Inverted CPC Light Collection with Dichroic Filtering

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Solution Overview

Problem

Conventional light detection and ranging systems face inefficiencies in collecting and concentrating light due to the limited acceptance angle of compound parabolic concentrators, leading to reduced light power incident on photodetectors and increased divergence of light rays.

Innovation Solution

The use of upside-down compound parabolic concentrators in conjunction with dichroic filters to limit the angle of incidence and enhance light collection, combined with right-side-up concentrators to increase the field of view and reduce bandpass shifts, effectively concentrating light energy onto photodetectors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If conventional compound parabolic concentrators are used to concentrate light, then light concentration is achieved, but the acceptance angle is limited and light ray divergence increases

Engineering Contradiction:

Improvelight power incident on photodetectorVSAvoidacceptance angle

Core Design Contradiction:

Illumination intensityVSAdaptability or versatility

Solution Approach 1:

The system divides the light collection function into two separate concentrator components: an upside-down CPC for wide-angle light collection and a right-side-up CPC for beam consolidation. This segmentation allows each component to optimize its function, resolving the contradiction between acceptance angle and light concentration.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent inverts the conventional CPC orientation by placing an upside-down concentrator in front of the photodetector. This inverted configuration naturally provides a wider acceptance angle, directly addressing the limitation of conventional right-side-up CPCs while maintaining light concentration capability.

Inventive Principle:

Principle #13The other way round (Inversion)

2Productivity

If conventional compound parabolic concentrators are used, then light concentration is achieved, but system efficiency decreases

Engineering Contradiction:

Improvelight detection efficiencyVSAvoidlight power loss

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The system merges the advantages of both upside-down and right-side-up CPC configurations into a single integrated light collection system. The upside-down concentrator captures light from a wider angular range, while the right-side-up concentrator consolidates the beams, together achieving higher overall efficiency with reduced energy loss.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The right-side-up CPC acts as an intermediary component between the upside-down concentrator and the photodetector. It receives divergent light from the first concentrator, recollimates it, and delivers it to the photodetector, thereby reducing energy loss and improving detection efficiency.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Measurement precision

If dichroic filters are used to filter light, then wavelength selection is achieved, but bandpass shifts occur due to angle of incidence variations

Engineering Contradiction:

Improvewavelength detection accuracyVSAvoidbandpass shift control

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The right-side-up CPC is positioned to pre-collimate the light before it reaches the dichroic filter. This preliminary action reduces the angle of incidence variations at the filter, preventing bandpass shifts and maintaining wavelength detection accuracy without requiring additional complex control mechanisms.

Inventive Principle:

Principle #9Preliminary anti-action

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 configuration increases the light power incident on photodetectors, approaches the efficiency of systems without concentrators, and maintains reduced bandpass shifts, thereby improving the overall performance of light detection and ranging systems.

Implementation Method 1

CPCs are typically used to 'concentrate' light entering the larger aperture into a smaller cross sectional area (the smaller aperture)

Methodology Applied

Scientific EffectLight concentration: Focusing

Implementation Method 2

the light filtered by the dichroic filter is concentrated using a non-imaging concentrator such that the filtered light incident on the photodetector has reduced bandpass shifts

Methodology Applied

Scientific EffectDichroic filtering: Dichroic Filter

Data Source

PatentUS11579427B2Method and apparatus for filtering and filtered light detection

Publication Date: 2023.02.14 MICROVISION INC

AI summary

A non-imaging concentrator is employed in an upside down configuration in which light enters a smaller aperture and exits a larger aperture. The input angle of light rays may be as large as 180 degrees, while the maximum exit angle is limited to the acceptance angle of the non-imaging concentrator. A dichroic filter placed at the larger aperture has a maximum angle of incidence equal to the acceptance angle of the non-imaging concentrator.