set as two independent cylindrical structures, and the front lens group 21 and the rear lens group 22 are respectively installed in the two cylindrical structures, and then the two cylindrical structures are assembled with the offset amount ΔX. Of course, the shape of the first packaging structure 23 is not limited to the cylindrical shape. Depending on the different assembly environments of the projection optical system 11b in the light projection device 11, the first packaging structure 23 can also be set to other shapes such as a box or a bracket. Among them, the preset misalignment amount ΔX is: 0.05mm≤ΔX≤0.5mm. When ΔX<0.05mm, due to the small misalignment of the lens, the effect of shortening or increasing the optical path of the main optical axis of the projection optical system 11b is not obvious, resulting in an insignificant improvement in the light spot projected by the projection optical system 11b. When ΔX>0.5mm, the first packaging structure 23 requires a larger accommodation space, which is not conducive to the miniaturization of the light detection sensor 1.

[0103] Normally, the optical axes of the multiple lenses in the projection optical system 11b coincide with the principal optical axis, and the field principal ray on the optical axis does not deviate from the principal optical axis when passing through the center of curvature of each lens. The present application reasonably matches the misalignment compensation of the lenses in the projection optical system 11b, presets a certain misalignment amount for a part of the multiple lenses, so that the center of curvature of this part of the lenses deviates from the main optical axis of the projection optical system 11b. When the light beam propagates in the misalignment compensated lens, the field of view points originally symmetrical about the optical axis will produce an optical path difference that is either shortened or increased. The optical path difference generated by the optical axis offset can compensate for the optical path difference of the field of view points of the actual image plane of the light modulator 115 relative to the Gaussian image plane in the positive and negative directions of the main optical axis, so that the inclination angle between the light modulator 115 and the main optical axis under the premise of satisfying the Sham's theorem can be transformed from the Gaussian image plane with a larger Sham's angle to the actual image plane with a smaller Sham's angle, thereby achieving that when the projection optical system 11b works in a low-magnification state, the light modulator 115 has a smaller Sham's angle without causing spatial interference problems between the light modulator 115 and other optical elements in the light detection sensor 1, thereby realizing the miniaturization of the light detection sensor 1, reducing the light energy transmission loss, and improving the light energy transmission efficiency of the light detection sensor 1. At the same time, when the light modulator 115 adopts a smaller Sham angle, the modulated light projected onto the object plane OP by the projection optical system 11b can still meet the characteristic requirements of high definition and high uniformity through the misalignment compensation system.

[0104] Under the condition that the Scham's theorem is satisfied, the Gaussian image surface changes before and after the lens in the projection optical system 11b is offset relative to the main optical axis O1 as shown in Fig.10As shown, according to the requirements of Sham's theorem, when the extended lines of the object plane OP (the plane where the platform carrying the object to be measured is located), the principal plane of the projection optical system 11b (the plane where the lens is located), and the image plane (the plane where the light modulator 115 is located) intersect in a line, the projection optical system 11b can project a clear and uniform light spot. Before the lens in the projection optical system 11b is offset relative to the principal optical axis O1, as shown by the dotted line in the figure, the object plane OP, the principal plane 1 and the image plane 1 intersect at the P1 line. After the lens in the projection optical system 11b is offset relative to the principal optical axis O1, as shown by the solid line in the figure, the object plane OP, the principal plane 2 and the image plane 2 intersect at the P2 line. Therefore, offsetting the lens in the projection optical system 11b relative to the principal optical axis O1 is equivalent to moving the principal plane 1 in the opposite direction of the principal optical axis O1 to the principal plane 2, so that the intersection line of the object plane OP, the principal plane, and the image plane changes from the P1 line to the P2 line. In this change, the inclination angle of the image plane relative to the principal optical axis O1 increases from β to β1, that is, the inclination angle of the Gaussian image plane of the projection optical system 11b relative to the principal optical axis O1 increases from β to β1, so that the light modulator 115 only needs to adjust a smaller inclination angle relative to the principal optical axis O1 or even keep it unchanged, so that the actual image plane of the light modulator 115 can be close to the Gaussian image plane or coincide with the Gaussian image plane.

