Optical system device and housing used for said optical system device

Abstract

The objective of the present invention is to provide an optical system device that reduces the influence of delay and noise to improve measurement accuracy in a three-dimensional measurement sensor using a time-of-flight (TOF) method.　This optical system device comprises: a light irradiation means 1 capable of irradiating light 10; an optical element 3 exerting an optical function on the light 10; and a housing 2 including the light irradiation means 1 together with the optical element 3, and is characterized in that the housing 2 has a light extraction part 21 for extracting the light of the light irradiation means 1 to a predetermined position.

Description

Optical system device and housing used for the optical system device ,

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[0001] The present invention relates to an optical system device and a housing used for the optical system device.

[0002] Three-dimensional measurement sensors using the time-of-flight (TOF) method have begun to be adopted in various fields such as mobile devices, vehicles, robots, and drones. This sensor can calculate the distance to an object with high accuracy by measuring the time it takes for the light irradiated from the light source to the object to be reflected back. Also, if the distances at multiple positions on the object can be measured, the three-dimensional structure of the object can be accurately reproduced, so it can also be used for three-dimensional mapping and spatial scanning. In addition, since the TOF method can measure distances quickly and accurately, it is very useful for purposes such as object recognition, obstacle avoidance, and spatial perception.

[0003] The above sensor system is composed of a light emitting unit that irradiates light onto an object, a light receiving unit that detects the light reflected from the object, and an arithmetic unit that calculates the distance to the object from the signal received by the light receiving unit. By irradiating light in a predetermined range by the light emitting unit, the distance at each point within the irradiation area can be measured, so detailed three-dimensional information of the object can be obtained.

[0004] Conventionally, in such a system, the timing of the light irradiation by the light emitting unit is controlled by an electrical signal. Based on this, the distance can be calculated from the difference between the time when the light is irradiated and the time when the light reflected from each point of the object is detected (for example, Patent Document 1).

[0005] JP-A-2024-13232

[0006] However, control by an electrical signal may cause minute delays or the influence of noise. When the influence of delay or noise occurs, an error occurs in the distance calculation, which becomes a factor affecting the measurement accuracy. Also, if the design is such that the start time of the light irradiation of the irradiation unit is detected outside the system, external light may interfere, making accurate distance measurement difficult. Therefore, in order to perform high-precision measurement without being affected by delay or noise, a new design or device for reliably detecting the irradiation start time is required.

[0007] Therefore, the present invention aims to provide an optical system that reduces the effects of delay and noise and improves measurement accuracy, as well as a housing used for said optical system.

[0008] To achieve the above objective, the optical system of the present invention comprises a light irradiation means capable of irradiating light, an optical element that exhibits an optical function with respect to the light, and a housing that encloses the light irradiation means together with the optical element, wherein the housing has a light extraction section for extracting the light from the light irradiation means to a predetermined position.

[0009] In this case, it is preferable that the light extraction unit be positioned outside the range of the light emission angle of the light irradiation means.

[0010] Another optical system of the present invention comprises a light irradiation means capable of irradiating light, an optical element that performs an optical function with respect to the light, and a housing that encloses the light irradiation means together with the optical element, wherein the optical element has a light extraction section for extracting light that has propagated inside the optical element from the light irradiation means to the outside.

[0011] Furthermore, the optical system of the present invention may include a light detection means for detecting the light extracted by the light extraction unit. In this case, a waveguide connecting the light extraction unit and the light detection means may also be included.

[0012] Furthermore, the light detection means may be provided with a bandpass filter to suppress light other than the wavelength band irradiated by the light irradiation means from entering the light detection means.

[0013] Furthermore, the optical system of the present invention may include a light detection means for detecting reflected light from the light emitted by the light irradiation means that has passed through the optical element.

[0014] Furthermore, the housing of the present invention is used in the optical system device of the present invention described above, and is characterized by having a light irradiation means set section for arranging the light irradiation means, an optical element set section for arranging optical elements, and a light extraction section for extracting light from the light irradiation means to the outside.

[0015] This invention provides an optical system that reduces the effects of delay and noise and improves measurement accuracy, as well as a housing for the said optical system.

[0016] This is a schematic cross-sectional view showing the optical system of the present invention. This is a schematic configuration diagram showing another optical system of the present invention. This is a schematic plan view showing yet another optical system of the present invention. This is yet another schematic configuration diagram showing an optical system of the present invention.

