OPTICAL DEVICE, PROJECTOR, AND METHOD OF PRODUCING OPTICAL DEVICE

• US 20150293271A1
• Filed: 06/25/2015
• Published: 10/15/2015
• Est. Priority Date: 12/28/2012
• Status: Active Grant

• Current Assignee: AGC, Inc.
• Original Assignee: Asahi Glass Company, Limited (AGC, Inc.)
• Inventors: MIYASAKA, Koji, YAMASHITA, Shuichi
• Granted Patent: US 9,939,561 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G02B 3/0037 characterized by the distribution or form of lenses
• CPC Class Codes: G02B 5/02 Diffusing elements; Afocal elements
• CPC Class Codes: G02B 5/0215 the surface having a regular structure
• CPC Class Codes: G02B 5/0221 the surface having an irregular structure G02B5/0226 takes precedence
• CPC Class Codes: G02B 5/0226 having particles on the surface
• CPC Class Codes: G02B 5/0231 the surface having microprismatic or micropyramidal shape macroscopic prism arrays G02B5/045
• CPC Class Codes: G02B 5/0268 characterized by the fabrication or manufacturing method
• CPC Class Codes: G02B 5/0278 used in transmission
• CPC Class Codes: G03B 21/005 Projectors using an electronic spatial light modulator but not peculiar thereto
• CPC Class Codes: G03B 21/2033 LED or laser light sources
• CPC Class Codes: G03B 21/204 using secondary light emission, e.g. luminescence or fluorescence using different colours G03B33/00; if related to video signals H04N9/3197
• CPC Class Codes: G03B 21/208 Homogenising, shaping of the illumination light
• CPC Class Codes: G03B 33/06 by additive-colour projection apparatus
• CPC Class Codes: G03B 33/12 using beam-splitting or beam-combining systems, e.g. dichroic mirrors
• CPC Class Codes: H04N 9/3152 for shaping the light beam beam shaping per se G02B27/09

Abstract

An optical device includes a base material including a surface on which multiple concaves are formed. The concaves include respective curved surfaces. The concaves are formed so that the bottoms of the concaves are at two or more different positions in a depth direction. In the optical device, 2/7≦|(n1−n2)×Δd|/λ≦10 holds, where n1 is the refractive index of the base material, n2 is the refractive index of a medium around the concaves, λ is the wavelength of a beam flux that enters the base material, and Δd is a range of the positions of the bottoms in the depth direction.

Claims

1. An optical device, comprising:

a base material including a surface on which a plurality of concaves are formed,

wherein the concaves include respective curved surfaces,

the concaves are formed so that bottoms of the concaves are at two or more different positions in a depth direction, and

2/7≦

|(n1−

n2)×

Δ

d|/λ

≦

10 holds, where n1 is a refractive index of the base material, n2 is a refractive index of a medium around the concaves, λ

is a wavelength of a beam flux that enters the base material, and Δ

d is a range of the positions of the bottoms in the depth direction.

2. The optical device as claimed in claim 1, wherein the optical device transmits light.

3. The optical device as claimed in claim 1, wherein the bottoms are arranged at predetermined intervals.

4. The optical device as claimed in claim 1, wherein

the bottoms are irregularly formed, and

each of the irregularly formed bottoms is within a corresponding one of regions bounded by bisectors of adjacent ones of points corresponding to the bottoms in a case where the bottoms are arranged at predetermined intervals.

5. The optical device as claimed in claim 1, wherein the bottoms include respective flat surfaces.

6. The optical device as claimed in claim 5, wherein the flat surfaces are of two or more different sizes.

7. A projector, comprising:

the optical device as set forth in claim 1; and

a light source that emits light that enters the optical device.

8. An optical device, comprising:

a base material including a surface on which a plurality of convexes are formed,

wherein the convexes include respective curved surfaces,

the convexes are formed so that tops of the convexes are at two or more different positions in a height direction, and

2/7≦

|(n1−

n2)×

Δ

d|/λ

≦

10 holds, where n1 is a refractive index of the base material, n2 is a refractive index of a medium around the convexes, λ

is a wavelength of a beam flux that enters the base material, and Δ

d is a range of the positions of the tops in the height direction.

9. The optical device as claimed in claim 8, wherein the optical device transmits light.

10. The optical device as claimed in claim 8, wherein the tops are arranged at predetermined intervals.

11. The optical device as claimed in claim 8, wherein

the tops are irregularly formed, and

each of the irregularly formed tops is within a corresponding one of regions bounded by bisectors of adjacent ones of points corresponding to the tops in a case where the tops are arranged at predetermined intervals.

12. The optical device as claimed in claim 8, wherein the tops include respective flat surfaces.

13. The optical device as claimed in claim 12, wherein the flat surfaces are of two or more different sizes.

14. A projector, comprising:

the optical device as set forth in claim 8; and

a light source that emits light that enters the optical device.

15. A projector, comprising:

a light source that emits laser light;

a microlens array including a plurality of lens parts formed on a surface thereof through which the laser light enters the microlens array;

a spatial modulator illuminated with a beam flux of the laser light transmitted through the microlens array; and

a projection optical system that projects the beam flux from the spatial modulator,

wherein sin δ

>

2λ

/P>

6λ

/D is satisfied, where λ

is a wavelength of the laser light, D is a diameter of the beam flux of the laser light that enters the microlens array, δ

is an angle of divergence of the microlens array, and P is an adjacent lens part pitch of the microlens array.

16. The projector as claimed in claim 15, wherein sin η

>

λ

/2P is satisfied, where η

is a spread angle of the laser light that enters the microlens array.

17. The projector as claimed in claim 15, wherein surface roughness of the lens parts of the microlens array is 100 nm or less in Ra.

18. The projector as claimed in claim 15, wherein

intensity of the laser light emitted onto the microlens array is 10 W or more, and

the microlens array is formed of a material having a coefficient of linear thermal expansion of 8.5×

10<sup>−

6</sup>K<sup>−

1</sup> or less.

19. The projector as claimed in claim 15, wherein the microlens array is formed of a material containing silicon oxide.

20. A projector, comprising:

a light source that emits laser light;

a microlens array including a plurality of lens parts formed on a surface thereof through which the laser light enters the microlens array;

a spatial modulator illuminated with a beam flux of the laser light transmitted through the microlens array; and

a projection optical system that projects the beam flux from the spatial modulator,

wherein at least one of an aperture size, a radius of curvature, and a pitch of the lens parts differs between adjacent ones of the lens parts in the microlens array.

21. The optical device as claimed in claim 20, wherein the at least one of the aperture size, the radius of curvature, and the pitch has a variation of ±

10% or less relative to a reference value.

22. The projector as claimed in claim 20, wherein surface roughness of the lens parts of the microlens array is 100 nm or less in Ra.

23. The projector as claimed in claim 20, wherein

intensity of the laser light emitted onto the microlens array is 10 W or more, and

the microlens array is formed of a material having a coefficient of linear thermal expansion of 8.5×

10<sup>−

6</sup>K<sup>−

1</sup> or less.

24. The projector as claimed in claim 20, wherein the microlens array is formed of a material containing silicon oxide.