VCSEL Anti-Reflection Micro-Lens Array for 3D Scanning
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Solution Overview
Problem
The emission angle of laser light from VCSEL chips is large, making it difficult to fabricate micro-lenses with high precision and sufficiently reduce the emission angle in surface emitting lasers, which affects the efficiency of three-dimensional scanning applications.
Innovation Solution
An optical device is designed with a substrate having surface emitting laser elements and a micro-lens array, where an anti-reflection structure is implemented between the substrate and the micro-lenses to reduce the emission angle of laser light, using a sub-wavelength structure and energy-curable resin to form the micro-lenses with precise dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a micro-lens is formed on a VCSEL chip substrate to reduce emission angle, then light-collecting efficiency is improved, but manufacturing precision deteriorates due to difficulty in fabricating the micro-lens with high precision
Solution Approach 1:
The patent introduces a separate micro-lens array component as an intermediary element that couples with the VCSEL chip. This micro-lens array is fabricated independently with high precision using photolithography and reflow processes, then bonded to the VCSEL chip substrate. This mediator approach allows the micro-lens to be manufactured with precise control over curvature radius and thickness, solving the manufacturing precision problem while maintaining the light-collecting efficiency benefit.
Solution Approach 2:
The patent divides the laser light source system into two separate components: the VCSEL chip (light source) and the micro-lens array (optical element). This segmentation allows each component to be optimized and manufactured independently, with the micro-lens array being fabricated with high precision through separate photolithography and reflow processes, thereby resolving the manufacturing precision issue while preserving the emission angle reduction function.
2Shape
If the emission angle of laser light is reduced using a micro-lens, then parallel light output is achieved, but the complexity of the device increases due to additional optical elements
Solution Approach 1:
The patent combines the VCSEL chip and micro-lens array into a single integrated optical device through bonding. The micro-lens array is positioned in direct contact with or close proximity to the VCSEL chip substrate, merging the light source and optical element into one compact unit. This reduces the overall device complexity compared to separate components while maintaining the parallel light output function.
Solution Approach 2:
The patent transitions from a two-dimensional VCSEL array to a three-dimensional optical structure by adding the micro-lens array in the vertical dimension. The micro-lenses are formed with specific curvature radii and thicknesses, creating a three-dimensional optical path that directs light in parallel. This dimensional addition achieves the desired light beam shape without significantly increasing lateral device complexity.
3Measurement precision
If multiple optical elements are added to reduce emission angle, then light directionality is improved, but manufacturing precision deteriorates due to alignment difficulties
Solution Approach 1:
The patent merges the VCSEL chip and micro-lens array into a single bonded structure, eliminating the need for separate alignment steps. The micro-lens array is bonded directly to the VCSEL chip substrate with the lenses positioned to correspond to the laser emission positions. This integration ensures automatic alignment between the light source and optical elements, maintaining high light directionality while simplifying manufacturing precision requirements.
Solution Approach 2:
The patent employs a self-alignment mechanism where the micro-lens array is fabricated with lenses at positions that naturally correspond to the VCSEL emission positions. During bonding, the proximity and positional correspondence of the lenses to the emitters enable self-alignment, reducing the need for complex external alignment procedures and maintaining high manufacturing precision.
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 anti-reflection structure effectively reduces the emission angle of laser light, allowing it to exit as parallel light, enhancing light-collecting efficiency and precision in applications like three-dimensional scanning, while also improving manufacturing precision and stability across varying temperatures.
Implementation Method 1
an anti-reflection structure between the substrate and the plurality of optical elements
Implementation Method 2
a plurality of optical elements disposed on the second surface so as to respectively correspond to the plurality of surface emitting laser elements
Data Source
AI summary
An optical device includes: a substrate having a first surface, and a second surface opposite of the first surface; a plurality of surface emitting laser elements provided on the first surface of the substrate and configured to emit light in a direction intersecting the first surface; a plurality of optical elements disposed on the second surface so as to respectively correspond to the plurality of surface emitting laser elements; and an anti-reflection structure between the substrate and the plurality of optical elements.