[0105] For a better understanding of the present application, the following embodiments will be presented with actual data. In this embodiment, the technical indicators of the optical system are as follows:

[0106] Circular field of view (orthographic projection): 35mm;

[0107] Band: blue light;

[0108] Magnification: 3.5X;

[0109] Working distance: 125mm;

[0110] Throw ratio (orthographic projection): 3.69;

[0111] F#: 8.0;

[0112] Distortion: 0.16%;

[0113] Total optical length: 65mm;

[0114] Optical weight: 14.7g;

[0115] The specific parameters of each lens in the projection optical system 11b are as follows: Fig.11 As shown, combined Fig. 9 As shown, from left to right, according to the equivalent lenses of the first positive lens 222, the first negative lens 221, the second negative lens 212, the second positive lens 211, the third positive lens 213, the fourth positive lens 214, and the prism 114 ( Figure 2 The order of the prism 114 is as follows: the first surface to the tenth surface, wherein the light-emitting surface of the first positive lens 222 is the first surface, the bonding surface between the first negative lens 221 and the first positive lens 222 is the second surface, the light-entering surface of the first negative lens 221 is the third surface, the light-emitting surface of the second negative lens 212 is the fourth surface, the bonding surface between the second negative lens 212 and the second positive lens 211 is the fifth surface, and the other surfaces are analogous to each other, and the eleventh surface and the twelfth surface are two equivalent surfaces of the equivalent lens of the prism 114. The air gap between the second positive lens 211 and the third positive lens 213 is 0.1 mm, the air gap between the third positive lens 213 and the fourth positive lens 214 is 0.2 mm, and the air gap between the fourth positive lens 214 and the prism 114 is 11.9 mm. The thickness of the first positive lens 222 is 2.18 mm, the thickness of the first negative lens 221 is 4.9 mm, the thickness of the second negative lens 212 is 5.89 mm, the thickness of the second positive lens 211 is 3.7 mm, the thickness of the third positive lens 213 is 3.24 mm, the thickness of the fourth positive lens 214 is 3.68 mm, and the thickness of the prism 114 is 16.5 mm.

[0116] Figure 12-14 The effect of the misalignment compensation of the present invention is described, wherein curves of different colors represent transfer function curves of different sampling points in the projection spot.

[0117] According to the Sham's theorem, if the misalignment compensation of the present invention is not adopted, and the tilt angle β of the light modulator 115 is not changed (the plane where the light modulator 115 is located satisfies the Sham's theorem), for example, the light modulator 115 has a smaller tilt angle β=81.4° relative to the main optical axis O1, that is, the light modulator 115 has a larger Sham's angle of 90°-81.4°=8.6°. When the projection optical system 11b projects a light spot onto the object plane OP, as shown in FIG. Fig.12 As shown, it can be seen that the modulation transfer function value of each sampling point of the projection optical system 11b is greater than 0.3 when the spatial frequency is 90lp / mm, indicating that the field of view of each sampling point is relatively uniform, and the modulation transfer function of different sampling points has good consistency, and the light spot is clear and uniform.

[0118] If the misalignment compensation of the present invention is not adopted, but the tilt angle of the light modulator 115 is directly increased from β to β1, for example, the increased tilt angle of the light modulator 115 relative to the main optical axis O1 is set to 85°, that is, the Sham angle of the light modulator 115 is 90°-85°=5°. Fig.13 As shown, it can be seen that the modulation transfer function values ​​of each sampling point of the projection optical system 11b are mostly less than 0.2 when the spatial frequency is 90lp / mm, indicating that the field of view of each sampling point is uneven, and the modulation transfer functions of different sampling points are more dispersed, the consistency is poor, and the clarity and uniformity of the light spot are poor.

[0119] If the offset compensation of the present invention is adopted (for example, the offset amount ΔX of the front lens group 21 offset from the main optical axis O1 is set to 0.163 mm), and the tilt angle of the light modulator 115 relative to the main optical axis O1 is kept at 85°. Fig.14 As shown, it can be seen that the modulation transfer function value of each sampling point of the projection optical system 11b is greater than 0.2 when the spatial frequency is 90lp / mm, indicating that the field of view of each sampling point tends to be uniform, and the modulation transfer functions of different sampling points tend to be consistent, and the clarity and uniformity of the light spot are significantly improved.

[0120] In addition, if Fig.15 As shown, by presetting the offset amount ΔX of the optical axis of the front lens group 21 relative to the main optical axis O1 in the negative direction, the relative illumination of each sampling point is made to approach 1, that is, the brightness uniformity of the light spot projected by the projection optical system 11b is better.

[0121] It can be seen that, when the light modulator 115 maintains a small Sham angle relative to the main optical axis O1, by applying a certain amount of misalignment compensation to the lens in the projection optical system 11b, the field curvature of the projection optical system 11b can be compensated, thereby improving the clarity and uniformity of the light spot projected by the projection optical system 11b. Therefore, for the projection optical system 11b with limited spatial size, the method of offsetting the optical axis of the lens and the method of adjusting the tilt angle of the light modulator 115 relative to the main optical axis, or a combination of the two, can be selected to improve the clarity and uniformity of the light spot projected by the projection optical system 11b, thereby facilitating the miniaturization of the light detection sensor 1.

