The present disclosure describes a system and method for coaxial LiDAR scanning. The system includes a first light source configured to provide first light pulses. The system also includes one or more beam steering apparatuses optically coupled to the first light source. Each beam steering apparatus comprises a rotatable concave reflector and a light beam steering device disposed at least partially within the rotatable concave reflector. The combination of the light beam steering device and the rotatable concave reflector, when moving with respect to each other, steers the one or more first light pulses both vertically and horizontally to illuminate an object within a field-of-view; obtain one or more first returning light pulses, the one or more first returning light pulses being generated based on the steered first light pulses illuminating an object within the field-of-view, and redirects the one or more first returning light pulses.

A scanning optical system, includes a mirror unit having a first mirror surface and a second mirror surface which incline to a rotation axis; and a light projecting system having a light source. A light flux emitted from the light source is reflected on the first mirror surface of the mirror unit, thereafter, reflected on the second mirror surface, and then, projected so as to scan in a main scanning direction onto an object in accordance with rotation of the mirror unit. The light flux emitted from the second mirror surface becomes a plurality of spot lights on the object side, and the plurality of spot lights are arranged along a direction intersecting with the main scanning direction.

An optical scanning device includes a deflector for deflecting a light beam to optically scan a scanned region on a scanned surface in a main scanning direction, and an imaging optical system for guiding the light beam deflected by the deflector, to the scanned surface. The imaging optical system includes an imaging optical element in which, in the main scanning direction, a distance to an optical axis from one effective end portion through which a light beam that enters one end portion of the scanned region passes is longer than a distance to the optical axis from another effective end portion through which a light beam that enters another end portion of the scanned region passes. In the imaging optical element, a thickness in an optical axis direction of the one effective end portion is thinner than a thickness in the optical axis direction of the other effective end portion.

A scanning optical system, includes a mirror unit equipped with a first mirror surface and a second mirror surface each of which inclines to a rotation axis; and a light projecting system which includes at least one light source to emit a light flux toward the first mirror surface. A light flux emitted from the light source is reflected on the first mirror surface of the mirror unit, thereafter, reflected on the second mirror surface, and then, projected so as to scan in a main scanning direction onto an object in accordance with rotation of the mirror unit, and in a case where a direction included in a main scanning plane is set to 0 degree, the light flux reflected on the second mirror surface is polarized in a range within an angle of ±30 degrees to the main scanning plane.

A scanning optical device proposed herein includes first and second semiconductor lasers, first and second coupling lenses, a polygon mirror, and first and second holders. The first and second coupling lenses convert light emitted by the first and second semiconductor lasers into light beams, respectively. The polygon mirror deflects the light beams received from the first and second coupling lenses. The first holder has a seating surface on which the first coupling lens is fixed by a photo-curable resin. The second holder is configured to hold the second coupling lens in such a position that the first and second coupling lenses are arranged in a line parallel to a rotation axis of the polygon mirror. The second holder is fixed to the first holder by a photo-curable resin.

A scanning optical device includes a light source, a polygon mirror, a motor, a scanning optical system, a frame, and a seating surface. The scanning optical system comprises a first scan lens, a second scan lens, and a reflecting mirror. The reflecting mirror is arranged to reflect a light beam toward the second scan lens. The reflecting mirror is supported on the seating surface. The seating surface allows adjustment of an angle of the reflecting mirror. The reflecting mirror reflects the light beam in a direction from the base wall toward the open side. A part of the reflecting mirror that overlaps the seating surface as viewed in a direction of thickness of the reflecting mirror is exposed to an outside of the frame and accessible from a side of the frame opposite to an open side of the frame.

A scanning optical device includes a semiconductor laser, a coupling lens, a condenser lens, a deflector, a scanning optical system, a frame, and a first cover. The coupling lens converts light emitted by the first semiconductor laser to a light beam. The light beam received from the coupling lens is concentrated through the condenser lens. The deflector includes a polygon mirror configured to deflect the light beam received from the condenser lens. The scanning optical system directs the light beam deflected by the deflector toward an image plane. The deflector and the scanning optical system are fixed to the frame. The first cover covers at least a portion of the frame on which the deflector is located. The frame includes a wall having an opening through which a light beam traveling toward the polygon mirror passes. The condenser lens closes the opening.

An optical scanning apparatus of the present invention includes: a splitting element which splits a light flux emitted from a light source into first and second light fluxes; a deflecting unit which deflects the first and second light fluxes to scan first and second scanned surfaces in a main scanning direction; and an imaging optical system which includes a first imaging lens on which both the first and second light fluxes deflected by the deflecting unit are incident and guides the first and second light fluxes to the first and second scanned surfaces. The condition expressed by

−1.1≦α1/α2≦−0.9

is satisfied where α1 and α2 are angles within a main scanning cross section between a first axis parallel to the main scanning cross section and directions of incidence of the first and second light fluxes on the deflecting unit, respectively.

A light scanning device includes a light source, a deflector, a reflection mirror, and a light width regulating portion. The light source includes a plurality of light-emitting elements located at intervals one another. The deflector deflects to scan by reflecting a plurality of light beams. The plurality of light beams are emitted from the respective light-emitting elements. The reflection mirror is located in an optical path between the light source and the deflector and guides the plurality of light beams emitted from the plurality of light-emitting elements to the deflector. The light width regulating portion regulates widths of the plurality of light beams reflected by the reflection mirror in a main-scanning direction. The light width regulating portion is located adjacent to a reflecting surface of the reflection mirror and includes a pair of regulating wall portions located opposed one another in the main-scanning direction.

A scanning unit includes a light source controllable to emit a light beam; a scanning mirror having a plurality of reflective surfaces, the scanning mirror receiving the light beam from the light source and deflecting at least portions of the light beam along a scan direction; and a collimator lens disposed between the light source and the scanning mirror, the collimator lens having a light incident surface that is spherical and a light exit surface that is aspheric such that the light beam, after passing through the collimator lens, is diverged by the collimator lens so as to be incident on at least two reflective surfaces of the scanning mirror.