Light Guide Optical System for Laser Line Generator
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Solution Overview
Problem
Conventional multiple aperture beam integration optical systems are inefficient and costly when used with high power laser diode bars having a high fill factor, as they require precise alignment of numerous lenses to collect and homogenize coherent light, leading to manufacturing challenges and increased costs.
Innovation Solution
A laser line generator system utilizing a solid integral light guide for total internal reflection and a slow-axis relay lens to produce a homogenous line illumination pattern, reducing the number of optical elements and simplifying assembly, while using a tapered light guide and Keplerian telescope to achieve uniform intensity and sharp edges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional multiple aperture beam integration optical system with microlens arrays is used to collect and homogenize coherent light from high power laser diode bars with high fill factor, then the light collection and homogenization can be achieved, but the system requires precise alignment of numerous lenses leading to very high manufacturing costs and device complexity
Solution Approach 1:
The patent merges multiple separate optical elements (microlens arrays and condenser lenses) into a single integrated light guide structure. This light guide combines the functions of light collection, homogenization, and shaping that were previously distributed across multiple components, thereby reducing device complexity and eliminating alignment issues while maintaining effective light collection and homogenization
Solution Approach 2:
The light guide structure serves multiple functions simultaneously: it acts as a light collector, homogenizer, and beam shaper. This multi-functional design replaces the conventional system requiring separate microlens arrays for collimation and condensation, reducing the total number of optical elements needed while achieving the same overall effect
2Manufacturing precision
If additional lens arrays such as slow-axis collimator telescope microlens arrays are used to avoid light falling on adjacent lenslets, then light direction accuracy is improved, but the number of individual elements that must be fabricated and precisely aligned increases leading to very high system manufacturing costs
Solution Approach 1:
The patent combines the functions of multiple separate lens arrays into a single light guide structure with integrated optical paths. This eliminates the need for precise alignment between multiple lens arrays while maintaining accurate light direction, as the light guide's internal structure inherently guides light to the correct positions without requiring inter-element alignment
Solution Approach 2:
The light guide acts as an intermediary structure that receives coherent light from the laser diode bar and transforms it into homogenized light output. This intermediary structure simplifies the optical path by providing a single interface for light entry and exit, eliminating the complex multi-stage lens array system and its associated alignment and manufacturing challenges
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 system efficiently collects and homogenizes coherent light from high-power laser diode bars, reducing manufacturing costs by three to five times and producing a uniform line illumination pattern with improved edge sharpness and intensity profile.
Implementation Method 1
the coherent light undergoes total internal reflection whenever it impinges on the light guide walls as it propagates through the optical material
Data Source
AI summary
A laser line generator system that utilizes a light guide element to convert high energy coherent light generated by a high fill-factor laser diode bar into homogenous light, and utilizes one or more slow-axis relay lenses to image the homogenous light such that it forms a homogenous line illumination pattern on an illumination plane. The light guide utilizes parallel or down-tapered side walls to mix received coherent light in the slow-axis direction by way of total internal reflection. A Keplerian telescope including two cylinder lenses is optionally used in place of the slow-axis relay lens. Optional fast-axis lenses are used to assist in focusing the homogenous light at the illumination plane. The laser light generator forms, e.g., a single-pass imaging system for a scanning/printing apparatus in which the homogenous line illumination pattern is directed onto a linearly arranged series of spatial light modulators, such as Digital Micromirror Devices (DMDs).