[0122] In some embodiments, the scheme of offsetting each lens in the projection optical system 11b by a preset misalignment amount ΔX to compensate for the imaging field curvature is not only applicable to the field of light detection sensors 1, but also applicable to other optical devices such as cameras and projectors. The optical module in these optical devices includes a front lens group, a rear lens group and a first packaging structure, wherein the front lens group is used to receive incident light, and amplify and eliminate aberrations of the incident light; the rear lens group is arranged downstream of the front lens group along the optical path and is independently arranged relative to the front lens group, and is used to converge and eliminate aberrations of the light emitted by the front lens group, and project the light onto the object to be measured in a direction that is at a first preset angle to the object plane carrying the object to be measured; the optical axis of the rear lens group coincides with the main optical axis of the optical module, the optical axis of the front lens group is parallel to the main optical axis, and the optical axis of at least a part of the lenses in the front lens group is offset by a preset misalignment amount relative to the main optical axis; the first packaging structure encapsulates the front lens group and the rear lens group therein, so that the relative positions of the front lens group and the rear lens group are fixed and maintained. The optical axes of at least a part or all of the lenses in the front lens group are offset by a preset misalignment amount in a direction perpendicular to the main optical axis of the projection optical system in a positive or negative direction relative to the main optical axis. The thickness, curvature and medium refractive index of each lens in the front lens group are configured so that the optical path of light in the positive direction of the main optical axis of the optical module after passing through the front lens group is shorter than the optical path of light in a symmetrical position in the negative direction of the main optical axis of the optical module after passing through the front lens group.

[0123] In other embodiments, the optical module of these optical devices includes a front lens group, a rear lens group and a first packaging structure, wherein the front lens group is used to receive incident light, and amplify and eliminate aberration of the incident light; the rear lens group is arranged downstream of the front lens group along the optical path and is independently arranged relative to the front lens group, and is used to converge and eliminate aberration of the light emitted by the front lens group, and project the light onto the object to be measured in a direction that forms a first preset angle with the object plane carrying the object to be measured; the optical axis of the front lens group coincides with the main optical axis of the optical module, the optical axis of the rear lens group is parallel to the main optical axis, and the optical axis of at least a part of the lenses in the rear lens group is offset by a preset misalignment amount relative to the main optical axis; the first packaging structure encapsulates the front lens group and the rear lens group therein, so that the relative positions of the front lens group and the rear lens group are fixed and maintained. Wherein, the optical axes of at least a part or all of the lenses in the rear lens group are offset by a preset misalignment amount relative to the main optical axis in a direction perpendicular to the main optical axis of the projection optical system in a positive or negative direction. The thickness, curvature and medium refractive index of each lens in the rear mirror group are configured so that the optical path of light in the positive direction of the main optical axis of the optical module after passing through the rear mirror group is shorter than the optical path of light in a symmetrical position in the negative direction of the main optical axis of the optical module after passing through the rear mirror group.

[0124] The method provided in this embodiment, the specific process of each step can be executed by the corresponding module in the system / device, that is, the specific process of each step can be found in the functional description of each module in the aforementioned system / device embodiment, and will not be repeated here.

[0125] This document is described with reference to various exemplary embodiments. However, those skilled in the art will recognize that changes and modifications may be made to the exemplary embodiments without departing from the scope of this document. For example, various operating steps and components for performing the operating steps may be implemented in different ways (e.g., one or more steps may be deleted, modified, or incorporated into other steps) depending on the specific application or considering any number of cost functions associated with the operation of the system.

[0126] Although the principles of this invention have been shown in various embodiments, many modifications of structures, arrangements, proportions, elements, materials and components particularly suitable for specific environments and operational requirements can be used without departing from the principles and scope of this invention. The above modifications and other changes or amendments will be included in the scope of this invention.

[0127] The foregoing specific description has been described with reference to various embodiments. However, those skilled in the art will recognize that various modifications and changes can be made without departing from the scope of the present disclosure. Therefore, the consideration of the present disclosure will be illustrative rather than restrictive, and all these modifications will be included in its scope. Similarly, the advantages, other advantages and solutions to the problems of various embodiments have been described above. However, the benefits, advantages, solutions to the problems and any elements that can produce these, or make them more clear, should not be interpreted as critical, necessary or necessary. The term "include" and any other variants used in this article are all non-exclusive inclusions, so that the process, method, article or device including the list of elements not only includes these elements, but also includes other elements that are not explicitly listed or do not belong to the process, method, system, article or device. In addition, the term "coupled" and any other variants used in this article refer to physical connections, electrical connections, magnetic connections, optical connections, communication connections, functional connections and / or any other connections.

