Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
  • G01C3/00—Measuring distances in line of sight; Optical rangefinders
  • G01C3/02—Details
  • G01C3/06—Use of electric means to obtain final indication
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
  • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
  • G01S7/481—Constructional features, e.g. arrangements of optical elements

Definitions

• the present invention relates to an optical system device.
• Three-dimensional measurement sensors using the time-of-flight (TOF) method are being adopted for mobile devices, cars, robots, and more. This measures the distance to an object from the time it takes for light irradiated from a light source to be reflected and returned. If the light from the light source is irradiated evenly onto a specified area of the object, the distance at each irradiated point can be measured, and the three-dimensional structure of the object can be detected.
• TOF time-of-flight
• in-vehicle sensors are used in obstacle detection and collision avoidance systems. They can improve safety by measuring the distance to objects around the car in real time and sending warnings to the driver as necessary. They also play an important role in autonomous driving technology. By accurately grasping the shape, position, and distance of surrounding objects and terrain, sensors can be used to estimate the vehicle's self-position and map the environment. This enables autonomous vehicles to drive safely and avoid obstacles. They are also used in parking assistance systems. Sensors measure the distance to surrounding objects and provide the driver with guidance to parking spaces and approaching warnings. They are useful for preventing collisions when parking and improving space efficiency.
• Such a sensor system consists of a light irradiation unit that shines light onto the target object, an imaging unit that detects the light reflected from each point on the target object, and a calculation unit that calculates the distance to the target object from the signal received by the imaging unit.
• the imaging unit and calculation unit can use existing CMOS imagers and CPUs, so the unique part of the above system is the light irradiation unit, which consists of a laser and an optical filter.
• the light irradiation unit which consists of a laser and an optical filter.
• Conventional light irradiation units for vehicle-mounted sensors have a problem with high energy consumption because they irradiate light over a wide area.
• To reduce energy consumption some systems use a system in which the light from the irradiation unit is scanned to irradiate the entire target object (for example, Patent Document 1).
• the present invention aims to provide an optical system device that has no moving parts and can irradiate light of the required intensity to the required range.
• the optical system device of the present invention is characterized by comprising a plurality of irradiation sections each of which emits a line-shaped light in the x direction and is arranged in the y direction perpendicular to the x direction, a lens that converts the light from the irradiation sections into light having a different elevation angle in the y direction for each irradiation section, a diffuser that spreads the light that has passed through the lens in the x direction, and a control section that controls the lighting of each of the irradiation sections.
• the lens converts the light from each of the irradiation sections into collimated light.
• the lens may also change the light from each of the irradiation units into different lights with equal elevation angles.
• the lens may be a cylindrical lens.
• the lens may also be a Fresnel lens.
• the control unit may also turn on the illumination units in sequence.
• the optical system device of the present invention may also include an imaging unit that detects light that is reflected back from an object from the light emitted by the irradiation unit, and a calculation unit that calculates the distance to the object based on information from the imaging unit.
• the optical system device of the present invention has no moving parts, making it possible to reduce its size and manufacturing costs.
• the irradiating parts are turned on in sequence to irradiate in a line, reducing energy consumption.
• FIG. 1 is a schematic cross-sectional view showing an optical system device of the present invention.
• 1 is a perspective view showing an optical system device according to the present invention
• FIG. 11 is a schematic plan view showing another optical system device of the present invention.
• 1 is a schematic plan view showing an optical system device of the present invention.
• 1 is a diagram showing a light distribution in the far field for each irradiation unit of the optical system device of the present invention.
• FIG. FIG. 4 is a diagram showing a light distribution in the y direction for each irradiation unit of the optical system device of the present invention.
• 3A and 3B are diagrams showing a light distribution in the far field and a planar projected image of an entire irradiation portion of the optical system device of the present invention.
• the optical system device of the present invention is mainly composed of multiple irradiation units 1, a lens 2, a diffuser 3, and a control unit 4.
• the irradiation unit 1 is for irradiating the lens 2 with light. If the optical axis direction of the irradiation unit 1 is the z direction, the irradiation unit 1 irradiates a line of light in the x direction perpendicular to the z direction. Furthermore, multiple irradiation units 1 are arranged in the y direction perpendicular to the x and z directions. Furthermore, each irradiation unit 1 can irradiate light independently.
• the irradiation unit 1 may be any type capable of irradiating the lens 2 with light, and may be, for example, a type consisting of multiple light sources arranged in the x direction. In this case, the light sources of one irradiation unit 1 may be in one row or multiple rows. Another irradiation unit may be one that irradiates light from the light source through linear slits in the x direction. The intensity of light in each irradiation unit may be the same or different. For example, in an optical system device in which light is reflected by an object 9 and returns to a camera, the intensity of the light returning to the camera decreases as the emission angle of the irradiated light increases.
• the light intensity may be increased for light with a larger emission angle.
• a specific example of the irradiation unit 1 is a VCSEL (Vertical Cavity Surface Emitting Laser), which can irradiate light in a direction perpendicular to the light-emitting surface and is expected to produce high output with little power.
