Laser Sensor Diffraction Element Wavelength Adaptation

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Solution Overview

Problem

Conventional laser radiation sensors face challenges in compact design and efficient operation over a broad spectral range due to the wavelength-dependent scaling and spatial distribution changes of diffraction patterns, leading to reduced field of view and detection efficiency.

Innovation Solution

The optical diffraction element, particularly a kinoform, is designed to generate diffraction patterns that rotate with wavelength changes, maintaining consistent pattern extent and order spacing across different wavelength bands, allowing for efficient detection and localization of laser sources over a wide spectral range.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the spectral working range is increased to cover more wavelengths, then the detection capability across different wavelengths is improved, but the ratio of field of view area to total detector area continuously decreases

Engineering Contradiction:
Improvespectral working rangeVSAvoidfield of view area
Core Design Contradiction:
Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The optical diffraction element is designed to generate multiple diffraction orders that are spatially separated and segmented across the detector surface. Each diffraction order corresponds to a specific wavelength range, allowing the detector to cover a broad spectral range while maintaining adequate field of view in each segmented region.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent utilizes the spatial distribution of diffraction orders in multiple dimensions across the detector surface. By arranging diffraction orders of different wavelengths in different spatial locations and orientations, the system expands the spectral coverage into the spatial domain, allowing simultaneous coverage of broad spectrum and adequate field of view through multi-dimensional spatial encoding.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Area of stationary object

If the total detector area is increased to maintain field of view ratio, then the field of view coverage is improved, but the device size and complexity increase

Engineering Contradiction:
Improvefield of view areaVSAvoiddetector size
Core Design Contradiction:
Area of stationary objectVSDevice complexity

Solution Approach 1:

The optical diffraction element introduces dynamic wavelength-dependent spatial modulation. The diffraction pattern dynamically adapts to different wavelengths by rotating and scaling the pattern, which allows compact detector design while maintaining adequate field of view for each wavelength band through dynamic spatial encoding rather than static large-area coverage.

Inventive Principle:
Principle #15Dynamics

3Reliability

If conventional diffraction elements are used, then the detection of laser radiation is achieved, but the detection efficiency decreases at wavelengths deviating from the design wavelength

Engineering Contradiction:
Improvelaser detection capabilityVSAvoiddetection efficiency
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The optical diffraction element is designed with wavelength-adaptive parameters that change according to the incident wavelength. The diffraction pattern rotation angle and scaling factor are parameterized to vary with wavelength, ensuring optimal diffraction efficiency and detection performance across the entire spectral working range, not just at a single design wavelength.

Inventive Principle:
Principle #35Parameter changes

4Loss of information

If the diffraction pattern scales with wavelength, then the wavelength information is encoded, but the unused detector surface area increases

Engineering Contradiction:
Improvewavelength encodingVSAvoidunused detector area
Core Design Contradiction:
Loss of informationVSArea of stationary object

Solution Approach 1:

Instead of allowing the diffraction pattern to simply scale with wavelength (which would waste detector area), the patent encodes wavelength information in multiple dimensions: both the spatial scale and the rotation angle of the diffraction pattern. This multi-dimensional encoding allows compact utilization of the detector surface while preserving complete wavelength information.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 design minimizes unused detector surface, maintains detection efficiency, and enables compact, high-performance laser sensors capable of accurately identifying and localizing laser sources across a broad spectral range.

Implementation Method 1

The optical diffraction element diffracts all incident optical radiation into multiple orders

Methodology Applied
Scientific EffectDiffraction: Diffraction

Implementation Method 2

Kinoforms imprint a phase modulation on the incident light, resulting in the desired interference pattern in the image plane

Methodology Applied
Scientific EffectPhase modulation: Phase Modulation

Implementation Method 3

The path difference experienced by the light as it passes through the structured surface causes a phase shift, which results in destructive or constructive interference to generate the desired light distribution in the image plane

Methodology Applied
Scientific EffectInterference: Interference

Data Source

PatentEP2920603B1Sensor for detecting and localising laser beam sources
Publication Date: 2019.07.17 HENSOLDT SENSORS GMBH
  • EP2920603B1 patent drawingFigure 1~2
  • EP2920603B1 patent drawingFigure 3

AI summary

The invention relates to a sensor for detecting and localising laser beam sources, comprising a beam-sensitive detector (30) which is arranged in the image field of an imaging optic (20), an electronic image treating device (40) which is connected to the detector (30), and an optical diffraction element (10) which is arranged in the beam path. According to the invention, the diffraction properties of the optical diffraction element (10) are such that incident laser light on different wave length strips produce diffraction patterns with different shapes, and the electronic signal evaluation device (40) is designed such that it can detect and evaluate the different forms of the diffraction pattern.