Multi-Wavelength Sensor for Rapid Spectral Scanning

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Solution Overview

Problem

Existing active spectrometers face challenges with varying output power as wavelength is tuned, require long time to obtain spectra, and lack spatial movement of the beam, leading to low illumination power and limited standoff distance.

Innovation Solution

A sensor system that simultaneously transmits multiple wavelengths of light from multiple laser devices onto a single spot, using optical amplifiers and modulators to maintain constant output power and enable rapid spectral scanning, with an optical system for beam steering and spatial selectivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a single-wavelength laser is used for spectral measurement, then the spectral resolution is improved, but the time required to obtain a complete spectrum increases significantly

Engineering Contradiction:

Improvespectral resolutionVSAvoidtime to obtain spectrum

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The spectrum is divided into multiple wavelength segments, each handled by a separate laser device. Multiple lasers with different wavelengths operate simultaneously, with each laser's signal modulated at a unique frequency. This allows parallel measurement of different spectral regions, reducing total acquisition time while maintaining spectral resolution through frequency-domain separation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Each laser device modulates its output at a distinct periodic frequency. This periodic modulation enables the detection system to distinguish between different wavelength components in the composite signal, allowing simultaneous multi-wavelength measurement without cross-contamination of spectral data.

Inventive Principle:

Principle #19Periodic action

2Area of stationary object

If the laser beam is spread over a large area, then the coverage area is improved, but the illumination power at any given portion decreases

Engineering Contradiction:

Improvecoverage areaVSAvoidillumination power

Core Design Contradiction:

Area of stationary objectVSPower

Solution Approach 1:

The large area is divided into multiple smaller illuminated spots, each targeted by a separate laser device. Each laser concentrates its power on a specific spot, maintaining high illumination power locally. The combination of multiple spots covers the entire large area, achieving both high power density and broad coverage simultaneously.

Inventive Principle:

Principle #1Segmentation

3Measurement precision

If the output power is increased to improve signal strength, then the sensitivity is improved, but the risk of eye damage increases

Engineering Contradiction:

ImprovesensitivityVSAvoideye safety risk

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The total optical power is distributed across multiple laser devices, each operating at lower power levels. This segmentation reduces the power density at any single wavelength, lowering the risk of eye damage from concentrated monochromatic radiation. The combined signal from multiple low-power lasers achieves the required sensitivity through coherent or incoherent summation.

Inventive Principle:

Principle #1Segmentation

4Productivity

If multiple wavelengths are transmitted simultaneously, then the spectral scanning speed is improved, but the complexity of the system increases

Engineering Contradiction:

Improvespectral scanning speedVSAvoidsystem complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

Each laser device uses periodic modulation at a unique frequency to encode its wavelength information. This approach replaces complex mechanical wavelength tuning mechanisms with simpler electronic modulation circuits. The periodic signals can be easily separated using frequency-domain processing, reducing overall system complexity while enabling simultaneous multi-wavelength operation.

Inventive Principle:

Principle #19Periodic 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

Enables high-resolution, multi-spectral imaging with improved sensitivity and increased standoff distance, while maintaining eye safety and reducing clutter from ambient light.

Implementation Method 1

each of the transmitter units simultaneously transmits a light beam having a plurality of wavelengths

Methodology Applied

Scientific EffectLight emission: Laser

Implementation Method 2

the optical system directs the light beam from each of the transmitter units onto a same illuminated spot on a probed surface

Methodology Applied

Scientific EffectOptical focusing: Focusing

Implementation Method 3

the optical system collects light from the same illuminated spot and directs the light to the photodetector

Methodology Applied

Scientific EffectPhotoelectric detection: Photoelectric Effect

Data Source

PatentUS9903757B1Active multi-spectral sensor

Publication Date: 2018.02.27 HRL LAB

AI summary

A sensor includes a plurality of transmitter units, a photodetector, and an optical system coupled to the plurality of transmitter units and the photodetector. Each of the transmitter units simultaneously transmits a light beam having a plurality of wavelengths, the optical system directs the light beam from each of the transmitter units onto a same illuminated spot on a probed surface, and the optical system collects light from the same illuminated spot and directs the light to the photodetector.