[0017] The optical system of the present invention will now be described. As shown in Figure 1, the optical system of the present invention consists of a light irradiation means 1 capable of irradiating light 10, an optical element 3 that performs an optical function with respect to the light 10, and a housing 2 that encloses the light irradiation means 1 together with the optical element 3. The optical system of the present invention may further include a light detection means 5 for detecting the light 10.

[0018] The light irradiation means 1 is for irradiating light 10, and for example, it can be a light source that irradiates the optical element 3 with the light 10 necessary for the purpose. In this case, the light irradiation means 1 may be a single light source or multiple light sources. Alternatively, it may be a multiple light source created by passing the light from a single light source through an aperture in which multiple pores are formed. When the light irradiation means 1 is composed of multiple light sources, it is preferable that the light sources be formed on the same plane, as this allows for precise adjustment of the distance and angle with respect to the optical element 3. Specific examples of the light irradiation means 1 include LEDs and VCSELs (Vertical Cavity Surface Emitting Lasers) which can be expected to produce high output with low power consumption. VCSELs include single-emitter VCSELs which have one light source that can irradiate light in a direction perpendicular to the light-emitting surface, and multi-emitter VCSELs which have multiple light sources. The light irradiation means 1 may also consist of multiple LEDs or VCSELs.

[0019] The wavelength of the light 10 emitted by the light irradiation means 1 should be appropriately selected depending on the application and purpose. For example, when used as a 3D measurement sensor, it is preferable to use infrared light or light with a longer wavelength, taking into consideration the strain on the eyes and safety for the human body. Infrared light has a longer wavelength than visible light and has less impact on the human body, as well as being suitable for capturing the surface characteristics of objects, thus enabling highly accurate measurements in distance measurement and shape recognition. In addition, because infrared light is less affected by visible light, stable measurements are possible even outdoors or in environments where a lot of light enters.

[0020] The optical element 3 performs an optical function with respect to the light 10 emitted by the light irradiation means 1. The optical element 3 has, for example, a concave and convex shape that provides an optical function with respect to the light 10 emitted by the light irradiation means 1. The concave and convex shape can be any shape that can perform an optical function, such as light distribution control. For example, a microlens array (MLA), a diffractive optical element (DOE), a metalens, etc., is suitable as a shape that can control and emit the light 10 incident from the light irradiation means 1. The lenses of the microlens array may be arranged periodically or randomly. Furthermore, the concave and convex shape can be controlled in any way according to the application, as long as it controls the light 10 of the light irradiation means 1 and performs an optical function. For example, the concave and convex shape may be such that it irradiates the entire irradiation area with a predetermined light distribution, irradiates in a dot pattern, or irradiates in a line pattern. Furthermore, the optical element 3 has a first surface on which the light 10 from the light irradiation means 1 is incident and a second surface on which the controlled light 10 is emitted. The uneven shape may be formed on either the first surface or the second surface of the optical element 3, or on both surfaces.

[0021] The optical element 3 can be made of any material that can control the light 10 of the light irradiation means 1 to exhibit optical functions. For example, a flexible and easily moldable resin such as polydimethylsiloxane (PDMS) or glass with high transparency and durability can be used. Furthermore, the optical element 3 can be manufactured in any way, using well-known techniques such as imprint printing or injection molding.

[0022] The housing 2 includes a light irradiation means set section 25 for arranging the light irradiation means 1, an optical element set section 26 for arranging the optical element 3, and a light extraction section 21 for extracting the light 10 from the light irradiation means 1 to a predetermined position. This allows the light irradiation means 1 and the optical element 3 to be arranged and to function and be protected appropriately.

[0023] The light irradiation means set section 21 is for positioning the light irradiation means 1 in a predetermined location within the housing 2. By fixing the light irradiation means 1 to the light irradiation means set section 21, the X, Y, and Z directions, as well as the rotation angle and optical axis direction, are positioned relative to the housing 2 and the optical element 3 placed in the housing 2. This allows the light 10 from the light irradiation means 1 to be properly irradiated onto the optical element 3. In Figure 1, a bottomed cylindrical housing 2 with an integrated bottom and sides is used, but the bottom and cylindrical sides may be joined together with adhesive or the like. In this case, the substrate of the light irradiation means 1 can be used as the bottom.

[0024] The optical element set section 26 is for positioning the optical element 3 at a predetermined location within the housing 2. By fixing the optical element 3 to the optical element set section 26, the X, Y, and Z directions, as well as the rotation angle and optical axis direction, are positioned relative to the housing 2 and the light irradiation means 1 located within the housing 2. Furthermore, by positioning the optical element 3 in the optical element set section 26, the housing 2 can form an internal space capable of enclosing the light irradiation means.

