Spatial Light Modulator Optics for Compact Stable Laser Machining
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Solution Overview
Problem
Conventional laser machining devices have optical systems that are susceptible to angle errors and thermal expansion, leading to instability due to their large size, which increases the total length of the optical system.
Innovation Solution
The optical system is redesigned with a spatial light modulator and a second lens, where the distance from the second lens to the machining lens pupil is optimized to reduce the overall size, and the spatial light modulator is given a focal length that is -f2/M, allowing for a more compact and stable configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the focal length f2 of the second lens is increased to secure space for an auxiliary optical system, then the auxiliary optical system can be accommodated, but the distance L from the spatial light modulator to the machining lens pupil increases, resulting in a larger optical system size
Solution Approach 1:
The patent introduces a telecentric optical system that utilizes angular dimension control through specific lens arrangements (4F lens unit) to achieve both auxiliary optical system accommodation and compact overall size. The telecentric design allows light rays to be parallel to the optical axis at the pupil plane, enabling compact folding of the optical path while maintaining the required auxiliary system space.
2Adaptability or versatility
If the focal length f2 of the second lens is increased to accommodate the auxiliary optical system, then the auxiliary optical system can be provided, but the focal length f1 of the first lens must also be increased, leading to an increased distance L and larger optical system size
Solution Approach 1:
The patent designs the 4F lens unit (first lens L1 and second lens L2) to serve multiple functions simultaneously: it acts as a telecentric projection system for the spatial light modulator, provides the necessary auxiliary optical system space, and maintains a compact overall configuration. This multi-functional design eliminates the need for separate auxiliary optical systems while achieving the same goals.
3Adaptability or versatility
If the distance L from the spatial light modulator to the machining lens pupil is increased, then the auxiliary optical system can be accommodated, but the optical system becomes more susceptible to angle errors and thermal expansion, reducing machining stability
Solution Approach 1:
The patent replaces traditional mechanical optical path arrangements with a telecentric optical system that uses optical principles (parallel light rays at pupil plane) to achieve the same auxiliary system integration goals. This substitution reduces sensitivity to mechanical angle errors and thermal expansion by making the optical path less dependent on precise mechanical alignment over long distances.
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 configuration reduces the distance from the spatial light modulator to the machining lens pupil, enhancing the stability of laser machining and allowing for a more compact optical system.
Implementation Method 1
a spatial light modulator that modulates laser light LB to be used for machining on a workpiece W
Implementation Method 2
an optical system that relays the laser light LB modulated by the spatial light modulator 24 to a machining lens 26
Data Source
AI summary
An optical system that relays light to a machining lens to be used for machining on a workpiece includes a spatial light modulator and a second lens arranged between the spatial light modulator and the machining lens, a distance D from the second lens to a machining lens pupil is D = f2 - Mf2, and a distance D1 from the spatial light modulator to the second lens is D1 = f2 - f2/M, and the spatial light modulator has a conjugate relation with the machining lens pupil of the machining lens, where f2 is a focal length of the second lens, and M is a projection magnification from the spatial light modulator to the machining lens pupil of the machining lens.