# US 2025/0085459 A1 · Hardened optical windows with anti-reflective films having low visible reflectance and transmission for infrared sensing systems

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- Number: US 2025/0085459 A1
- Document ID: US20250085459A1
- Status: Published application
- Kind: A1
- Application number: 18/701,451
- Filed: 2022-10-07
- Published: 2025-03-13
- Earliest claimed: 2021-10-20
- Assignees: Corning Incorporated
- Applicants: Corning Incorporated
- Inventors: Shandon Dee Hart; Karl William Koch, III; Carlo Anthony Kosik Williams; Lin Lin; Rui Luo; James Joseph Price; Nicholas Michael Walker
- Web page: https://patentgrep.com/patent/US20250085459A1

## CPC

- G02B 1/115: Multilayers
- G02B 1/14: Protective coatings, e.g. hard coatings
- G02B 5/281: {designed for the infrared light}
- G01S 7/4813: {Housing arrangements}
- G01S 17/931: of land vehicles
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES

## Abstract

Disclosed is a window for a sensing system comprising a substrate, a first layered film comprising alternating layers of higher and lower index materials, and a second layered film comprising alternating layers of higher and lower index materials. The window comprises a maximum hardness, measured at the first layered film and by the Berkovich Indenter Hardness Test, of at least 8 GPa. The first and second layered films are configured so that the window has favorable antireflective and transmission attributes in an infrared wavelength range of interest, while providing relatively low reflectance and transmittance in the visible spectrum to provide a dark appearance and low signal noise.

## Claims

### Claim 1

A window for a sensing system comprising:
a substrate comprising a first surface and a second surface, the first surface and the second surface being primary surfaces of the substrate;
a first layered film disposed on the first surface of the substrate, the first layered film comprising alternating layers of one or more higher refractive index materials and one or more lower refractive index materials, wherein refractive indices of the one or more higher refractive index materials of the first layered film are higher than refractive indices of the one or more lower refractive index materials of the first layered film;
a second layered film disposed on the second surface of the substrate, the second layered film comprising alternating layers of one or more higher refractive index materials and one or more lower refractive index materials, wherein refractive indices of the one or more higher refractive index materials of the second layered film are higher than refractive indices of the one or more lower refractive index materials of the second layered film; and
a maximum hardness, measured at the first layered film and by the Berkovich Indenter Hardness Test, of at least 8 GPa,
wherein the quantity, the thicknesses, number, and materials of the alternating layers of the first and second layered films are configured so that the window has:
an average percentage transmittance, calculated over a 50 nm wavelength range of interest between 1400 nm and 1600 nm, of greater than 90% for light incident on the first surface and the second surface at angles of incidence of less than or equal to 15°;
an average reflectance, calculated over the 50 nm wavelength range of interest between 1400 nm and 1600 nm, of less than 1% for light incident on the first surface and the second surface at angles of less than or equal to 15°; and
an average percentage transmission, calculated from 400 nm to 700 nm, of less than 5% for light incident on the first surface and the second surface at angles of incidence of less than or equal to 15°.

### Claim 2 (depends on 1)

The window of claim 1, wherein the quantity, the thicknesses, number, and materials of the alternating layers of the first and second layered films are configured so that the window has an average P polarization transmittance and an average S polarization transmittance, calculated over the 50 nm wavelength range of interest between 1400 nm and 1600 nm, of greater than 85% for light incident on the first surface and the second surface at angles of incidence of less than or equal to 60°.

### Claim 3

(canceled)

### Claim 4 (depends on 1)

The window of claim 1, wherein the quantity, the thicknesses, number, and materials of the alternating layers of the first and second layered films are configured so that the window has a CIELAB L* value of less than or equal to 45 for angles of incidence of less than or equal to 60° on the first layered film.

### Claim 5

(canceled)

### Claim 6 (depends on 1)

The window of claim 1, wherein the quantity, the thicknesses, number, and materials of the alternating layers of the first and second layered films are configured so that the window has CIELAB a* and b* values of greater than or equal to −6.0 and less than or equal to 6.0 when viewed from a side of the first layered film.

### Claim 7 (depends on 1)

The window of claim 1, wherein the quantity, the thicknesses, number, and materials of the alternating layers of the first and second layered films are configured so that the window has an average reflectance, calculated throughout the visible spectrum, for light normally incident on the first layered film, of less than or equal to 10%.

### Claim 8

(canceled)

### Claim 9

(canceled)

### Claim 10

(canceled)

### Claim 11

(canceled)

### Claim 12

(canceled)

### Claim 13 (depends on 1)

The window of claim 1, wherein the refractive index of the one or more higher refractive index materials is from about 1.7 to about 4.0, and wherein the refractive index of the one or more lower refractive index materials is from about 1.3 to about 1.6, wherein a difference in the refractive index of any of the one or more higher refractive index materials and any of the one or more lower refractive index materials is about 0.5 or greater.

### Claim 14

(canceled)

### Claim 15 (depends on 1)

The window of claim 1, wherein one of the alternating layers of the first layered film that is farthest from the substrate forms a terminal surface material of the window, the terminal surface material of the window comprising the lower refractive index material.