[0025] The light extraction unit 21 is for extracting the light 10 from the light irradiation means 1 to a predetermined location such as the outside of the housing 2 or the light detection means 5. By detecting the light 10 extracted from the light extraction unit 21 with the light detection means 5, the timing of the light irradiation means 1 irradiating the light 10 can be accurately detected. The light 10 irradiated by the light irradiation means 1 passes through the optical element 3 arranged in the housing 2 and is irradiated to the outside of the housing 2, but some of the light 10 is reflected by the optical element 3. Therefore, as shown in Figure 1, the light extraction unit 21 can also be placed outside the range of the emission angle of the light 10 from the light irradiation means 1. If the light extraction unit 21 is placed at the position where the reflected light is incident, the reflected light can be extracted and effectively utilized.

[0026] The light extraction unit 21 is not particularly limited in shape or material, as long as it can transmit light 10 from the light irradiation means 1 to the outside. For example, the light extraction unit 21 can be formed as a communication opening in the bottom or side of the housing 2, connecting the internal space to the outside. The communication opening may contain gas or be in a vacuum state, but it may also be filled with a transparent material such as glass or resin that allows light 10 to pass through easily. This allows the light extraction unit 21 to have a structure that also protects it from the external environment. Any resin that is transparent to light 10 can be used to fill the communication opening, but examples include acrylic resin, epoxy resin, and silicone resin.

[0027] The housing 2 can have any shape or material as long as it has a light irradiation means set section 21, an optical element set section 26, and a light extraction section 21. Preferably, in order to prevent the light 10 irradiated by the light irradiation means 1 from leaking unintentionally, the material of the housing 2 is preferably one that does not transmit the light 10 from the light irradiation means 1. Also, in order to prevent being affected by unwanted light from the outside, the material of the housing 2 is preferably one that does not transmit at least external light. For this reason, the housing 2 is selected from a material and shape that has excellent light-shielding properties. For example, it is preferable for the housing 2 to be thicker or to be treated to prevent reflection. Furthermore, the housing 2 can be manufactured in any way, and well-known techniques such as injection molding can be used.

[0028] Furthermore, while the optical element 3 transmits or reflects the light 10 from the light irradiation means 1, it is known that some of the light 10 propagates inside the optical element 3, as shown in Figure 2. Therefore, although the above description described the case in which a light extraction section 21 is formed on the housing 2, it is also possible to form a light extraction section 31 on the optical element 3, as shown in Figure 2. The light extraction section 31 can be anything as long as it is for extracting the light 10 that has propagated inside the optical element 3 from the light irradiation means 1 to the outside. For example, a pattern of irregularities can be formed on the first surface, second surface, or side surface of the optical element 3 to facilitate the extraction of light 10 from the inside to the outside of the optical element 3. As for such an irregularity pattern, for example, there is a grating pattern that can diffract the light 10 so that it is emitted from the inside to the outside of the optical element 3. Specifically, such a grating pattern can be a line-and-space pattern in which inclined protrusions are arranged periodically.

[0029] Furthermore, as shown in Figure 1, the optical system of the present invention may also be provided with a light detection means 5 for detecting the light 10 extracted by the light extraction unit 21 or the light extraction unit 31. The light detection means 5 can be any means that can detect the light 10 from the light irradiation means 1 transmitted through the light extraction unit 21 or the light extraction unit 31 and convert information regarding the start time of irradiation of the light 10 into digital data. For example, existing image sensors such as CMOS (complementary metal-oxide-semiconductor) or CCD (charge-coupled device) can be used as the light detection means 5. As a result, the acquired information is converted into digital data, enabling data processing that accurately reflects the state of the light 10.

[0030] Furthermore, the optical system of the present invention may have a waveguide 4 connecting the light extraction unit 21 or the light extraction unit 31 and the light detection means 5, as shown in Figure 1 or Figure 2. The waveguide 4 is a path for light 10 that has a mechanism to confine light 10 by total internal reflection and propagate it in a specific direction by sandwiching a medium with a high refractive index between a medium with a low refractive index. By connecting the light extraction unit 21 or the light extraction unit 31 and the light detection means 5 with the waveguide 4, even if the distance between the light extraction unit 21 or the light extraction unit 31 and the light detection means 5 is long, light 10 can be guided efficiently without attenuation. In addition, light 10 becomes less susceptible to the influence of the external environment, and light 10 can be accurately detected by the light detection means 5.

