Scanning optical system and scanning device

1. A scanning optical system comprising:

a scanner that deflects laser light from a light source while changing a deflection angle of the laser light;

a light splitting unit that is capable of splitting-off the laser light from an optical path of the laser light deflected by the scanner;

an optical-path combining unit that is disposed between the light source and the scanner and that causes the laser light split-off by the light splitting unit to travel toward the scanner; and

a reentry relay optical system that has one time magnifying power and that is disposed between the light splitting unit and the optical-path combining unit, the reentry relay optical system relaying the laser light split-off by the light splitting unit so as to cause the laser light to be incident again on the scanner at the same position as an incident position of the laser light from the light source via the optical-path combining unit.

2. The scanning optical system according to claim 1 , further comprising:

a polarizing element that is disposed in an optical path between the scanner and the light splitting unit or in an optical path between the optical-path combining unit and the scanner and that changes a polarization direction of the laser light,

wherein the light splitting unit and the optical-path combining unit are polarization beam splitters.

3. The scanning optical system according to claim 1 , further comprising:

a pupil-projection relay optical system capable of relaying the laser light deflected again by the scanner to an objective lens.

4. The scanning optical system according to claim 3 , further comprising:

a magnification relay optical system that increases a beam diameter of the laser light deflected again by the scanner and relays the laser light to the pupil-projection relay optical system.

5. The scanning optical system according to claim 1 ,

wherein the scanner includes a first scanner mirror and a second scanner mirror that are swivelable about swivel axes intersecting each other and that are disposed adjacent to each other.

6. The scanning optical system according to claim 1 ,

wherein the scanner includes a first scanner mirror and a second scanner mirror that are swivelable about swivel axes intersecting each other and that are disposed adjacent to each other, and

wherein the scanning optical system further comprises an inter-scanner-mirror relay optical system that is disposed between the first scanner mirror and the second scanner mirror and that relays laser light deflected by the first scanner mirror to the second scanner mirror.

7. A scanning device comprising:

two scanning optical systems according to claim 1 ; and

an inter-scanner relay optical system disposed between the two scanning optical systems,

wherein the scanner in one of the scanning optical systems is a first scanner that deflects the laser light in a first direction,

wherein the scanner in the other scanning optical system is a second scanner that deflects the laser light in a second direction orthogonal to the first direction, and

wherein the inter-scanner relay optical system relays the laser light deflected by the first scanner to the second scanner.