Optical scanning device and optical scanning unit

1. An optical scanning device, comprising:

a mirror that oscillates to scan incident visible light,

wherein the mirror includes:

a substrate, and

a multi-layer film that reflects the visible light, said multi-layer film including a metal film formed on the substrate, and a reflection enhancing film stacked on the metal film.

2. The optical scanning device as claimed in claim 1 , wherein the reflection enhancing film includes a low-refractive index film stacked on the metal film and a high-refractive index film stacked on the low-refractive index film.

3. The optical scanning device as claimed in claim 1 , wherein the metal film includes silver.

4. The optical scanning device as claimed in claim 2 , wherein the low-refractive index film includes alumina, and the high-refractive index film includes titanium oxide.

5. The optical scanning device as claimed in claim 2 , wherein the mirror further includes a protective film stacked on the high-refractive index film.

6. The optical scanning device as claimed in claim 5 , wherein the protective film includes alumina.

7. The optical scanning device as claimed in claim 1 , wherein the reflection enhancing film is adapted for a laser beam with a wavelength greater than or equal to 400 nm and less than or equal to 700 nm.

8. The optical scanning device as claimed in claim 1 , wherein when an incident angle of 0 degrees is an angle of light entering an uppermost surface of the reflection enhancing film in a direction of a normal of the uppermost surface, the reflection enhancing film is adapted for the visible light whose incident angle is greater than 0 degrees and less than 50 degrees.

9. An optical scanning device, comprising:

a mirror that reflects a laser beam having a wavelength in a predetermined range and entering the mirror at an incident angle in a predetermined range; and

an actuator that causes the mirror to oscillate vertically or horizontally to scan the laser beam,

wherein the mirror includes a substrate, a metal film formed on the substrate, and a reflection enhancing film stacked on the metal film; and

wherein the reflection enhancing film is a dielectric multi-layer film including a low-refractive index film stacked on the metal film and a high-refractive index film stacked on the low-refractive index film.

10. The optical scanning device as claimed in claim 9 , wherein the metal film includes silver.

11. The optical scanning device as claimed in claim 9 , wherein the low-refractive index film includes alumina, and the high-refractive index film includes titanium oxide.

12. The optical scanning device as claimed in claim 9 , wherein the mirror further includes a protective film stacked on the high-refractive index film.

13. The optical scanning device as claimed in claim 12 , wherein the protective film includes alumina.

14. The optical scanning device as claimed in claim 9 , wherein the reflection enhancing film is adapted for the laser beam that has a wavelength greater than or equal to 400 nm and less than or equal to 700 nm.

15. The optical scanning device as claimed in claim 9 , wherein when an incident angle of 0 degrees is an angle of light entering an uppermost surface of the reflection enhancing film in a direction of a normal of the uppermost surface, the reflection enhancing film is adapted for the laser beam whose incident angle is greater than 0 degrees and less than 50 degrees.

16. An optical scanning unit, comprising:

the optical scanning device of claim 1 ;

a mirror controller that controls vertical or horizontal oscillation of the mirror; and

a driver that drives an actuator for causing the mirror to oscillate according to a control signal from the mirror controller.

17. An optical scanning unit, comprising:

the optical scanning device of claim 9 ;

a mirror controller that controls vertical or horizontal oscillation of the mirror; and

a driver that drives the actuator according to a control signal from the mirror controller.