Optical element

• US 10,073,193 B2
• Filed: 06/30/2015
• Issued: 09/11/2018
• Est. Priority Date: 07/15/2014
• Status: Active Grant

• Current Assignee: Oji Holdings Corporation
• Original Assignee: Oji Holdings Corporation
• Inventors: Hongo, Koki, Shinotsuka, Kei, Dai, Kotaro, Kajita, Keiichi
• Primary Examiner(s): NGUYEN, THONG Q
• Application Number:
  US15/322,982
• Publication Number:
  US 20170146696A1
• Time in Patent Office: 1,169 Days
• CPC Class Codes: G02B 1/11 Anti-reflection coatings
• 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 27/0018 with means for preventing ghost images anti-reflection coatings G02B1/11
• CPC Class Codes: G02B 5/0231 the surface having microprismatic or micropyramidal shape macroscopic prism arrays G02B5/045

Abstract

An optical element including, on a substrate, an anti-reflection layer on multiple small concave protrusions, which have a modal pitch less than or equal to a wavelength of light in an environment where the optical element is to be used, are formed; in which 80% or more of the concave protrusions include one or more steps, and satisfy the following conditions: 0.12d≤w_s≤0.17d and 0.42h≤z_s≤0.52h, in which d is a diameter of the concave protrusions, h is a depth of the concave protrusions, w_s is a total width of the steps in any cut surface; and z_s is an average depth of the steps.

Claims

1. An optical element comprising:

on a substrate, an anti-reflection layer on which a plurality of small concave protrusions, which have a modal pitch less than or equal to a wavelength of light in an environment where the optical element is to be used, are formed, wherein 80% or more of the concave protrusions have one step, and satisfy the following conditions;

0.09d≤

w_s≤

0.15d 

 

(5)

0.44h≤

z_s≤

0.56h 

 

(6)

wherein d is a maximum diameter of the concave protrusions observed in any cross-section including 30 to 40 or more concave protrusions, h is a difference in height between a deepest point and a highest portion of the concave protrusions observed in the cross-section including 30 to 40 or more concave protrusions, w_s is an average value of a total width of the step of each concave portion observed in the cross-section including 30 to 40 or more concave protrusions; and

z_s is an average depth of the step, wherein the modal pitch is a distance between adjacent concave protrusions obtained by a reciprocal of a distance from a zero-order peak to a first-order peak in a profile of a fast Fourier transform (FFT) image.

2. The optical element according to claim 1, wherein a modal depth which is an average depth of 30 to 40 or more concave protrusions in the cross-section including 30 to 40 or more concave protrusions is in a range of 45 to 55% of a median of a wavelength range of light in an environment in which the optical element is to be used.

3. The optical element according to claim 1, wherein an envelope of the concave protrusions including the step is conical.

4. The optical element according to claim 1, further comprising:

a plurality of areas continuously arranged in a positional relationship where a central point of seven of the concave protrusions that are adjacent is an intersection point of diagonal lines of six vertices of a regular hexagon,

wherein areas and shapes of the plurality of areas are random, and a six straight lines which are drawn connecting any concave protrusion in any area of the plurality of areas are at an angle of not less than 3 degrees with respect to a straight line which is drawn connecting central points of any two adjacent concave protrusions in an area adjacent to the area.

5. The optical element according to claim 1, wherein:

80% or more of the concave protrusions have one step, and satisfy the following conditions;

0.12d≤

ws≤

0.15d

0.44h≤

zs≤

0.52h.