3D Structure Detection Using Asymmetric Laser Illumination
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Solution Overview
Problem
Existing 3D structure detection apparatuses suffer from large space requirements and significant speckle noise due to the use of multiple laser wavelengths at identical angles, which affects the accuracy of surface and object mapping.
Innovation Solution
A compact apparatus using a measuring device to stabilize and measure the wavelengths of laser radiation, ensuring constant wavelengths for interference pattern recording, and employing multiple laser emitters with different angles of incidence to reduce speckle noise, along with a Fabry Perot interferometer for precise wavelength measurement and a micro-optic array for compact optics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple laser wavelengths are used at identical angles of incidence, then measurement precision is improved through interferometric detection, but speckle noise increases causing granular appearance in the detected surface
Solution Approach 1:
The patent applies asymmetry by illuminating the object surface with laser beams at different angles of incidence rather than identical angles. This asymmetric illumination geometry causes the speckle patterns generated by different wavelengths to be spatially distributed differently across the detector, allowing computational methods to distinguish and separate the speckle noise from the true surface topology information, thereby reducing the granular appearance while maintaining interferometric measurement precision
2Measurement precision
If conventional holographic apparatus with multiple lasers and beam splitters is used, then 3D structure detection capability is achieved, but space requirement increases
Solution Approach 1:
The patent merges multiple laser wavelengths into a single composite laser beam that illuminates the object simultaneously. This combining approach eliminates the need for separate optical paths, multiple beam splitters, and complex alignment systems required by conventional holographic apparatus. The merged beam approach achieves 3D structure detection capability while significantly reducing the spatial footprint of the apparatus
Solution Approach 2:
The patent employs a single laser source that generates multiple wavelengths, making this one component perform the function previously requiring multiple separate lasers. This multi-functional approach reduces the number of optical components needed and simplifies the overall apparatus configuration, thereby reducing space requirements while maintaining the ability to detect 3D structures through interferometric methods
3Reliability
If laser wavelengths fluctuate due to temperature variations, then reliability of wavelength-based measurement is improved through continuous measurement, but device complexity increases with additional measuring and control components
Solution Approach 1:
The patent implements a feedback control system where a measuring device continuously monitors the wavelengths of the laser radiation and provides real-time data to a control device. The control device adjusts the laser operation based on this feedback to maintain substantially constant wavelengths. This closed-loop feedback mechanism ensures reliable wavelength-based measurements while automating the compensation for temperature variations and other environmental factors
4Measurement precision
If short exposure time is used to freeze moving objects, then measurement precision is maintained, but signal quality may deteriorate due to reduced light accumulation
Solution Approach 1:
The patent uses periodic modulation of the laser wavelengths, alternating between at least two different wavelengths in a time-varying manner. This periodic action allows the system to accumulate sufficient light signal over multiple cycles while still capturing freeze-frame images at specific moments when the object is stationary or in a known state. The interferometric detection integrates information over these periodic wavelength variations, maintaining measurement precision without requiring excessively long exposure times that would blur moving features
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
The solution enables accurate and compact 3D structure detection with reduced speckle noise, allowing for precise surface and depth information capture, even in confined spaces such as the human mouth, while maintaining high signal quality and reducing computational complexity.
Implementation Method 1
The apparatus comprises at least two laser emitters, in particular two laser diodes, which are located on a common emitter chip
Implementation Method 2
The object beam reflected from the object and the appurtenant reference beam of one wavelength are combined and interfere with one another, the phase relationships between the two beams being recorded
Implementation Method 3
a Fabry Perot interferometer for precise wavelength measurement
Data Source
AI summary
An apparatus for detecting a 3D structure of an object. The apparatus has first and second laser emitters which generate laser radiation having first and second wavelengths, respectively, the first wavelength being different from the second wavelength. Optical devices are disclosed, including a beam splitter, which splits the laser radiation of the laser emitters in each case into a reference radiation and an illuminating radiation. The illuminating radiation impinges upon the object to be measured, is reflected by the object as object radiation and interferes with the reference radiation. A detector receives the interference patterns. The laser emitters are located such that the illuminating radiation of the first and second laser emitters impinge upon the object at different angles of incidence. Also discussed is a measuring device which measures the two wavelengths of the laser radiation of the laser emitters and influences the recording of the interference patterns.