Reflective Photodiode for Compact Laser Module Assembly

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Solution Overview

Problem

Current laser-based systems, particularly in mixed-reality applications, face challenges in reducing their form factor and optimizing component placement, leading to increased size and cost due to the separate use of turning optics and photodiodes.

Innovation Solution

A reflective photodiode is developed, which combines the functions of a photodiode and a turning optic by using a highly reflective coating that allows some light to pass through for absorption while reflecting the majority of the incoming light, enabling it to operate as both a photodiode for measuring laser output and a turning optic for redirecting light, thus reducing hardware requirements and allowing for more flexible placement within the system.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If separate photodiodes and turning optics are used in laser-based systems, then the functions of light measurement and light redirection are performed, but the system size and component count increase

Engineering Contradiction:

Improvecomponent countVSAvoidsystem robustness

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent combines the photodiode and turning optic into a single integrated component. The photodiode is positioned at a 45-degree angle to serve dual functions: measuring laser light intensity and redirecting the light path. This eliminates the need for separate turning optics, reducing component count while maintaining system functionality and robustness

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The photodiode is designed to perform multiple functions simultaneously. It acts as both a light detection device for measuring laser output and a light redirecting element through its 45-degree positioning. This multi-functionality reduces the overall component count while ensuring the system remains robust through integrated design

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Volume of moving object

If traditional separate components are used, then each component can be optimized independently, but the overall system form factor increases

Engineering Contradiction:

Improvesystem form factorVSAvoidcomponent optimization flexibility

Core Design Contradiction:

Volume of moving objectVSEase of manufacture

Solution Approach 1:

By merging the photodiode and turning optic into one component, the patent significantly reduces the system form factor. The integrated design eliminates the space required for separate components and their interconnections, enabling more compact laser-based systems while maintaining manufacturing feasibility through standardized photodiode mounting at 45-degree angles

Inventive Principle:

Principle #5Merging (Combining)

3Adaptability or versatility

If more hardware components are used, then system functionality is enhanced, but cost and complexity increase

Engineering Contradiction:

Improvedesign flexibilityVSAvoidhardware requirements

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The photodiode's dual functionality provides design flexibility by enabling multiple system configurations. The same component can simultaneously perform light measurement and light redirection, allowing for adaptable system designs without adding hardware complexity. This versatility is achieved through the photodiode's strategic positioning rather than additional components

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 enables a more compact and cost-effective laser-based system by integrating the functions of photodiodes and turning optics into a single unit, allowing for accurate feedback control of laser performance and improved design flexibility, leading to a more robust and reliable system.

Implementation Method 1

The reflective coating is disposed on the light receiving surface and is configured to reflect a second portion of the incoming light away from the light receiving surface

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 2

The light receiving surface is configured or structured to absorb a first portion of incoming or incident light that is directed at the reflective photodiode and to convert the first portion into electrical current

Methodology Applied

Scientific EffectPhotoelectric Effect: Photoelectric Effect

Data Source

PatentEP3931919B1Photo-sensing reflectors for compact display module assembly

Publication Date: 2023.05.03 MICROSOFT TECHNOLOGY LICENSING LLC

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Figure 2A

AI summary

Techniques are provided to reduce the form factor of laser-based systems by multi-purposing a photodiode used to help control the output of a laser. A reflective photodiode comprises a light receiving surface and a reflective coating. The light receiving surface is configured to absorb some incident light and to convert it into electrical current. The reflective coating is disposed on the light receiving surface and is configured to reflect some of the incident light away from the light receiving surface. The reflective coating also permits some of the incoming light to pass therethrough for absorption.