Resin Collimator Lens Gate Positioning for Birefringence Control
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Solution Overview
Problem
Resin collimator lenses in optical scanning apparatuses suffer from birefringence-induced optical characteristic variations, leading to image deterioration due to uneven influence on laser beams from multiple light emitting points, and existing solutions increase lens volume and material cost by forming gate portions at the edge.
Innovation Solution
A collimator lens with a gate portion positioned at the outer circumference, held by a cylindrical holder such that the line connecting the gate and lens center is parallel or orthogonal to the beam paths, minimizing birefringence impact on laser beams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the gate portion is formed at the edge portion extending from the side surface of the collimator lens to prevent birefringence influence, then image quality is improved, but the lens diameter and material cost increase
Solution Approach 1:
The patent positions the gate portion at a specific asymmetric location on the lens periphery rather than forming it symmetrically at all edges. By strategically placing the gate at one specific edge portion and controlling its extension direction, the design prevents birefringence from affecting the beam transmitting region while avoiding the need to increase the overall lens diameter uniformly in all directions.
Solution Approach 2:
The patent applies local quality control by forming the gate portion only at specific critical edge regions where birefringence would otherwise affect the optical path, rather than uniformly treating the entire lens periphery. This localized approach prevents harmful birefringence effects in the beam transmitting region while minimizing the overall lens volume increase.
2Stability of the object's composition
If the gate portion is formed at the edge portion to prevent birefringence, then optical characteristic uniformity is improved, but the lens volume increases
Solution Approach 1:
The patent employs asymmetric positioning of the gate portion at a specific edge location rather than symmetric distribution around the lens. This asymmetric placement ensures that the gate effectively blocks birefringence effects from reaching the beam transmitting region while minimizing the additional volume required compared to symmetric edge treatments.
Solution Approach 2:
The gate portion is localized to specific edge regions where birefringence would impact optical uniformity, rather than being distributed throughout the entire lens structure. This localized approach maintains optical characteristic uniformity in the critical beam transmitting areas while keeping the overall lens volume increase to a minimum.
3Ease of manufacture
If the collimator lens is made of resin to reduce cost, then manufacturing cost is reduced, but birefringence causes optical characteristic variation
Solution Approach 1:
The patent converts the harmful effect of birefringence in resin lenses into a manageable issue by strategically positioning the gate portion. Instead of trying to eliminate birefringence entirely (which would require expensive glass materials), the design uses the gate to control and direct the birefringence effects away from the beam transmitting region, thereby maintaining both low cost and optical uniformity.
Solution Approach 2:
The gate portion acts as an intermediary element between the resin material (with its inherent birefringence) and the laser beams. By positioning the gate at the edge portion, it mediates the interaction between the birefringent resin and the optical paths, preventing direct harmful interaction while allowing the low-cost resin material to be used.
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 increase in spot diameter and maintains high image quality at a lower cost by minimizing birefringence influence on laser beams, achieving uniform optical performance across multiple light emitting points.
Implementation Method 1
The collimator lens converts laser light emitted from the light source unit into parallel beams
Implementation Method 2
birefringence distributed depending on a direction in which the resin is poured into the mold, that is, a direction of a gate portion extending from a lens outer circumferential portion is caused in the collimator lens made of a resin
Data Source
AI summary
A collimator lens is held by a holder so that, while viewing the collimator lens in an axial direction of a plurality of beams passing through the collimator lens, a straight line connecting between a center of the collimator lens and a gate portion is substantially parallel or substantially orthogonal to a straight line connecting between centers of the plurality of beams transmitting through the collimator lens.