[0128] Those skilled in the art will appreciate that many changes may be made to the details of the above-described embodiments without departing from the basic principles of the invention. Therefore, the scope of the present invention should be determined solely by the claims.

Claims

1. A light projection device, characterized in that: include: an illumination optical system configured to emit light having at least one wavelength and cause the emitted light to travel along a first preset optical path; a light modulation element configured to receive light emitted by the illumination optical system, modulate the light, and generate modulated light, wherein the modulated light travels along a second preset optical path after being emitted from the light modulation element, and the modulated light includes uniform light and / or structured light of at least one wavelength; A projection optical system is configured to receive the modulated light, guide the modulated light along a second preset optical path, and project the modulated light onto the object to be measured in a direction that forms a first preset angle α with an object plane carrying the object to be measured; the projection optical system includes a plurality of lenses, and the optical axes of some of the lenses in the plurality of lenses are offset by a preset misalignment amount relative to the main optical axis of the projection optical system.

2. The light projection device according to claim 1, wherein: The projection optical system comprises: A front lens group is arranged on a second preset optical path, receives the incident modulated light, and amplifies and eliminates aberrations of the modulated light; A rear lens group, which is arranged on a second preset optical path and is located downstream of the front lens group and is independently arranged relative to the front lens group, and is used to converge and eliminate aberrations of the modulated light, and project the modulated light onto the object to be measured in a direction that forms a first preset angle α with the object plane carrying the object to be measured; The optical axis of the rear mirror group coincides with the main optical axis of the projection optical system, the optical axis of the front mirror group is parallel to the main optical axis, and the optical axes of at least a part of the lenses in the front mirror group are offset by a preset misalignment amount relative to the main optical axis; or the optical axis of the front mirror group coincides with the main optical axis of the projection optical system, the optical axis of the rear mirror group is parallel to the main optical axis, and the optical axes of at least a part of the lenses in the rear mirror group are offset by a preset misalignment amount relative to the main optical axis.

3. The light projection device according to claim 2, characterized in that The optical axes of at least a part or all of the lenses in the front lens group are offset in a positive or negative direction relative to the main optical axis of the projection optical system by a preset misalignment amount along a direction perpendicular to the main optical axis of the projection optical system; or The optical axes of at least a part or all of the lenses in the rear mirror group are offset by a preset misalignment amount relative to the main optical axis in a direction perpendicular to the main optical axis of the projection optical system in a positive or negative direction.

4. The light projection device according to claim 1, wherein: The preset misalignment amount ΔX is: 0.05mm≤ΔX≤0.5mm.

5. The light projection device according to any one of claims 1 to 4, characterized in that: The plane where the light modulation element is located and the main optical axis of the second preset optical path have a second preset angle β1, and the second preset angle β1 is an acute angle and is greater than the angle β determined based on the following formula: tan[π / 2-α] / tan[π / 2-β]=M Among them, angle α is a first preset angle, M is the magnification of the set point on the optical axis, and angle β is the angle between the main optical axis of the light modulation element and the second preset optical path determined when the image plane, the main plane of the projection optical system and the object plane carrying the object to be measured conform to Scham's law.

6. The light projection device according to claim 5, characterized in that The value of the first preset angle α satisfies: 60°≤α≤70°, The value of the second preset angle β1 satisfies: 5°≤90°-β1≤10°.

7. The light projection device according to claim 5, characterized in that The rear lens group includes a first negative lens and a first positive lens which are sequentially arranged along the traveling direction of the modulated light, and the front lens group includes a second positive lens and a second negative lens which are sequentially arranged along the traveling direction of the modulated light.

8. The light projection device according to claim 7, characterized in that The first positive lens and the first negative lens are bonded to form a first bonded lens, and the second negative lens and the second positive lens are bonded to form a second bonded lens.

9. The light projection device according to claim 8, characterized in that The front lens group also includes a third positive lens and a fourth positive lens. The third positive lens is close to the second positive lens and is arranged upstream of the second positive lens along the second preset optical path. The fourth positive lens is close to the third positive lens and is arranged upstream of the third positive lens along the second preset optical path.