• VCSEL Vertical Cavity Surface Emitting Laser
• the spacing between each of the irradiation units 1 can be determined in any way depending on the application, but a smaller spacing is preferable because it allows the size of the lens 2 and the diffuser 3 to be reduced. Specifically, the spacing between each of the irradiation units 1 can be set at a pitch of 100 to 200 ⁇ m.
• each irradiation unit 1 is formed on the same plane. More preferably, each irradiation unit 1 is all formed on the same semiconductor chip.
• a multi-emitter VCSEL having multiple light sources, in which each light source on a line in the x direction can be controlled independently, can be used. This makes it possible to eliminate the need to align the irradiation units in the x, y, and z directions when assembling the optical system device.
• the lens 2 is for changing the light from the irradiation unit 1 into light with a specified elevation angle in the y direction (angle with respect to the y axis in the zy plane).
• the lens 2 is also for changing the light into light with a different elevation angle for each irradiation unit 1. This makes it possible to irradiate light of the required intensity at the required angle without using any moving parts by turning on each irradiation unit 1 in the appropriate order.
• the irradiation unit 1 and lens 2 are positioned so that the optical axis direction of the irradiation unit 1 and the optical axis direction of the lens 2 are aligned. It is also preferable that the lens 2 change the light from each irradiation unit 1 into collimated light.
• the lens 2 may be of any type as long as it can change the light of the irradiation unit 1 into light with a different elevation angle in the y direction for each irradiation unit 1.
• the lens 2 can be a cylindrical lens.
• the angle of either or both of the entrance surface where the light enters the cylindrical lens and the exit surface where the light leaves the cylindrical lens can be adjusted to control the refraction direction so that the light of the irradiation unit 1 is changed into light with a different elevation angle in the y direction for each irradiation unit 1.
• the lens 2 can also be a cylindrical lens or other lens with a Fresnel lens shape.
• Figure 3 shows an example of a lens 2 with a Fresnel lens-shaped entrance surface and a flat exit surface.
• the lens 2 converts the light from each irradiation unit 1 into different light with equal elevation angles.
• the angle be such that the light from each irradiation unit 1 that passes through the lens 2 is filled in just the right amount.
• Lens 2 may be designed using a conventionally known method. Lens 2 may be made of any material, such as resin or glass.
• the diffuser 3 is for spreading the light transmitted through the lens 2 in the x direction. If the light transmitted through the lens 2 can be spread in the x direction, a well-known technology can be used. For example, a method using a diffractive optical element (DOE) or a method using a microlens array is known for the diffuser 3. In addition, an optical element with good light efficiency and suppressed uneven light distribution, such as the optical element described in WO2023/032094A1, may be used.
• the diffuser 3 may spread the transmitted light in the x direction so that the intensity of the light is uniform, or may change the intensity of the light in a specific direction on the line.
• the diffuser 3 may be made of any material, but may be made of resin or glass, for example.
• the optical system device of the present invention may also have an imaging section 5 that detects light emitted by the irradiation section 1 that is reflected back from the object 9.
• the imaging section 5 is for converting information such as the position and light intensity of the detected light into digital data.
• the imaging section 5 may be any type that can detect reflected light and convert that information into digital data, and for example, an existing image sensor such as a CMOS or CCD may be used.
• the imaging section 5 may also be formed on the same semiconductor chip together with the above-mentioned irradiation section 1.
• the optical system device of the present invention may further include a calculation unit 6 that calculates the distance to the object 9 based on information from the imaging unit 5.
• the distance to the object 9 means the distance between the object 9 and references such as the irradiation unit 1 and the imaging unit 5.
• the calculation unit 6 may calculate the distance to the object 9 in any way, but for example, the distance between the irradiation unit 1 and the object 9 can be calculated from the time it takes for the light irradiated from the irradiation unit 1 to be reflected by the object 9 and received by the imaging unit 5.
• the optical system device used had 14 irradiation units 1 that irradiate linear light in the x direction, arranged in the y direction with a pitch of 140 ⁇ m.
• the linear light irradiated by the irradiation units 1 had a length in the y direction of 130.0 ⁇ m and a length in the x direction of 6700 ⁇ m.
• the lens 2 used in the optical system device was one that changed the light from each irradiation unit 1 into different light with equal elevation angles of 1.875 degrees in the y direction in the order of the irradiation units 1.
• the diffuser 3 used in the optical system device was one that spread the light transmitted through the lens 2 in the x direction so that the irradiation angle was 90 degrees.
• the optical simulation software LightTools manufactured by Synopsys was used for the simulation.
• FIG. 7 shows (a) the light distribution in the far field and (b) the planar projection image when the entire irradiation section is illuminated. It can be seen that uniform light is irradiated in the x and y directions. Therefore, it is possible to irradiate light over the entire required range depending on the situation.

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• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• General Physics & Mathematics (AREA)
• Radar, Positioning & Navigation (AREA)
• Remote Sensing (AREA)
• Electromagnetism (AREA)
• Computer Networks & Wireless Communication (AREA)
• Measurement Of Optical Distance (AREA)
• Length Measuring Devices By Optical Means (AREA)

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Cited By (1)

Citations (7)

• 2024
  • 2024-07-03 JP JP2025531586A patent/JPWO2025009577A1/ja active Pending
  • 2024-07-03 CN CN202480042811.XA patent/CN121399495A/zh active Pending
  • 2024-07-03 WO PCT/JP2024/024153 patent/WO2025009577A1/ja not_active Ceased

Patent Citations (7)

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