Optical system, barrel, and optical instrument using

• US 9,250,362 B2
• Filed: 04/24/2012
• Issued: 02/02/2016
• Est. Priority Date: 04/26/2011
• Status: Active Grant

• Current Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Original Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Inventors: Okuno, Takeharu
• Primary Examiner(s): Chapel, Derek S
• Application Number:
  US13/454,148
• Publication Number:
  US 20120275027A1
• Time in Patent Office: 1,379 Days
• US Class Current: 1/1
• CPC Class Codes: G02B 1/115 Multilayers
• CPC Class Codes: G02B 1/118 having sub-optical wavelength surface structures designed to provide an enhanced transmittance, e.g. moth-eye structures
• CPC Class Codes: G02B 2207/107 Porous materials, e.g. for reducing the refractive index
• CPC Class Codes: G02B 7/025 using glue

Abstract

Provided is an optical system having at least two or more lenses, wherein at least one of the lenses comprises an anti-reflection film formed by a wetting method on a part of or the entirety of the light beam effective surface thereof, and wherein at least one of the lenses other than the lens comprising the anti-reflection film is fixed to the space between the lens and a barrel for holding the lens via an energy-curable resin to be filled therein.

Claims

1. An optical system comprising:

a plurality of optical elements including a first lens and a second lens; and

a barrel configured to hold the plurality of optical elements,

wherein the second lens includes an anti-reflection film formed on an optical surface thereof,

wherein the first lens is fixed to the barrel via an energy-curable resin,

wherein the energy-curable resin includes a first layer consisting of an epoxy-type UV-curable resin and a second layer consisting of an acrylic UV-curable resin or a silicone UV-curable resin adjacent to the first layer in an optical-axis direction, and

wherein the first layer is disposed on a side of the second lens in the optical-axis direction.

2. The optical system according to claim 1, wherein the epoxy-type UV-curable resin contains 10% by weight or more of an epoxy resin.

3. The optical system according to claim 2, wherein the epoxy-type UV-curable resin contains 0.5% by weight or more of silica.

4. The optical system according to claim 3, wherein the viscosity of an uncured epoxy-type UV-curable resin is in a range from 1 Pa·

s to 50 Pa·

s.

5. The optical system according to claim 1, wherein the second layer comes into contact with the barrel.

6. The optical system according to claim 1, wherein the anti-reflection film is formed by a wetting method.

7. The optical system according to claim 1, wherein the anti-reflection film has a fine concave-convex profile having an average pitch of 400 nm or less.

8. The optical system according to claim 7, wherein the anti-reflection film contains aluminum oxide.

9. The optical system according to claim 1, wherein the anti-reflection film contains fluoride microparticles or hollow silica microparticles.

10. The optical system according to claim 1, wherein:

the first lens is composed of lenses, including a concave lens, joined with each other or adjoin each other, and

wherein a value of t/D is 0.1 or less,

where “

D”

represents an outer diameter of the concave lens and “

t”

represents a central thickness thereof.

12. The optical system according to claim 1, wherein the first layer is disposed between the second layer and the anti-reflection film so that the second layer is spaced from the anti-reflection film.

13. The optical system according to claim 12, wherein the energy-curable resin does not contain acrylate monomers and methacrylate monomers.

14. The optical system according to claim 1, wherein the first lens and the second lens are arranged adjacent to each other.

11. An optical instrument comprising:

a camera; and

an optical system comprising;

a plurality of optical elements including a first lens and a second lens; and

a barrel configured to hold the plurality of optical elements,

wherein the second lens includes an anti-reflection film formed on an optical surface thereof,

wherein the first lens is fixed to the barrel via an energy-curable resin,

wherein the energy-curable resin includes a first layer consisting of an epoxy-type UV-curable resin and a second layer consisting of an acrylic UV-curable resin or a silicone UV-curable resin adjacent to the first layer in an optical-axis direction, and

wherein the first layer is disposed on a side of the second lens in the optical-axis direction.