Polygon Mirror Wheel Beam Shaping for Hologram Exposure
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Solution Overview
Problem
Existing beam shaping devices for hologram exposure machines, such as those using Powell lenses, suffer from manufacturing tolerances that lead to undesired stripe effects and intensity fluctuations, resulting in rejects during the exposure process.
Innovation Solution
A beam shaping device featuring a polygon wheel with a mirrored lateral surface and an electric drive unit, combined with a correction lens and a cylindrical lens, ensures a uniform intensity distribution by rotating the wheel at high speeds, independent of the laser beam profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a Powell lens is used for beam shaping, then the light beam can be expanded to form a scan line, but manufacturing tolerances cause stripe effects and intensity fluctuations
Solution Approach 1:
The patent replaces the static Powell lens (mechanical/optical component subject to manufacturing tolerances) with a dynamic polygon mirror wheel system. The polygon wheel with mirrored surfaces rotates to deflect the laser beam, creating the scan line without relying on precise lens grinding. This substitution eliminates stripe effects and intensity fluctuations caused by Powell lens manufacturing variations.
Solution Approach 2:
The invention introduces dynamic motion through the rotating polygon wheel to achieve beam shaping. Instead of using a static optical component (Powell lens), the system uses a moving polygon mirror that rotates at controlled speeds to scan the beam across the holographic film, creating a uniform intensity distribution through motion rather than static optical geometry.
2Shape
If a Powell lens is used for beam expansion, then a scan line can be formed, but the system becomes dependent on the laser beam profile
Solution Approach 1:
The patent replaces the Powell lens system that requires specific beam profile matching with a polygon mirror wheel system that is inherently more adaptable. The rotating polygon mirrors can deflect beams of various profiles without requiring precise profile matching, making the system versatile across different laser sources and beam conditions.
3Speed
If Powell lenses are used for beam shaping, then light can be expanded along a spatial direction, but tolerances in manufacture cause intensity fluctuations leading to rejects
Solution Approach 1:
The invention uses the dynamic rotation of the polygon wheel to achieve beam scanning and expansion. By controlling the rotation speed of the polygon wheel, the system can maintain consistent beam intensity across the scan line, eliminating the intensity fluctuations that cause rejects in Powell lens systems. The motion-based approach ensures reliable exposure quality.
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 provides a hologram exposure machine with improved hologram quality, reducing intensity fluctuations and rejects, as the beam shaping device ensures a homogeneous intensity distribution across the expanded light beam, regardless of manufacturing tolerances in the Powell lens.
Implementation Method 1
a wheel (352) which has a base area formed as a polygon, a cover area corresponding to the base area and a lateral surface (354) connecting the base area to the cover area and formed from mirrored rectangles
Implementation Method 2
an electric drive unit (356), which is designed to drive the wheel (352) in rotation about an axis of rotation oriented perpendicularly with respect to the direction of incidence of the light
Implementation Method 3
it has proven useful if a correction lens is introduced into the entrance opening
Implementation Method 4
A suitable widening, for example in only one spatial direction, can be brought about by a cylindrical lens, which is preferably plano-convex, also being arranged in the exit opening
Implementation Method 5
given sufficient rotation of the wheel, ensures a uniform intensity distribution of the light expanded by the beam-shaping device
Data Source
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AI summary
The invention relates to a beam shaping device (322) for a hologram exposure machine (300), comprising at least one inlet opening (350) for light (400) emitted by a light source (304), a wheel (352) having a base formed as a polygon, a top surface corresponding to the base, and a lateral surface (354) connecting the base and top surfaces and formed from mirrored rectangles, an electric drive unit (356) configured to rotate the wheel (352) about an axis of rotation oriented perpendicular to the direction of incidence of the light (400), and an outlet opening (358) for the light (400) reflected from the lateral surface (354). The invention also relates to a hologram exposure machine (300) with such a beam shaping device (322).