VCSEL Optical Module with Segmented Transparent Layer for Alignment Stability
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Solution Overview
Problem
Compact optical imaging modules in portable devices face challenges in maintaining alignment between imaging optics and image sensors due to mechanical shocks, leading to inaccurate measurements and errors in depth sensing applications.
Innovation Solution
The integration of a micro-prism-lens structure over a semiconductor substrate with a reflective layer and a transparent layer, which internally reflects and collimates the emitted beam from a VCSEL, allowing for a large-diameter, tilted beam with reduced divergence, and the use of dedicated emitters to detect alignment shifts within the optical imaging module.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a microlens is integrated with a VCSEL to direct and collimate the emitted beam, then beam collimation is improved, but alignment stability deteriorates due to mechanical shocks causing misalignment between the microlens and VCSEL
Solution Approach 1:
The transparent layer is divided into two functional segments: a first segment (curved outer surface) that internally reflects the emitted beam toward the reflective layer, and a second segment (flat or planar outer surface) that collimates and transmits the reflected beam. This segmentation allows each segment to perform its specific function independently, maintaining beam collimation while reducing sensitivity to alignment shifts between the VCSEL and the transparent layer.
Solution Approach 2:
Instead of using a conventional microlens that directly collimates the beam from the VCSEL, the patent inverts the approach by using a transparent layer with a curved outer surface that first internally reflects the beam toward a reflective layer, which then reflects it back through the transparent layer for collimation. This inverted configuration reduces alignment sensitivity while maintaining collimation performance.
2Measurement precision
If alignment detection methods are added to detect misalignment, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The transparent layer serves multiple functions: it acts as a protective cover over the VCSEL, provides beam direction through its curved outer surface via internal reflection, and enables alignment detection by maintaining a stable optical path. This multi-functionality reduces the need for additional dedicated alignment detection hardware, thereby limiting the increase in device complexity.
Solution Approach 2:
The transparent layer's stable optical path and integrated structure enable the system to self-detect alignment issues through changes in the reflected beam pattern, without requiring external alignment detection devices. The structure itself provides the means for detecting misalignment, reducing hardware complexity.
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 solution enhances the accuracy of optical imaging modules by maintaining beam collimation and alignment, reducing errors in measurement applications and enabling corrective actions for alignment shifts, while minimizing hardware additions to existing module designs.
Implementation Method 1
The first segment is configured to internally reflect the emitted beam of light toward the reflective layer by total internal reflection (TIR)
Implementation Method 2
the second segment positioned and configured to collimate and transmit the beam reflected from the reflective layer
Data Source
AI summary
An opto-electronic device includes a semiconductor substrate having a planar surface. An emitter is formed on the substrate and configured to emit a beam of light away from the planar surface. A reflective layer is formed on the planar surface adjacent to the emitter. A transparent layer is formed over the planar surface and has a curved outer surface including a first segment positioned vertically over the emitter and configured to internally reflect the emitted beam of light toward the reflective layer, and a second segment positioned and configured to collimate and transmit the beam reflected from the reflective layer.