Abstract: The present disclosure relates to a lens optical system, a light receiving device, and a distance measuring system capable of providing a highly efficient lens optical system while achieving reduction in size and height. A lens optical system includes, in order from an object side, a first lens group having a negative refractive power, and a second lens group having a positive refractive power, in which the first lens group includes a first lens having a negative refractive power, the second lens group includes a second lens having a positive or negative refractive power, a third lens having a positive refractive power, and a fourth lens having a positive refractive power, and the lens optical system has a positive refractive power as a whole. The present disclosure can be applied to, for example, a distance measuring system that detects a distance to a subject in a depth direction, and the like.

Abstract: An image can be projected in a wide angular range while an increase in a beam diameter is suppressed. A light source device according to the present disclosure includes: a plurality of light emitting elements divided into a plurality of regions; and an optical unit that includes a plurality of first lens groups having a first focal length and corresponding to the regions of the light source unit on a one-to-one basis, and a second lens group having a second focal length and emitting light having passed through the first lens groups. In the optical unit, for each of the regions, the first focal length is smaller than zero, the second focal length is larger than zero, and each composite focal length of each of the first lens groups and the second lens group is larger than the second focal length.

Abstract: An imaging apparatus with reduced flare includes an imaging structure including a solid state imaging element (1) and a transparent substrate (2) disposed on the imaging element. The imaging apparatus includes a circuit substrate (7) including a circuit, a spacer (10) including at least one fixing portion (11) that guides the imaging structure to a desired position on the circuit substrate (7) when the imaging structure is mounted on the circuit substrate, and a light absorbing material (13) disposed on at least one side surface of the imaging structure such that that light absorbing material (13) is between the imaging structure and the at least one fixing portion.

Abstract: [Object] Provided are a light receiving device and a light receiving circuit that are capable of performing highly accurate ranging with an increased field of view (FOV). [Solving Means] A light receiving device according to the present disclosure includes a light detector array including a plurality of pixels each configured to output a pulse in response to a reaction of a light detector with a photon, a counter circuit configured to count the pulse outputted from at least one of the pixels of the light detector array, and a control circuit configured to select, from the light detector array, one of the pixels to be enabled and one of the pixels to be disabled, on the basis of the number of counts of the pulse from the counter circuit.

Abstract: An image projection system according to the present disclosure includes a projection optical system and an eyepiece optical system. The projection optical system projects an image. The eyepiece optical system is configured separately from the projection optical system and is to be mounted on a head of a viewer. The eyepiece optical system includes at least one holographic element. The eyepiece optical system guides projection light from the projection optical system to a pupil of the viewer. The holographic element deflects first-order diffracted light toward the pupil of the viewer, and has a positive focal length for the first-order diffracted light. At a time of viewing of the image, the projection light enters the eyepiece optical system at an angle that is equal to or larger than ? expressed by the following expression, ?=arctan((3.

Abstract: Disclosed herein is a lens module for a projector of laser scanning type which is focus-free and has a short throw distance. In one example, a lens module includes a first optical member including a free-curved lens that passes a beam light reflected by a minute vibrating mirror; and a second optical member including a free-curved mirror to reflect the beam light which has passed through the first optical member, or a free-curved lens to pass the beam light which has passed through the first optical member. The beam light, which has been reflected by or has passed through the second optical member, has at the same position beam waists in horizontal and vertical directions perpendicular to a propagating direction of the beam light and also has beam radii coinciding in the horizontal and vertical directions.

Abstract: A projection optical system according to the present disclosure includes, in order from a side on which a light source is located to a projection side along an optical axis: a first lens group that includes one or more lenses, has a positive focal length, and condenses light from the light source on a primary image-forming point that is an image of the light source; a deflector that scans light from the first lens group; and a second lens group that includes one or more lenses, has a positive focal length, and forms an image of light from the deflector at a position of a secondary image-forming point that is an image of the primary image-forming point, and the first lens group forms the primary image-forming point between the first lens group and the second lens group along the optical axis.

Abstract: An image projection system according to the present disclosure includes a projection optical system and an eyepiece optical system. The projection optical system projects an image. The eyepiece optical system is configured separately from the projection optical system and is to be mounted on a head of a viewer. The eyepiece optical system includes at least one holographic element. The eyepiece optical system guides projection light from the projection optical system to a pupil of the viewer. The holographic element deflects first-order diffracted light toward the pupil of the viewer, and has a positive focal length for the first-order diffracted light. At a time of viewing of the image, the projection light enters the eyepiece optical system at an angle that is equal to or larger than ? expressed by the following expression, ?=arc tan ((3.

Abstract: An imaging apparatus with reduced flare includes an imaging structure including a solid state imaging element (1) and a transparent substrate (2) disposed on the imaging element. The imaging apparatus includes a circuit substrate (7) including a circuit, a spacer (10) including at least one fixing portion (11) that guides the imaging structure to a desired position on the circuit substrate (7) when the imaging structure is mounted on the circuit substrate, and a light absorbing material (13) disposed on at least one side surface of the imaging structure such that that light absorbing material (13) is between the imaging structure and the at least one fixing portion.

Abstract: A projection optical system according to the present disclosure includes, in order from a side on which a light source is located to a projection side along an optical axis: a first lens group that includes one or more lenses, has a positive focal length, and condenses light from the light source on a primary image-forming point that is an image of the light source; a deflector that scans light from the first lens group; and a second lens group that includes one or more lenses, has a positive focal length, and forms an image of light from the deflector at a position of a secondary image-forming point that is an image of the primary image-forming point, and the first lens group forms the primary image-forming point between the first lens group and the second lens group along the optical axis.

Abstract: Disclosed herein is a lens module for a projector of laser scanning type which is focus-free and has a short throw distance. In one example, a lens module includes a first optical member including a free-curved lens that passes a beam light reflected by a minute vibrating mirror; and a second optical member including a free-curved mirror to reflect the beam light which has passed through the first optical member, or a free-curved lens to pass the beam light which has passed through the first optical member. The beam light, which has been reflected by or has passed through the second optical member, has at the same position beam waists in horizontal and vertical directions perpendicular to a propagating direction of the beam light and also has beam radii coinciding in the horizontal and vertical directions.

Abstract: Provided is an objective lens including a diffraction portion provided on a laser beam incident plane or output plane. The diffraction portion includes first second, and third diffraction regions, wherein first laser beams corresponding to a first optical disc having a first transmissive layer are condensed on a data recording portion of the first optical disc, second laser beams corresponding to a second optical disc having a second transmissive layer thicker than the first transmissive layer are condensed on a data recording portion of the second optical disc, and third laser beams corresponding to a third optical disc having a third transmissive layer thicker than the second transmissive layer are condensed on a data recording portion of the third optical disc. An evaluation parameter calculated on the basis of an in-plane efficiency distribution function has a value corresponding to a symbol error rate that is less than a predetermined value.

Abstract: Provided is an objective lens including a diffraction portion provided on a laser beam incident plane or output plane. The diffraction portion includes first second, and third diffraction regions, wherein first laser beams corresponding to a first optical disc having a first transmissive layer are condensed on a data recording portion of the first optical disc, second laser beams corresponding to a second optical disc having a second transmissive layer thicker than the first transmissive layer are condensed on a data recording portion of the second optical disc, and third laser beams corresponding to a third optical disc having a third transmissive layer thicker than the second transmissive layer are condensed on a data recording portion of the third optical disc. An evaluation parameter calculated on the basis of an in-plane efficiency distribution function has a value corresponding to a symbol error rate that is less than a predetermined value.