### Claim 16 (depends on 15)

The window of claim 15, wherein first layered firm comprises a scratch resistant layer formed of one of the one or more higher refractive index materials and having a thickness of greater than or equal to 500 nm.

### Claim 17 (depends on 16)

The window of claim 16, wherein the thickness of the scratch resistant layer is greater than or equal to 1500 nm and less than or equal to 5000 nm.

### Claim 18 (depends on 17)

The window of claim 17, wherein the scratch resistant layer is separated from the terminal surface by a plurality of the alternating layers of the one or more lower index materials and the one or more higher index materials of the first layered film.

### Claim 19 (depends on 18)

The window of claim 18, wherein the scratch resistant layer is separated from the terminal surface by at least 1000 nm.

### Claim 20 (depends on 1)

The window of claim 1, wherein the one or more higher refractive index materials of the second layered film comprise silicon, wherein the second layered film comprises two or more silicon layers.

### Claim 21

(canceled)

### Claim 22 (depends on 20)

The window of claim 20, wherein a silicon layer of the second layered film most proximate to the substrate comprises the smallest thickness of the two or more silicon layers.

### Claim 23 (depends on 20)

The window of claim 20, wherein a combined thickness of the silicon layers contained in the second layered film is greater than or equal to 250 nm.

### Claim 24

(canceled)

### Claim 25 (depends on 20)

The window of claim 20, wherein a layer of the one or more higher refractive index materials in the second layered film is not silicon.

### Claim 26

(canceled)

### Claim 27

(canceled)

### Claim 28 (depends on 1)

The window of claim 1, wherein a hardness, measured at the first layered film and by the Berkovich Indenter Hardness Test, is at least 9 GPa over a depth range of 750 nm to 2000 nm.

### Claim 29

A window for a sensing system comprising:
a substrate comprising a first surface and a second surface, the first surface and the second surface being primary surfaces of the substrate;
a first layered film disposed on the first surface of the substrate, the first layered film comprising alternating layers of one or more higher refractive index materials and one or more lower refractive index materials, wherein refractive indices of the one or more higher refractive index materials of the first layered film are higher than refractive indices of the one or more lower refractive index materials of the first layered film;
a second layered film disposed on the second surface of the substrate, the second layered film comprising alternating layers of one or more higher refractive index materials and one or more lower refractive index materials, wherein refractive indices of the one or more higher refractive index materials of the second layered film are higher than refractive indices of the one or more lower refractive index materials of the second layered film; and
a maximum hardness, measured at the first layered film and by the Berkovich Indenter Hardness Test, of at least 8 GPa,
wherein the quantity, the thicknesses, number, and materials of the alternating layers of the first and second layered films are configured so that the window has:
an average reflectance, calculated over a 50 nm wavelength range of interest between 1400 nm and 1600 nm, of less than 0.5% for light incident on the first surface and the second surface at angles of less than or equal to 15°;
a CIELAB L* value of less than or equal to 45 for angles of incidence of less than or equal to 600 on the first layered film; and
CIELAB a* and b* values of greater than or equal to −6.0 and less than or equal to 6.0 when viewed from a side of the first layered film.

### Claim 30 (depends on 29)

The window of claim 29, wherein the CIELAB L* value is less than or equal to 30 for angles of incidence of less than or equal to 600 on the first layered film.

### Claim 31 (depends on 29)

The window of claim 29, wherein the quantity, the thicknesses, number, and materials of the alternating layers of the first and second layered films are configured so that the window has an average percentage transmittance, calculated over the 50 nm wavelength range of interest between 1400 nm and 1600 nm, of greater than 95% for light incident on the first surface and the second surface at angles of incidence of less than or equal to 15°.

### Claim 32 (depends on 31)

The window of claim 31, wherein the quantity, the thicknesses, number, and materials of the alternating layers of the first and second layered films are configured so that the window has an average percentage transmission, calculated from 400 nm to 700 nm, of less an 5% for light incident on the first surface and the second surface at angles of incidence of less than or equal to 15°, wherein the quantity, the thicknesses, number, and materials of the alternating layers of the first and second layered films are configured so that the window has an average reflectance, calculated throughout the visible spectrum, for light normally incident on the first layered film, of less than or equal to 10%.

### Claim 33

(canceled)

### Claim 34

(canceled)

### Claim 35

(canceled)

### Claim 36

(canceled)

### Claim 37

(canceled)

### Claim 38

(canceled)

### Claim 39

(canceled)

### Claim 40

(canceled)

### Claim 41

(canceled)

### Claim 42

(canceled)

### Claim 43

(canceled)

### Claim 44

(canceled)

### Claim 45

(canceled)

### Claim 46

(canceled)

### Claim 47

(canceled)

### Claim 48

(canceled)

### Claim 49

(canceled)

### Claim 50

(canceled)

### Claim 51

(canceled)

### Claim 52

(canceled)

### Claim 53

(canceled)

### Claim 54

(canceled)

### Claim 55

(canceled)

### Claim 56

(canceled)

### Claim 57

(canceled)

### Claim 58

(canceled)

### Claim 59

(canceled)

### Claim 60

(canceled)

### Claim 61

(canceled)

### Claim 62

(canceled)