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EP-3581844-B1 - LASER ILLUMINATION DEVICE AND PERIPHERAL MONITORING SENSOR PROVIDED WITH SAME

EP3581844B1EP 3581844 B1EP3581844 B1EP 3581844B1EP-3581844-B1

Inventors

  • YAMAMOTO, KAZUO

Dates

Publication Date
20260506
Application Date
20171116

Claims (8)

  1. A laser illumination device (10, 210, 310, 410, 510, 610, 710), comprising: a light source component (11) configured to emit a laser beam (B1); a micro-element lens (12, 112, 312, 512, 712) configured to spread out the laser beam (B1), wherein the micro-element lens (12, 112, 312, 512, 712) is a lens array including a plurality of micro-lenses (12a, 112a, 312a, 512a, 712a) disposed in an incident plane; and a lens unit (13, 313, 613), that further expands the laser beam (B1) that has already been expanded by the micro-element lens, that has an incident face (13a, 313a) on which the laser beam (B1) is incident from the micro-element lens (12, 112, 312, 512, 712), and an emission face (13b, 313b) provided on an opposite side from the incident face (13a, 313a) and including a convex shape, the lens unit (13, 313, 613) having negative power to spread out the laser beam (B1) incident from the micro-element lens (12, 112, 312, 512, 712) wherein the micro-element lens (12, 112, 312, 512, 712) and/or the lens unit (13, 313, 613) includes diffusion particles configured to spread out an incident laser beam (B1).
  2. The laser illumination device according to Claim 1, wherein the micro-lenses (12a, 112a, 312a, 512a, 712a) included in the micro-element lens (12, 112, 312, 512, 712) have a curvature in which a distal end portion in an optical axis direction has a curvature larger than that of a periphery in a cross-sectional view parallel to an optical axis.
  3. The laser illumination device according to Claim 1 or 2, wherein the micro-lenses (12a, 112a, 312a, 512a, 712a) included in the micro-element lens (12, 112, 312, 512, 712) are cylindrical lenses.
  4. The laser illumination device according to any of Claims 1 to 3, wherein the incident face (13a, 313a) of the lens unit (13, 313, 613) has a concave shape.
  5. The laser illumination device according to any of Claims 1 to 4, wherein the lens unit (13, 313, 613) is a meniscus lens.
  6. The laser illumination device according to any of Claims 1 to 5, further comprising a beam expander (214) that is configured to combine a plurality of lenses disposed between the light source component (11) and the micro-element lens (12, 112, 312, 512, 712), and configured to expand the beam diameter of the laser beam (B1) emitted from the light source component (11).
  7. The laser illumination device according to any of Claims 1 to 6, further comprising a diffuser disposed between the micro-element lens (12, 112, 312, 512, 712) and the lens unit (13, 313, 613), the diffuser configured to spread out an incident laser beam (B1).
  8. A peripheral monitoring sensor (100), comprising: the laser illumination device (10, 210, 310, 410, 510, 610, 710) according to any of Claims 1 to 7; a light receiver configured to receive reflected light of the laser beam (B1) emitted from the laser illumination device (10, 210, 310, 410, 510, 610, 710), from a plurality of directions; and a detector (103) configured to detect surrounding objects on the basis of the amount and direction of the reflected light received by the light receiver.

Description

TECHNICAL FIELD The present invention relates to a laser illumination device and a peripheral monitoring sensor provided with the same. BACKGROUND Laser illumination devices in which a laser beam is used as the light source have been used in recent years for the illumination of vehicular peripheral monitoring sensors, and of monitoring sensors that monitor people in hospitals, factories, facilities, and the like. These laser illumination devices need to enlarge the beam spread of the laser beam and irradiate a wide angle (such as 140 degrees) in order to monitor as wide an area as possible by means of the laser beam emitted from a single light source. For this reason, a diffuser such as a lens array or a diffuser plate for diffusing light, for example, has been used as a means for diffusing laser light. However, with a configuration in which a diffuser is used, there is a limit to how efficiently the laser beam can be widened. For example, Patent Literature 1 discloses a laser illumination device comprising a micro-element lens, a light diffusing element, and the like as a configuration for diffusing a laser beam over a wide angle. Further, WO 2016/125384 A1 discloses an irradiation optical system including a uniformizing section and an irradiation lens section. The uniformizing section brings in-plane distribution of light emitted from a light source close to uniform in-plane distribution. The irradiation lens section diffuses the light in a predetermined direction. The in-plane distribution of the light is brought close to the uniform in-plane distribution by the uniformizing section. The irradiation lens section includes, in order from the light source, a first cylindrical lens and a second cylindrical lens each having negative refractive power in the predetermined direction. Moreover, CN 104 953 465 A discloses a diode laser matrix beam uniformizing device based on spatial frequency spectrum segmentation process. The device is capable of realizing beam shaping of planar array type laser diode arrays to obtain large-area uniform light spots. Additionally, EP 2256 458 A1 and US 6 069 748 A disclose laser line generators. CITATION LIST PATENT LITERATURE Patent Literature 1: WO 2008-114502 SUMMARY TECHNICAL PROBLEM However, the following problems are encountered with the conventional laser illumination device discussed above. That is, with the laser illumination device disclosed in the above publication, the laser beam emitted from the laser light source is spread out mainly using the micro-element lens and the light diffusing element, so there is a limit to how wide the irradiation range of the laser beam can be. Since a laser beam can cause damage when focused on the retina, there are safety standards for laser products. These safety standards have been set for, for example, in JIS C6802 (JIS: Japanese Industrial Standards), IEC60825 (IEC: International Electrotechnical Commission), and FDA1040 (FDA: US Food & Drug Administration). When a laser illumination device is applied to a vehicular peripheral monitoring sensor, the laser beam irradiates a wide area outdoors, so it needs to have no effect on the human body when used. The conventional laser illumination device discussed above is installed in a projector or another such image display device, and is configured to project an image on a projection screen via a light modulation element. That is, the goal is to irradiate the projection screen with the laser light, and since it is not assumed that the laser will be directed at a person, no consideration whatsoever is given to the safety of the human eye against the laser light. It is an object of the present invention to provide a laser illumination device capable of diffusing an emitted laser light over a wider angle and ensuring the safety of the eyes of any people in the vicinity, as well as a peripheral monitoring sensor provided with this device. SOLUTION TO PROBLEM To solve the above object, the invention provides a laser illumination device according to claim 1 and a peripheral monitoring sensor according to claim 8. Embodiments of the invention are described in the dependent claims. The laser illumination device according to a first aspect comprises a light source component, a micro-element lens, and a lens unit. The light source component emits a laser beam. The micro-element lens spreads out the laser light. The lens unit has an incident face on which the laser beam is incident from the micro-element lens, and an emission face provided on the opposite side from the incident face and including a convex shape, and this lens unit has negative power to spread out the laser beam incident from the micro-element lens. Here, in a laser illumination device mounted on a peripheral monitoring sensor or the like, for example, laser light emitted from the light source component irradiates a wide angle of 100 degrees or more in a substantially horizontal direction using a micro-element lens and a lens unit, fo