Method of measuring efficiency for optical devices
Inventors
FU, Jinxin • Sun, Yangyang • DAITO, Kazuya • Godet, Ludovic
Assignees
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Publication Number
US-12379280-B2
Publication Date
2025-08-05
Expiration Date
Abstract
Embodiments of the present disclosure relate to measurement systems and methods of measuring efficiency of optical devices. In one example, the measurement systems include a light source, a mirror, an illumination source, and a sensor. The light source provides a light beam to the optical device to be diffracted into diffraction beams having diffraction orders. The diffractions beams form a diffraction pattern. The method includes positioning the optical device in the measurement system and directing the diffraction beams to the sensor. The sensor is operable to measure the efficiency of the optical device by measuring the diffraction pattern.
Core Innovation
The invention provides a measurement system for measuring diffraction efficiency of an optical device. A light source projects a light beam to an objective lens, where the light beam includes diffraction beams produced by the optical device, and the diffraction beams form a diffraction pattern that includes diffraction orders and corresponding light spots.
The measurement system directs the diffraction beams from the objective lens toward a sensor by using a first mirror and two or more relay lenses. The first mirror reflects the diffraction beams through the two or more relay lenses, and the relay lenses position the diffraction beams so the diffraction pattern is directed to the sensor.
An illumination source is disposed opposite the light source to project white light toward a second mirror, and the second mirror reflects the white light toward the objective lens. The disclosed approach enables parallel measurement of multiple diffraction orders by imaging or relaying the diffraction pattern to a sensor and measuring intensity of a plurality of light spots.
Claims Coverage
The independent claim defines an optical measurement system with a light source, an objective lens producing diffraction beams, a first mirror and two or more relay lenses directing a diffraction pattern to a sensor, and a separate white-light illumination path using a second mirror for illumination toward the objective lens. Four inventive features are identified in the independent claim, with dependent claims refining the optical path and sensing arrangement.
White-light illumination path for objective lens alignment
An illumination source disposed opposite the light source, the illumination source configured to project white light toward a second mirror, the second mirror positioned to reflect the white light toward the objective lens.
Diffraction pattern imaging using a first mirror and relay lenses
A first mirror operable to reflect the diffraction beams from the objective lens through two or more relay lenses, wherein the two or more relay lenses are positioned to direct the diffraction beams having a diffraction pattern to the sensor.
Objective lens producing diffraction beams from optical device illumination
An objective lens disposed in the light beam, the light beam including diffraction beams.
Parallel diffraction-order intensity sensing via a sensor
The diffraction beams produce a plurality of light spots in a diffraction pattern, and the sensor measures the intensity of each light spot.
Real image formation using a tube lens
The measurement system further includes a tube lens that directs the diffraction beams to form a real image.
Dichroic first mirror for reflecting diffraction beams
The first mirror is a dichroic mirror.
Two-dimensional LIDAR sensor for diffraction pattern sensing
The sensor is a 2D LIDAR sensor.
High numerical aperture objective lens range
The objective lens has a numerical aperture (NA) between about 0.5 and about 1.0.
Overall claim coverage centers on imaging a diffraction pattern from an objective lens onto a sensor using a first mirror and two or more relay lenses, while providing a separate white-light illumination path toward the objective lens. Dependent claims further refine real-image formation with a tube lens, specify a dichroic first mirror, constrain the sensor to a 2D LIDAR sensor, set an objective NA range, and define measuring the intensity of multiple light spots in the diffraction pattern.
Stated Advantages
Allows determining diffraction efficiency and uniformity from measured intensity of light spots corresponding to diffraction orders.
Enables parallel measurement of multiple diffraction orders by directing a diffraction pattern to a sensor with a large-area sensor and high numerical aperture.
Documented Applications
Measuring diffraction efficiency of optical devices, including determining efficiency and uniformity during production lines.
Measuring diffraction-pattern light-spot intensities across a plurality of diffraction orders using sensor imaging of the diffraction pattern.
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