Off-Axis Aspheric Mirrors for Telecentric Laser Scanning
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Solution Overview
Problem
Current optical scanner systems for laser material processing face challenges in maintaining a constant spot size and energy density across the scanned path, with existing telecentric f-theta objectives being costly and limited in scan width, and prior art designs suffering from significant line bow and aberrations, which affect the precision and accuracy of the scanning process.
Innovation Solution
A scanning system utilizing off-axis, rotationally symmetric aspheric mirrors with decentered apertures, optimized for telecentricity and minimal line bow, comprising a combination of aspheric and spherical mirrors to achieve diffraction-limited performance and maintain a constant spot size across the scanned surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a telecentric f-theta objective is used to maintain constant spot size and energy density, then the scanning performance is improved, but the device complexity and cost increase significantly
Solution Approach 1:
The optical system is divided into separate functional modules: a telecentric scanning element for maintaining constant spot size and an f-theta objective for focusing and linear scanning. This segmentation allows each component to be optimized independently, reducing overall system complexity while maintaining high scanning precision.
Solution Approach 2:
A telecentric scanning element is introduced as an intermediary component between the light source and the f-theta objective. This intermediary maintains the beam diameter constant across the scan field, enabling the use of simpler, less expensive optical elements while achieving telecentric performance without requiring complex multi-element designs.
2Area of stationary object
If a telecentric f-theta objective with larger diameter is used to extend scanned path length, then the scanning area is improved, but the device complexity and cost increase
Solution Approach 1:
The system uses a rotating or oscillating scanning element that dynamically deflects the beam across the scan field. This dynamic scanning approach allows the use of compact optical elements with smaller diameters while achieving extended scanned path lengths through angular deflection, eliminating the need for large-diameter static optical components.
Solution Approach 2:
The system transitions from a static optical path to a dynamic angular scanning approach. By using rotational or oscillational motion of the scanning element, the beam is deflected across a large area without requiring large-diameter optical elements, effectively using the angular dimension to achieve extended scanning coverage.
3Device complexity
If compact f-theta lenses are used to reduce device size, then the device complexity is reduced, but the scanning precision and energy density consistency deteriorate
Solution Approach 1:
The optical system is divided into separate functional modules: a telecentric scanning element for maintaining constant spot size and an f-theta objective for focusing and linear scanning. This segmentation allows each component to be optimized independently, reducing overall system complexity while maintaining high scanning precision.
Solution Approach 2:
A telecentric scanning element is introduced as an intermediary component between the light source and the f-theta objective. This intermediary maintains the beam diameter constant across the scan field, enabling the use of simpler, less expensive optical elements while achieving telecentric performance without requiring complex multi-element designs.
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
The solution provides a cost-effective, high-performance telecentric scanner with reduced line bow and spot size variation, ensuring consistent energy density and precision across the scanned path, enhancing the accuracy and efficiency of laser material processing.
Implementation Method 1
an optical system between the scanning element and the second port, wherein the optical system comprises at least a first mirror and a second mirror having a rotationally symmetric curved mirror surface about their optical axis
Implementation Method 2
achieve diffraction-limited performance and maintain a constant spot size across the scanned surface
Data Source
AI summary
The present invention provides a scanning system (100) comprising a first port for receiving or emitting a stationary beam (60) of electromagnetic radiation, a second port for emitting or receiving a scanning beam of electromagnetic radiation, the scanning beam scanning in a main scanning direction, a scanning element (61) for relaying the stationary beam (60) into the scanning beam or vice versa, an optical system between the scanning element (61) and the second port, wherein the optical system comprises at least a first mirror (63) and a second mirror (64) having a rotationally symmetric curved mirror surface around their optical axis, at least one of the first and the second curved mirror surface having an aspheric shape, and wherein the first and the second mirror (63, 64) have an off-axis decentered aperture and are offset in position in a direction perpendicular to the main scanning direction.