Conical Scan Generator for High-Speed Optical Imaging
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Solution Overview
Problem
Conventional optical scanning systems are limited by the rate at which a focused beam moves across an area of interest, restricting the scan frequency and efficiency of object scanning.
Innovation Solution
The method involves scanning an incident beam in a substantially closed plane curve, such as a circular pattern, with the object moved orthogonally to the scan plane, using a conical scan generator with a rotating wedged mirror or holographic transmission grating, allowing for higher scan frequencies and simpler optical systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional optical scanning systems use a focused beam moving across an area of interest, then image scanning is achieved, but the scan frequency is limited by the beam movement rate
Solution Approach 1:
The patent transitions from linear beam movement in one dimension to conical scanning in three dimensions. The beam is scanned in a conical pattern around the objective lens, creating a circular scan pattern at the object plane. This dimensional change allows the beam to cover the same area more rapidly by utilizing rotational motion around the optical axis, thereby increasing scan frequency without being constrained by linear beam movement speed.
Solution Approach 2:
The invention employs dynamic scanning where the beam position is continuously changed in a conical pattern rather than moving linearly. The conical deflector (rotating wedge or holographic grating) creates a dynamically scanning beam that rotates around the objective lens, enabling faster scanning by utilizing the rotational dynamics of the conical pattern rather than sequential linear beam movement.
2Productivity
If conventional optical scanning systems increase scan frequency, then scanning efficiency improves, but system complexity increases
Solution Approach 1:
The patent replaces complex mechanical beam steering mechanisms with a conical deflector that uses optical elements (rotating wedge or holographic transmission grating) to achieve beam scanning. This substitution of mechanical beam movement with optical conical scanning simplifies the overall system while enabling high scan frequencies, as the optical elements can rotate or modulate much faster than mechanical beam positioning systems.
Solution Approach 2:
By introducing conical scanning in three-dimensional space around the objective lens, the system achieves efficient area coverage without requiring complex multi-axis mechanical scanners. The conical pattern naturally distributes the beam across the field of view, simplifying the scanning mechanism while maintaining high scanning efficiency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach increases scan frequency, simplifies the optical system design, and enhances scanning efficiency by limiting the scan frequency only by the rotation speed of the scanning elements, achieving high-speed scanning with commercial air-bearing-mounted rotating mirrors.
Implementation Method 1
reflecting a confocal beam off a first steering mirror as a reflected confocal beam; reflecting the reflected confocal beam off a rotating wedge mirror and providing an exit beam that forms a cone of angles
Implementation Method 2
a spinning refractive wedge or holographic transmission grating. The refractive wedge or transmission grating may be mounted on an air bearing and spun at high frequency
Implementation Method 3
a spinning refractive wedge or holographic transmission grating
Implementation Method 4
The refractive wedge or transmission grating may be mounted on an air bearing and spun at high frequency
Data Source
AI summary
A method and apparatus is provided for scanning an object, featuring scanning an incident beam in a substantially curved scan pattern; and moving an object at a predetermined rate along an axis substantially orthogonal to a plane of the curved scan pattern so that a two dimensional image can be formed by successive passes of a circularly scanned spot. In particular, a laser beam scans around an objective lens at a fixed radius RL with a fixed input angle θd. When scanned in this manner, the laser beam before the objective lens forms a “cone” of directions (so herein it is referred to as a “conical scan”). Scanning in this fashion produces the curved scan pattern at the object (substrate). By moving the object (substrate) at the predetermined rate along the axis orthogonal to the plane of the curved scan pattern, the two dimensional image can be formed by successive passes of the circularly scanned spot.