Antireflective stack for low luminance conditions

• US 10,605,959 B2
• Filed: 12/30/2015
• Issued: 03/31/2020
• Est. Priority Date: 12/31/2014
• Status: Active Grant

• Current Assignee: Essilor International SA
• Original Assignee: Essilor International SA
• Inventors: Liu, Yu, Ding, Xingzhao
• Primary Examiner(s): Collins, Darryl J
• Assistant Examiner(s): Sumlar, Journey F
• Application Number:
  US15/540,224
• Publication Number:
  US 20190056530A1
• Time in Patent Office: 1,553 Days
• Field of Search: None
• CPC Class Codes: C03C 17/3417 all coatings being oxide coatings
• CPC Class Codes: C03C 2217/734 comprising an alternation of high and low refractive indexes
• CPC Class Codes: C03C 2218/151 by vacuum evaporation
• CPC Class Codes: G02B 1/115 Multilayers
• CPC Class Codes: G02B 27/0012 Optical design, e.g. procedures, algorithms, optimisation routines
• CPC Class Codes: G02C 7/02 Lenses; Lens systems ; Methods of designing lenses

Abstract

Ophthalmic lens comprising an anti-reflective stack designed for scotopic or mesopic conditions, wherein the anti-reflective stack design method uses the scotopic luminosity function CIE 1951 (defined by the Commission Internationale de I'"'"'Eclairage).

Claims

1. An ophthalmic lens comprising an anti-reflective stack designed for scotopic or mesopic conditions, wherein:

the anti-reflective stack design method uses the spectral luminous efficiency function V′

(λ

) as defined in CIE 1951 and an average spectral luminous efficiency function V<sub>α

,β</sub>

(λ

)=α

V(λ

)+β

V′

(λ

), with β

>

0, V(λ

) is in CIE 1931 and V′

(λ

) is in CIE 1951; and

the anti-reflective stack has a mean light reflection R_V<sup>α

,β</sup>

value that is calculated according to;

2. The ophthalmic lens according to claim 1 comprising a transparent substrate with a front main face and with a rear main face, at least one of the main faces being coated with a multilayered anti-reflective stack comprising at least one layer having a refractive index higher than or equal to 1.55 and at least one layer having a refractive index lower than 1.55, such that:

the mean light reflection factor in the visible region for photopic vision R_V with D₆₅ illuminant is lower than or equal to 0.5%, for at least an angle of incidence lower than 35°

; and

the mean light reflection factor in the visible region for scotopic or mesopic vision R_V<sup>α

,β</sup>

with D₆₅ illuminant is lower than the mean light reflection factor in the visible region for photopic vision R_V for at least an angle of incidence lower than 35° and

a ratio α

/β

≤

10.

3. The ophthalmic lens according to claim 2, wherein the multilayered anti-reflective coating comprises a number of layers higher than or equal to 3 and lower than or equal to 10, preferably higher than or equal to 4 and lower than or equal to 6.

4. The ophthalmic lens according to claim 1, wherein the hue of the light reflected by the anti-reflective coating is in the range from 0°

to 150°

for at least an angle of incidence lower than 35°

.

5. The ophthalmic lens according to claim 1, wherein mean reflection factor Rm of anti-reflective coating is lower than 1% for at least an angle of incidence lower than 35°

.

6. The ophthalmic lens according to claim 1, wherein the anti-reflective coating comprises, in the direction moving away from the substrate, a layer having a refractive index higher than or equal to 1.55 with a thickness of from 10 to 25 nm, a layer having a refractive index lower than 1.55 with a thickness of from 20 to 35 nm, a layer having a refractive index higher than 1.55 with a thickness of from 60 to 110 nm, optionally an electrically conductive layer with a thickness of from 3 to 10 nm, and a layer having a refractive index lower than 1.55, with a thickness of from 70 to 95 nm.

7. The ophthalmic lens according to claim 1 comprising a front face coated with said multilayered anti-reflective stack and an indication of a visual rating associated with the ophthalmic lens, wherein the visual rating including a ratio based on values α

and β

defining the average spectral luminous efficiency function V<sub>α

,β</sub>

(λ

) used for designing the anti-reflective stack.

8. A method of designing an anti-reflective stack comprising:

(a) identifying a luminance in the scotopic vision regime;

(b) calculating the weighted mean light reflection in scotopic conditions R_V′

of an anti-reflective stack having a light reflection spectrum R(λ

) according to;

9. The method of claim 8, wherein R_V′

is less than or equal to 1%, preferably less than or equal to 0.5%.

10. The method of claim 8, further defined as manufacturing an ophthalmic lens having an anti-reflective stack, further comprising:

(d) providing an optical article having two main faces; and

(e) forming the anti-reflective stack on at least one main face of the ophthalmic lens.

11. A method of designing an anti-reflective stack comprising:

(a) identifying a range of luminance in the scotopic and/or mesopic vision regime;

(b) calculating the average spectral luminous efficiency function V<sub>α

,β</sub>

(λ

) of the range of luminance according to;

V<sub>α

,β</sub>

(λ

)=α

V(λ

)+β

V′

(λ

)

wherein α and

β

are selected according to the luminance conditions, β

>

0, V(λ

) is in CIE 1931 and V′

(λ

) is in CIE 1951;

(c) designing an anti-reflective stack by use of V<sub>α

,β</sub>

(λ

) function.

12. The method of designing an anti-reflective stack according to claim 11 in which step (c) comprises the following steps:

(c1) calculating the weighted mean light reflection R_V<sup>α

,β</sup>

of an anti-reflective stack having a light reflection spectrum R(λ

) according to;

13. The method of claim 11, wherein R_V^α

,β

is less than or equal to 1%, preferably less than or equal to 0.5%.

14. The method of claim 11, further defined as manufacturing an ophthalmic lens having an anti-reflective stack, further comprising:

(d) providing an optical article having two main faces; and

(e) forming the anti-reflective stack on at least one main face of the ophthalmic lens.

15. The method of claim 14 further comprising providing to a customer of said ophthalmic lens a rating of the ophthalmic lens with respect to luminance conditions, the rating being based on a ratio α

/β

, which quantifies the anti-reflective efficiency of the ophthalmic lens in scotopic or mesopic conditions.