Multispectral Laser Scanner with Frequency-Selective Combining
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Solution Overview
Problem
Conventional laser scanners face challenges in merging geometric and radiometric data due to differing spatial and temporal resolutions, and suffer from color errors and noise multiplication when trying to capture multispectral signatures, especially under varying lighting conditions.
Innovation Solution
A laser scanner design that combines radiometric measurement channels via a frequency-selective combiner, eliminating the need for bandpass filters and allowing simultaneous scanning of all spectral channels, which reduces noise and compensates for component tolerances and temperature drifts, enabling precise multispectral data acquisition independent of ambient lighting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate sensors are used for geometric (TLS) and radiometric data (multispectral photographs), then both types of data can be acquired, but the spatial and temporal resolution differ causing merging problems
Solution Approach 1:
The patent combines geometric and radiometric measurement channels into a single integrated laser scanner system with a common optical beam path, eliminating the need to merge data from separate sensors and resolving spatial-temporal resolution mismatches
2Ease of operation
If conventional spectral cameras operate passively at greater distances, then radiometric data can be captured, but the results depend on ambient lighting conditions
Solution Approach 1:
The patent uses actively illuminated measurement with modulated laser beams at specific frequencies, enabling reliable radiometric data capture independent of ambient lighting conditions by using self-generated periodic light sources
Solution Approach 2:
The patent replaces passive optical detection with active laser illumination and phase-based distance measurement, substituting ambient light dependency with controlled active illumination
3Adaptability or versatility
If three RGB laser diodes are used to capture color information, then color data can be acquired, but component tolerances and temperature changes cause color errors
Solution Approach 1:
The patent uses a common signal path with frequency-selective combining and phase evaluation to monitor and correct for component tolerances and temperature drifts, maintaining color accuracy despite environmental changes
4Adaptability or versatility
If bandpass filters are used for different modulation frequencies in separate channels, then color information can be separated, but different delays occur causing color errors
Solution Approach 1:
The patent merges all spectral channels into a common signal path after detection, using frequency-selective combining to separate channels without introducing differential delays, eliminating the timing mismatch problem of separate filtered channels
5Adaptability or versatility
If multiple separate measurement channels are used for different wavelengths, then multispectral data can be acquired, but the device complexity and size increase
Solution Approach 1:
The patent combines multiple spectral measurement channels into a single common signal path using frequency-selective combining, reducing device complexity and size while maintaining full multispectral measurement capability through shared optical and electronic components
6Device complexity
If all wavelengths are mapped onto one photodiode, then device size is reduced, but measurement noise multiplies
Solution Approach 1:
The patent uses frequency-modulated laser beams with distinct modulation frequencies for each wavelength, allowing a single photodiode to resolve multiple wavelengths through frequency discrimination, reducing device size without noise multiplication
Solution Approach 2:
The patent replaces multiple physical detection channels with a single photodiode using frequency-based signal separation, achieving compact integration while maintaining signal-to-noise ratio through electronic frequency filtering
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 the accuracy and reliability of multispectral data acquisition, allowing for precise material differentiation and segmentation, and reduces the complexity and size of the device while improving signal-to-noise ratio and synchronization of measurements.
Implementation Method 1
several laser diodes of different wavelengths, the laser beams of which are directed onto the object to be measured
Implementation Method 2
The measurement beams reflected from the object are fed to a common evaluation processor via similarly constructed optoelectronic measurement channels... each consisting of a photodiode... a bandpass filter (matched to the respective modulation frequency)
Implementation Method 3
The sensor for acquiring the radiometric data has several laser diodes of different wavelengths... The measurement beams reflected from the object are fed to a common evaluation processor via similarly constructed optoelectronic measurement channels (one for each color), each consisting of a photodiode
Implementation Method 4
a combiner is provided via which at least all radiometric measurement channels are selectively and section by section added to a single signal path... only the frequency ranges containing the different measurement signals are selected and added, so that measurement noise from the individual channels is not superimposed
Data Source
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AI summary
Revealbart is a multispectral laser scanner for spatial and radiometric data acquisition.