# US 2025/0093649 A1 · Dual-Function Optic for Eye Display and Camera

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- Number: US 2025/0093649 A1
- Document ID: US20250093649A1
- Status: Published application
- Kind: A1
- Application number: 18/971,411
- Filed: 2024-12-06
- Published: 2025-03-20
- Earliest claimed: 2023-03-02
- Assignees: The Government of the United States, as represented by the Secretary of the Army
- Applicants: The Government of the United States, as represented by the Secretary of the Army
- Inventors: Bradley L. Preece; John M. Hall
- Web page: https://patentgrep.com/patent/US20250093649A1

## CPC

- G02B 27/0101: {characterised by optical features (G02B27/0172 takes precedence)}
- G02B 27/0172: {characterised by optical features}
- G02B 27/0179: {Display position adjusting means not related to the information to be displayed}
- G02B 27/1013: {for colour or multispectral image sensors, e.g. splitting an image into monochromatic image components on respective sensors (spectral imaging systems G01J)}
- G02B 27/30: Collimators
- G02B 2027/0138: {comprising image capture systems, e.g. camera}
- G02B 2027/014: {comprising information/image processing systems}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

For see-through AR displays, the current state of art uses geometric correction to lower the display location error, however this is far from an ideal solution and requires knowing range or pose of the devices. A dual-function optic for eye display & camera is disclosed, wherein a sensor camera imaging optics pipeline with a virtual projection point at an eye's retina reduces parallax errors to zero.

## Claims

### Claim 1

A dual-function optic of a bulk substrate material for near-to-eye display and camera, comprising:
an entrance surface of a bulk substrate material having a convex curvature coated with a hot mirror coating disposed as an upper surface to receive display light rays, wherein said hot mirror coating transmits a visible spectrum of said display light rays as a transmitted light beam, but reflects an infrared spectrum;
a 50% beamsplitter surface formed in the bulk substrate material at an angle of 45° to reflect roughly 50% of all wavelengths of light, including both visible and infrared, whereas light that is not reflected is transmitted as a further transmitted light;
a bottom curved surface of the bulk substrate material coated with a cold mirror coating disposed at an opposite end of the entrance surface to receive said further transmitted light of said transmitted light beam, wherein the cold mirror coating transmits an infrared spectrum but reflects the visible spectrum such that the bottom curved surface behaves as a concave mirror to reflect the visible spectrum of said further transmitted light with positive optical power, resulting in a reflected light, wherein the resulting reflected light incident back on the 50% beamsplitter surface is deflected at a 90° angle, resulting in a deflected light;
an exit portal surface of the bulk substrate material coated with the hot mirror coating to receive and transmit the deflected light as a visible light, wherein said exit portal surface is disposed for human eye viewing of the visible light; and
an exterior side surface of the bulk substrate material disposed at an opposite end of the exit portal surface of the bulk substrate material and coated with a broad-spectrum anti-reflection coating that transmits both visible and infrared spectra of a real world image incident on the exterior side surface such that the real world image that is transmitted is also viewable through the exit portal surface for human eye viewing, and such that of the real world image reflected by the 50% beamsplitter surface, an infrared spectrum of the real world image is reflected by the upper surface, partially transmitted back through the 50% beamsplitter surface, and transmitted through the bottom curved surface to be focused onto an infrared camera pixel array.

### Claim 2 (depends on 1)

The dual-function optic of a bulk substrate material recited in claim 1, wherein the 50% beamsplitter surface is formed in the bulk substrate material at an angle of 45° with respect to the transmitted light beam.

### Claim 3 (depends on 1)

The dual-function optic of a bulk substrate material recited in claim 1, wherein the bulk substrate material is based on either plastic or glass.

### Claim 4 (depends on 1)

The dual-function optic of a bulk substrate material recited in claim 1, wherein said hot mirror coating of said entrance surface is capable of transmitting a visible spectrum, generally with wavelengths between 0.45 and 0.75 microns, while reflecting an infrared spectrum, which includes wavelengths longer than 0.75 microns.

### Claim 5 (depends on 1)

The dual-function optic of a bulk substrate material recited in claim 1, wherein said convex curvature of said entrance surface induces positive optical power.

### Claim 6 (depends on 1)

The dual-function optic of a bulk substrate material recited in claim 1, wherein said 50% beamsplitter surface has a half-silvered coating cemented between two halves of the bulk substrate material to reflect roughly 50% of all wavelengths of light, including both visible and infrared, whereas light that is not reflected is transmitted.

### Claim 7 (depends on 1)

The dual-function optic of a bulk substrate material recited in claim 1, wherein the cold mirror coating reflects a visible spectrum within the range of 0.45 to 0.75 microns, and transmits infrared wavelengths greater than 0.75 microns.

### Claim 8 (depends on 1)

The dual-function optic of a bulk substrate material recited in claim 1, wherein a radius of curvature for the bottom curved surface collimates light.

### Claim 9 (depends on 1)

The dual-function optic of a bulk substrate material recited in claim 1, wherein the exterior side surface of the bulk substrate material coated with a broad-spectrum anti-reflection coating is disposed opposite to the exit portal surface to enable a simultaneous human eye viewing from the exit portal surface of the visible light as a display image and the real world image as an augmented reality, wherein said infrared camera pixel array facing the bottom curved surface is disposed to form an infrared image through an air gap.

