Scanning optical system and radar

Patent metadata

Field	Value
Publication number	US-10649071-B2
Application number	US-201515517721-A
Country	US
Kind code	B2
Filing date	Oct 6, 2015
Priority date	Oct 7, 2014
Publication date	May 12, 2020
Grant date	May 12, 2020

Abstract

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.

First claim

The invention claimed is:

1. A scanning optical system, comprising:
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 including at least one light source to emit a light flux toward the first mirror surface,
wherein 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 within a main scanning plane onto an object in accordance with rotation of the mirror unit, and
wherein, where the main scanning plane is considered to be at 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.

2. The scanning optical system described in claim 1 , wherein the mirror unit scans a plurality of different positions parallel to the main scanning direction on the object side during one rotation.

3. The scanning optical system described in claim 1 , wherein the mirror unit includes a plurality of pairs of the first mirror surface and the second mirror surface, and an intersection angle between the first mirror surface and the second mirror surface in each pair is different from respective intersection angles of the other pairs.

4. The scanning optical system described in claim 1 , wherein the mirror unit includes a plurality of pairs of the first mirror surface and the second mirror surface, and the plurality of pairs includes at least two pairs which have the same intersection angle between the first mirror surface and the second mirror surface and at least one pair which has an intersection angle different from the intersection angle of the two pairs.

5. The scanning optical system described in claim 1 , further comprising:
a deflecting element which is disposed between the light source and the mirror unit and changes a proceeding direction of a light flux emitted from the light source.

6. The scanning optical system described in claim 1 , wherein the light source includes a plurality of light sources, and respective light fluxes emitted from the light sources have different incident angles to the first mirror surface on a cross section passing through the rotation axis.

7. The scanning optical system described in claim 1 , wherein a light flux emitted from the second mirror surface toward the object has a cross sectional shape which is perpendicular to the proceeding direction and is shaped longer in a sub-scanning direction than in a main scanning direction.

8. The scanning optical system described in claim 1 , further comprising:
a dustproof cover which is disposed so as to cover at least the second mirror surface and is able to transmit a light flux emitted from the second mirror surface,
wherein on a cross section which includes the rotation axis of the mirror unit and the center of a light flux emitted from the second mirror surface so as to pass through the dustproof cover, a tangential line passing on an intersection point between the dustproof cover and the center of the emitted light flux intersects at an angle c with the rotation axis of the mirror unit, and satisfies the following formula
10 degrees <an angle ε<70 degrees (1).

9. A radar, comprising:
the scanning optical system described in claim 1 , and
a light receiving system to receive reflected light rays of a light flux emitted from the scanning optical system.

Assignees

• Konica Minolta Inc

Inventors

• Ishikawa Ryouta
• Kogo Shoji

Classifications

• G02B26/129 Primary

  Systems in which the scanning light beam is repeatedly reflected from the polygonal mirror · CPC title

• G01S7/4817 Primary

  relating to scanning · CPC title

• G01S17/86

  Combinations of lidar systems with systems other than lidar, radar or sonar, e.g. with direction finders · CPC title

• G01S7/481

  Constructional features, e.g. arrangements of optical elements · CPC title

• G02B27/286

  for controlling or changing the state of polarisation, e.g. transforming one polarisation state into another (G02B5/3083 takes precedence; light guide coupling means utilising polarising elements G02B6/34) · CPC title