[0031] Furthermore, as shown in Figure 3, the optical system of the present invention may also be provided with a light detection means 6 that detects the reflected light of the light 10 that has passed through the optical element 3 from the light irradiation means 1. The light detection means 6 detects the reflected light that has hit an object 9, been reflected, and returned from the light 10 that has been irradiated from the light irradiation means 1 and passed through the optical element 3, and converts information such as its position and light intensity into digital data. Here, the object 9 can be anything that can be detected by the light detection means 6, and can include various things such as living organisms and objects, depending on the measurement purpose of the optical system. For example, when the optical system of the present invention is applied as a collision prevention system when an automobile is in motion, the object 9 can be other vehicles (cars, motorcycles, bicycles), pedestrians, animals, or fixed objects (utility poles, walls, curbs, etc.). The light detection means 6 can be anything that can detect reflected light and convert it into digital data. For example, existing image sensors such as CMOS (complementary metal-oxide-semiconductor) or CCD (charge-coupled device) can be used as the light detection means 5.

[0032] Furthermore, as shown in Figure 4, it is also possible to share the light detection means 6 as a substitute for the light detection means 5. This allows for easy measurement of the distance to the object from the time difference between the two sets of data. It also enables the consolidation of functions in the optical system and cost reduction.

[0033] Furthermore, when the optical system of the present invention is used in a bright environment such as outdoors, there is a problem that unwanted light enters the light detection means, reducing the accuracy of light detection. Therefore, the optical system of the present invention may be equipped with a bandpass filter 8 that suppresses light other than the wavelength band irradiated by the light irradiation means 1 from entering the light detection means 5 and light detection means 6. This allows for accurate measurement of the light 10 in the wavelength band irradiated by the light irradiation means 1, enabling stable measurement regardless of ambient light conditions. The bandpass filter 8 can be any conventionally known and well-known type, as long as it can suppress unwanted light other than the wavelength band irradiated by the light irradiation means 1 from entering the light detection means. Also, the bandpass filter 8 can be placed anywhere as long as it can suppress unwanted light from entering the light detection means. For example, the bandpass filter 8 may be placed directly in front of the light detection means 5 or light detection means 6, or it may be placed on the incident side or the outgoing side of the light extraction unit 21 or light extraction unit 31.

[0034] Furthermore, as shown in Figure 3, the optical system of the present invention may further include a calculation means 7 that calculates the distance to the object 9 based on information from the light detection means 5 and the light detection means 6. The calculation means 7 may calculate the distance to the object 9 in any way, but for example, the distance between the optical element 12 and the object 9 can be calculated from the time from when the light 10 irradiated from the light irradiation means 1 is reflected by the object 9 and received by the light detection means 6. The irradiation start time when the light irradiation means 1 irradiates the light 10 can be calculated from the timing when the light detection means 5 receives the light 10, as described above.

[0035] 1. Light irradiation means 2. Housing 21. Light extraction unit 22. Waveguide 25. Light irradiation means set unit 26. Optical element set unit 3. Optical element 31. Light extraction unit 4. Waveguide 5. Light detection means 6. Light detection means 7. Calculation means 8. Bandpass filter 9. Object 10. Light

Claims

1. An optical system comprising a light irradiation means capable of irradiating light, an optical element that exhibits an optical function with respect to the light, and a housing that encloses the light irradiation means together with the optical element, wherein the housing has a light extraction section for extracting the light from the light irradiation means to a predetermined position.

2. The optical system according to claim 1, characterized in that the light extraction unit is located outside the range of the light emission angle of the light irradiation means.

3. An optical system comprising a light irradiation means capable of irradiating light, an optical element that performs an optical function with respect to the light, and a housing that encloses the light irradiation means together with the optical element, wherein the optical element has a light extraction section for extracting light that has propagated inside the optical element from the light irradiation means to the outside.

4. The optical system according to any one of claims 1 to 3, further comprising a light detection means for detecting the light extracted by the light extraction unit.

5. The optical system according to claim 4, further comprising a waveguide connecting the light extraction unit and the light detection means.

6. The optical system according to claim 4, further comprising a bandpass filter that suppresses light other than the wavelength band irradiated by the light irradiation means from entering the light detection means.

7. The optical system according to any one of claims 1 to 3, further comprising a light detection means for detecting reflected light from the light irradiated by the light irradiation means that has passed through the optical element.

8. A housing for use in an optical system according to any one of claims 1 to 3, characterized by having a light irradiation means set section for arranging a light irradiation means, an optical element set section for arranging an optical element, and a light extraction section for extracting light from the light irradiation means to the outside.

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