### Claim 10

A dual-function optical system for eye display and camera, the dual-function optic system comprising:
a multi-pixel display screen disposed to emit visible spectrum light from a display screen surface as display light rays;
a dual-function optic of a plastic substrate material disposed for eye display and camera, the dual-function optic of the plastic substrate material comprising:
an entrance surface of the plastic substrate material having a convex curvature coated with a hot mirror coating disposed as an upper surface to face the display screen surface and receive the display light rays, wherein said hot mirror coating transmits a visible spectrum of said display light rays as a transmitted light beam, but reflects an infrared spectrum,
a 50% beamsplitter surface formed in the plastic substrate material at an angle of 45° with respect to the transmitted light beam from the entrance surface to reflect 50% of all wavelengths of the transmitted light beam from the entrance surface, whereas light that is not reflected by the 50% beamsplitter surface is transmitted through the 50% beamsplitter surface as a further transmitted light,
a bottom curved surface of the plastic substrate material coated with a cold mirror coating disposed at an opposite end of the entrance surface to receive said further transmitted light of said transmitted light beam, wherein the cold mirror coating transmits an infrared spectrum but reflects the visible spectrum such that the bottom curved surface behaves as a concave mirror to reflect the visible spectrum of said further transmitted light with positive optical power, resulting in a reflected light, wherein the resulting reflected light incident back on the 50% beamsplitter surface is deflected at a 90° angle, resulting in a deflected light,
an exit portal surface of the plastic substrate material coated with the hot mirror coating to receive and transmit the deflected light as a visible light, wherein said exit portal surface is disposed for human eye viewing of the visible light, and
an exterior side surface of the plastic substrate material disposed at an opposite end of the exit portal surface of the plastic substrate material and coated with a broad-spectrum anti-reflection coating that transmits both visible and infrared spectra of a real world image incident on the exterior side surface such that the real world image that is transmitted is also viewable through the exit portal surface for human eye viewing, and such that of the real world image reflected by the 50% beamsplitter surface, an infrared spectrum of the real world image is reflected by the upper surface, partially transmitted back through the 50% beamsplitter surface, and transmitted through the bottom curved surface;
an infrared camera receiver pixel array disposed to face the bottom curved surface of the plastic substrate material, capture the infrared spectrum of the real world scene image as transmitted through the bottom curved surface, and output an electrical video signal;
a digital signal processor to image process the electrical video signal to derive a mathematical matrix of pixel values representing a captured scene image; and
a control interface to the digital signal processor to allow user shifting of pixel positions of the captured scene image to result in a processed electronic image, whereby a processed electrical video signal representing the processed electronic image is sent to the multi-pixel display screen to emit said display light rays of the processed electronic image as a display image.

### Claim 11 (depends on 10)

The dual-function optical system recited in claim 10, wherein the control interface to the digital signal processor is used for manual alignment of the visible light of the display image over the real world image as seen directly through the exit portal surface, wherein the processed electrical video signal representing the processed electronic image is sent via a connection from the digital signal processor to the multi-pixel display screen to emit said display light rays of the processed electronic image as the display image.

### Claim 12 (depends on 10)

The dual-function optical system recited in claim 10, wherein a portion of the infrared spectrum light of the transmitted real world image impinging upon the 50% beamsplitter surface is reflected upward at a 90° angle toward a concave side of the upper surface, to be reflected by the hot mirror optical coating of the upper surface back to the 50% beamsplitter surface as a reflected infrared light beam, wherein a portion of the reflected infrared light beam passes through the 50% beamsplitter and continues down to the bottom curved surface to result in said infrared spectra of a real world scene image as transmitted through the bottom curved surface.

### Claim 13 (depends on 10)

The dual-function optical system recited in claim 10, wherein the infrared camera receiver pixel array is disposed with an air gap to face the bottom curved surface of the plastic substrate material to allow focusing of the infrared spectrum of the real world scene image, whereby the dual-function optic functions as an objective lens for said infrared camera receiver pixel array.

### Claim 14 (depends on 10)

The dual-function optical system recited in claim 10, wherein a connecting cable relays the electrical video signal to the digital signal processor to compute the mathematical matrix of pixel values.

### Claim 15 (depends on 10)

The dual-function optical system recited in claim 10, wherein the image processing includes image rotation, inversion, and distortion correction.

### Claim 16 (depends on 10)

The dual-function optical system recited in claim 10, wherein the control interface allows user shifting of pixel positions in vertical and horizontal directions for manual alignment of the visible light of the display image over the real world image as seen directly through the exit portal surface to achieve image overlap with no parallax.

### Claim 17 (depends on 10)

The dual-function optical system recited in claim 10, wherein the 50% beamsplitter surface reflects 50% of all wavelengths of the transmitted light beam from the entrance surface, including both visible and infrared, whereas light that is not reflected by the 50% beamsplitter surface is transmitted through the 50% beamsplitter surface at an angle of 45° to the 50% beamsplitter surface as a further transmitted light.