Concentric Afocal Beam Relay for Phase Preservation
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Solution Overview
Problem
Current pupil relay optics for 2-D beam scanning fail to meet requirements of low aberration, large deflection angles, phase preservation, large pupil size, afocality, color correction, low cost, and reduced size, with Offner-type optics being particularly inadequate as a beam relay due to phase wavefront preservation issues and higher order aberrations.
Innovation Solution
An afocal beam relay system incorporating a concave reflective surface, a convex reflective surface with coincident centers of curvature, and an aspheric corrector element positioned to relay a decentered entrance pupil to a decentered exit pupil, preserving the phase of the beam wavefront and correcting for aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If Offner-type optics are used for pupil relay in 2-D beam scanning, then the system can achieve compact size and large deflection angles, but the phase wavefront is not preserved and higher order aberrations occur
Solution Approach 1:
The patent divides the optical relay system into separate functional components: a first relay optic for primary beam relaying and a second relay optic for correcting aberrations and preserving phase. This segmentation allows each component to be optimized for its specific function, resolving the contradiction between compact size and phase preservation.
Solution Approach 2:
The second relay optic acts as an intermediary element that receives the beam from the first relay optic and corrects the wavefront phase. This intermediary component enables the system to maintain phase wavefront integrity while using compact Offner-type optics for the primary relaying function.
2Adaptability or versatility
If galvo mirrors are displaced from the entrance pupil to reduce NA requirements, then the numerical aperture of the scan lens can be reduced, but the beam deflection angle is limited and aperture size increases
Solution Approach 1:
The patent introduces a second relay optic that operates in a different optical dimension, correcting wavefront aberrations without requiring the mirrors to be positioned at the entrance pupil. This allows the system to achieve large deflection angles while maintaining a compact aperture size through wavefront phase correction in the image plane.
3Adaptability or versatility
If a pre-objective scanning system is used with two galvo mirrors, then 2-D scanning can be achieved, but the design becomes more complex and requires larger aperture lenses
Solution Approach 1:
The patent combines the functions of multiple optical elements into a streamlined system where the first relay optic performs primary beam relaying and the second relay optic handles aberration correction. This merging of functions reduces the overall system complexity compared to traditional pre-objective systems with multiple separate galvo mirrors and large aperture lenses.
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 effectively handles large deflection angles, maintains beam quality by preserving phase, and reduces the size and cost of components, while being color-corrected and diffraction-limited, making it suitable for laser scanning applications.
Implementation Method 1
a concave reflective surface having a first center of curvature and a first vertex that define an optical axis; a convex reflective surface having a second center of curvature that is substantially coincident with the first center of curvature
Implementation Method 2
an aspheric corrector element that is disposed in the path of input light that is directed to the decentered entrance pupil and that has correction values that are substantially centered on the first center of curvature
Data Source
AI summary
An afocal beam relay has a concave reflective surface having a first center of curvature and a first vertex that define an optical axis. A convex reflective surface has a second center of curvature that is substantially coincident with the first center of curvature and a second vertex that lies along the optical axis. The convex reflective surface faces toward the concave reflective surface to relay a decentered entrance pupil to a decentered exit pupil. An aspheric corrector element is disposed in the path of input light that is directed to the decentered entrance pupil and has correction values that are substantially centered on the first center of curvature.