Bi-acylindrical Lens for Laser Diode Beam Collimation
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Solution Overview
Problem
Laser diodes emit astigmatic light, resulting in elliptical beams that are not easily collimated into circular beams, which is undesirable for applications requiring a round collimated beam.
Innovation Solution
A bi-acylindrical lens system is used, comprising two acylindrical lenses oriented at 90 degrees to each other's axes, matching focal lengths to the divergence ratio of the laser diode, to collimate the light beam on both the fast and slow axes, producing a round collimated beam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an aspherical collimating lens is placed in front of a laser diode, then the beam is collimated in one direction, but the beam focuses at different locations in the X and Y directions resulting in an elliptical beam
Solution Approach 1:
The patent divides the collimation function into two separate acylindrical lenses, each responsible for collimating light in one specific direction (fast axis or slow axis). This segmentation allows independent optimization of collimation for each axis, transforming the elliptical beam into a circular beam while maintaining collimation.
2Ease of operation
If a single aspherical lens is used to collimate laser diode light, then collimation is achieved, but the astigmatic nature of the laser diode causes different focal points in different directions
Solution Approach 1:
The patent segments the collimation function across two acylindrical lenses oriented at right angles to each other. Each lens handles one principal axis of the astigmatic beam, eliminating the focal point misalignment issue that plagues single-lens solutions.
Solution Approach 2:
Each acylindrical lens is designed with specific local optical properties tailored to its designated axis. The first lens has collimation properties optimized for the fast axis, while the second lens has properties optimized for the slow axis, allowing precise control over beam characteristics in each direction.
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 bi-acylindrical lens system effectively transforms the divergent elliptical light beam into a round collimated beam, addressing the astigmatic emission of laser diodes and meeting the requirement for a circular beam in various applications.
Implementation Method 1
When placing an aspherical collimating lens in front of a laser diode, the resulting beam typically focuses at different locations in the X and Y directions
Data Source
AI summary
A bi-acylindrical lens collimates a divergent elliptical laser beam. A first surface of the bi-acylindrical lens is shaped to form a first acylindrical lens, and a second surface of the bi-acylindrical lens is shaped to form a second acylindrical lens. The first acylindrical lens collimates the divergent elliptical laser beam on the fast axis, and the second acylindrical lens collimates the diverging elliptical laser beam on the slow axis.