# US 2025/0147331 A1 · Prismatic collimating device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2025/0147331 A1 - Document ID: US20250147331A1 - Status: Published application - Kind: A1 - Application number: 18/684,343 - Filed: 2022-08-11 - Published: 2025-05-08 - Earliest claimed: 2021-08-16 - Assignees: BAE SYSTEMS plc - Applicants: BAE SYSTEMS plc - Inventors: Rory Thomas Alexander Mills - Web page: https://patentgrep.com/patent/US20250147331A1 ## CPC - G02B 19/0028: {refractive and reflective surfaces, e.g. non-imaging catadioptric systems} - G02B 27/30: Collimators - G02B 5/04: Prisms - G02B 19/0047: {for use with a light source (G02B19/009, G02B19/0095 take precedence; details of lighting devices in general F21V; non-semiconductor lasers having optical devices external to the laser cavity H01S3/005)} - G02B 27/0081: {with means for altering, e.g. enlarging, the entrance or exit pupil} - G02B 27/0172: {characterised by optical features} - G02B 2027/0174: {holographic} - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS ## Abstract A prismatic collimating device to collimate image bearing light is disclosed. The prismatic collimating device comprises a first prism and a second prism arranged to receive and collimate a light beam. The first prism comprises an output surface adjacent to an input surface of the second prism. The first prism and second prism are arranged such that the light beam undergoes total internal reflection and refraction at both the output surface of the first prism and the input surface of the second prism. Each of the first prism and second prism comprising at least three optically powered surfaces. ## Claims ### Claim 1 A prismatic collimating device to collimate image bearing light, the prismatic collimating device comprising: a first prism and a second prism; the first prism comprising a first surface, a second surface, and a third surface, the first surface configured to receive and refract image bearing light, from an image source, towards the second surface, the second surface configured to reflect light by total internal reflection, the light received from the first surface, towards the third surface, and refract light received, from the third surface, towards the second prism, and the third surface configured to reflect light received, from the second surface, towards the second surface; and the second prism comprising a fourth surface, a fifth surface, and a sixth surface, the fourth surface configured to receive and refract light, received from the third surface, towards the fifth surface, and reflect light by total internal reflection, the light received from the fifth surface, towards the sixth surface, the fifth surface configured to receive light, from the fourth surface, and reflect towards the fourth surface, and the sixth surface configured to receive and refract light, providing a collimated output, received from the fourth surface; wherein the first surface, second surface, third surface, fourth surface, fifth surface, and sixth surface are optically powered, and an air gap is provided between the second surface and the fourth surface. ### Claim 2 (depends on 1) The prismatic collimating device according to claim 1, wherein the first prism and the second prism have a substantially triangular cross-section. ### Claim 3 (depends on 1) The prismatic collimating device according to claim 1, further comprising a light source comprising a set of point sources. ### Claim 4 (depends on 1) The prismatic collimating device according to claim 1, wherein an exit pupil of collimated output comprises common coordinates in a horizontal axis and a vertical axis. ### Claim 5 (depends on 1) The prismatic collimating device according to claim 1, wherein an exit pupil of the prismatic collimating device has common coordinates in only one of a horizontal axis and a vertical axis. ### Claim 6 (depends on 1) The prismatic collimating device according to claim 1, wherein the air gap size is less than 1 mm. ### Claim 7 (depends on 1) The prismatic collimating device according to claim 1, wherein the second surface and the fourth surface have a substantially similar surface form. ### Claim 8 (depends on 1) The prismatic collimating device according to claim 1, wherein at least one of the first surface, second surface, and third surface have a substantially similar surface form to at least one of the fourth surface, fifth surface, and sixth surface. ### Claim 9 (depends on 1) The prismatic collimating device according to claim 1, wherein at least one of the first surface, second surface, fourth surface, and sixth surface is coated with an anti-reflection coating. ### Claim 10 (depends on 1) The prismatic collimating device according to claim 1, wherein the first prism and the second prism comprise one or more alignment features. ### Claim 11 (depends on 1) The prismatic collimating device according to claim 1, wherein at least one of the first surface, second surface, third surface, fourth surface, fifth surface, and sixth surface has a surface form substantially defined by at least one of: a spherical surface definition, an aspheric surface definition, a biconical surface definition, or a high order polynomial definition. ### Claim 12 (depends on 1) The prismatic collimating device according to claim 1, wherein the second surface is configured to reflect light received from a first range of angles, and transmit light received from a second range of angles, wherein the first range of angles and the second range of angles have substantially zero overlap. ### Claim 13 (depends on 1) The prismatic collimating device according to claim 1, wherein the fourth surface is configured to reflect light received from a third range of angles, and transmit light received from a fourth range of angles, wherein the third range of angles and the fourth range of angles have substantially zero overlap. ### Claim 14 A prismatic collimating device to collimate image bearing light, the prismatic collimating device comprising: a first prism and a second prism arranged to receive and collimate a light beam, wherein the first prism comprises an output surface adjacent to an input surface of the second prism, and the first prism and second prism are arranged such that the light beam undergoes total internal reflection and refraction at both the output surface of the first prism and the input surface of the second prism, and each of the first prism and second prism comprises at least three optically powered surfaces. ### Claim 15 (depends on 14) The prismatic collimating device according to claim 14, wherein: the first prism comprising a first surface, a second surface, and a third surface, the first surface configured to receive and refract image bearing light, from an image source, towards the second surface, the second surface is the output surface of the first prism and configured to reflect light by total internal reflection, the light received from the first surface, towards the third surface, and refract light received, from the third surface, towards the second prism, and the third surface configured to reflect light received, from the second surface, towards the second surface; and the second prism comprising a fourth surface, a fifth surface, and a sixth surface, the fourth surface is the input surface of the second prism and configured to receive and refract light, received from the third surface, towards the fifth surface, and reflect light by total internal reflection, the light received from the fifth surface, towards the sixth surface, the fifth surface configured to receive light, from the fourth surface, and reflect towards the fourth surface, and the sixth surface configured to receive and refract light, providing a collimated output, received from the fourth surface. ### Claim 16 (depends on 15) The prismatic collimating device according to claim 15, wherein the first prism and the second prism have a substantially triangular cross-section. ### Claim 17 A prismatic collimating device to collimate image bearing light, the prismatic collimating device comprising: a first prism and a second prism arranged to receive and collimate a light beam, wherein the first prism comprises an output surface adjacent to an input surface of the second prism, and an air gap is provided between the output surface and the input surface, and the first prism and second prism are arranged such that the light beam undergoes total internal reflection and refraction at both the output surface of the first prism and the input surface of the second prism, and each of the first prism and second prism comprises at least three optically powered surfaces. ### Claim 18 (depends on 17) The prismatic collimating device according to claim 17, wherein the first prism and the second prism have a substantially triangular cross-section, and the air gap size is less than 1 mm. ### Claim 19 (depends on 17) The prismatic collimating device according to claim 17, wherein: the output surface is configured to reflect light received from a first range of angles, and transmit light received from a second range of angles; and the input surface is configured to reflect light received from a third range of angles, and transmit light received from a fourth range of angles. ### Claim 20 (depends on 19) The prismatic collimating device according to claim 19, wherein the first range of angles and the second range of angles have zero overlap, and wherein the third range of angles and the fourth range of angles have zero overlap.