10. The light projection device according to claim 2, characterized in that: It also includes an aperture, which is arranged between the rear lens group and the front lens group, and the optical axis of the aperture overlaps with the optical axis of the rear lens group.

11. The light projection device according to claim 2, characterized in that The focal length f of the rear mirror group b The focal length f of the front lens group d The ratio is: 0.5≤f d / f b ≤1.

2.

12. The light projection device according to claim 5, characterized in that Based on the preset misalignment amount, the thickness, curvature and medium refractive index of each lens in the projection optical system are configured so that the optical path of light in the positive direction of the main optical axis of the projection optical system is shorter than the optical path of light in a symmetrical position in the negative direction of the main optical axis of the projection optical system.

13. The light projection device according to claim 1, wherein: The light modulation element is a digital micromirror device or a reflective liquid crystal element.

14. The light projection device according to claim 1, wherein: The projection optical system further comprises a first packaging structure, wherein the first packaging structure packages the front lens group and the rear lens group therein, so that the relative positions of the front lens group and the rear lens group are fixed and maintained.

15. An optical module, characterized in that: include: The front lens group is used to receive incident light, amplify the incident light and eliminate aberration; a rear mirror group, which is arranged downstream of the front mirror group along the optical path and is independently arranged relative to the front mirror group, and is used to converge and eliminate aberrations of light emitted by the front mirror group, and project the light onto the object to be measured in a direction that forms a first preset angle with the object plane carrying the object to be measured; the optical axis of the rear mirror group coincides with the main optical axis of the optical module, the optical axis of the front mirror group is parallel to the main optical axis, and the optical axis of at least a part of the lenses in the front mirror group is offset by a preset misalignment amount relative to the main optical axis; A first packaging structure, wherein the first packaging structure packages the front lens group and the rear lens group therein, so that the relative positions of the front lens group and the rear lens group are fixed and maintained.

16. The optical module according to claim 15, wherein: The optical axes of at least a portion or all of the lenses in the front lens group are offset by a preset misalignment amount relative to the main optical axis in a direction perpendicular to the main optical axis of the projection optical system in a positive or negative direction.

17. The optical module according to claim 16, wherein: The thickness, curvature and medium refractive index of each lens in the front lens group are configured so that the optical path of light in the positive direction of the main optical axis of the optical module after passing through the front lens group is shorter than the optical path of light in a symmetrical position in the negative direction of the main optical axis of the optical module after passing through the front lens group.

18. An optical module, characterized in that: include: The front lens group is used to receive incident light, amplify the incident light and eliminate aberration; a rear mirror group, which is arranged downstream of the front mirror group along the optical path and is independently arranged relative to the front mirror group, and is used to converge and eliminate aberrations of light emitted by the front mirror group, and project the light onto the object to be measured in a direction that forms a first preset angle with the object plane carrying the object to be measured; the optical axis of the front mirror group coincides with the main optical axis of the optical module, the optical axis of the rear mirror group is parallel to the main optical axis, and the optical axis of at least a part of the lenses in the rear mirror group is offset by a preset misalignment amount relative to the main optical axis; A first packaging structure, wherein the first packaging structure packages the front lens group and the rear lens group therein, so that the relative positions of the front lens group and the rear lens group are fixed and maintained.

19. The optical module according to claim 18, wherein: The optical axes of at least a part or all of the lenses in the rear mirror group are offset by a preset misalignment amount relative to the main optical axis in a direction perpendicular to the main optical axis of the projection optical system in a positive or negative direction.

20. The optical module according to claim 19, wherein: The thickness, curvature and medium refractive index of each lens in the rear mirror group are configured so that the optical path of light in the positive direction of the main optical axis of the optical module after passing through the rear mirror group is shorter than the optical path of light in a symmetrical position in the negative direction of the main optical axis of the optical module after passing through the rear mirror group.

21. The optical module according to any one of claims 15 to 20, characterized in that: The preset misalignment amount ΔX is: 0.05mm≤ΔX≤0.5mm.

22. A light detection sensor, characterized in that: include: The light projection device according to any one of claims 1 to 14; An image acquisition device, the image acquisition device includes a light receiving system and an imaging system, the optical axis of the light receiving system is perpendicular to the object plane used to carry the object to be measured, receives diffusely reflected modulated light within at least a partial angle formed by diffuse reflection of the object to be measured after being irradiated by the modulated light, and guides the diffusely reflected modulated light to the imaging system, the imaging system generates height image data reflecting height information of the object to be measured and / or texture image data reflecting texture information of the object to be measured based on the diffusely reflected modulated light.

Images