Active Illumination Wavelength Variation Field Angle

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Solution Overview

Problem

Active illumination-based imaging systems face challenges in effectively rejecting background light while maintaining high signal-to-noise ratios, particularly due to the narrow acceptance angle of narrowband dielectric filters, which limits light throughput and requires large, expensive optical systems.

Innovation Solution

The system employs an emission source with varying wavelengths across the field of view, matching the passband of a detector-side filter, allowing only specific wavelengths to pass through, thereby reducing background interference and increasing acceptance angle without enlarging the optical system.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If narrowband dielectric filters are used to reject background light, then background light rejection is improved, but acceptance angle is reduced and system size increases

Engineering Contradiction:

Improvebackground light rejectionVSAvoidoptical system size

Core Design Contradiction:

Object-affected harmful factorsVSArea of stationary object

Solution Approach 1:

The patent applies local quality by making the filter's optical characteristics (center wavelength and bandwidth) vary across different spatial locations or angles of incidence. Different regions of the filter are optimized for different wavelengths, allowing each region to effectively reject background light at its specific operating angle while maintaining a wide overall acceptance angle for the optical system.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent implements parameter changes by varying the center wavelength and bandwidth parameters of the dielectric filter across different angular ranges or spatial positions. This allows the filter to adapt its spectral characteristics to match the wavelength of interest at each angle, maintaining high background rejection across a wide field of view without requiring a large physical filter size.

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If narrowband dielectric filters are used to reject background light, then background light rejection is improved, but light throughput is reduced

Engineering Contradiction:

Improvebackground light rejectionVSAvoidlight throughput

Core Design Contradiction:

Object-affected harmful factorsVSLoss of energy

Solution Approach 1:

The filter is designed with locally optimized spectral characteristics where each region or angular range has tailored bandwidth and center wavelength parameters. This allows the filter to be narrowband enough to reject background light at each specific wavelength while being wide enough overall to transmit sufficient signal light across the full field of view, maximizing light throughput.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

By dynamically changing the effective bandwidth and center wavelength parameters across different angular ranges, the filter maintains optimal signal-to-noise ratio at each angle while preserving maximum possible light throughput across the entire optical system.

Inventive Principle:

Principle #35Parameter changes

3Object-affected harmful factors

If narrowband dielectric filters are used to reject background light, then background light rejection is improved, but system cost increases

Engineering Contradiction:

Improvebackground light rejectionVSAvoidsystem cost

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The patent reduces system cost by implementing local quality variations in a single filter component rather than requiring multiple separate filters or complex optical systems. The angular-dependent spectral characteristics are achieved through a unified filter design, simplifying manufacturing and reducing overall system cost while maintaining effective background light rejection.

Inventive Principle:

Principle #3Local quality

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 approach enhances light throughput and reduces system size and cost by allowing smaller detector-side filters while maintaining high signal-to-noise ratios and rejecting background light effectively.

Implementation Method 1

one or more light emitter elements (including semiconductor lasers, such as surface- or edge-emitting laser diodes)

Methodology Applied

Scientific EffectLight emission from semiconductor lasers: Laser

Implementation Method 2

a detector-side spectral filter element that is configured to receive return signals having the respective wavelengths corresponding to the optical signals over the respective portions of the field of view

Methodology Applied

Scientific EffectSpectral filtering: Filter (optical)

Data Source

PatentUS20220163634A1Active illumination systems for changing illumination wavelength with field angle

Publication Date: 2022.05.26 SENSE PHOTONICS INC

AI summary

An active illumination apparatus includes an emission source configured to illuminate a field of view. The emission source includes one or more emitter elements, and is configured to output optical signals having respective wavelengths that vary based on respective portions of the field of view to be illuminated thereby. The respective wavelengths of the optical signals may vary over respective field angles of the field of view according to variations in optical characteristics of a detection module, such as a passband of a detector-side spectral filter element, for the respective field angles. Related imaging apparatus and methods are also discussed.