Structured Light 3D Measurement Thermal Equilibrium

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Solution Overview

Problem

Conventional three-dimensional measurement phase shift methods require multiple images and various frequencies to account for varying object depths, leading to increased thermal effects and limitations due to the modulation transfer function of the lens, which affect measurement speed and accuracy.

Innovation Solution

An apparatus using a projection device to sequentially project structured light beams of different frequencies with the same mean level, allowing the system to reach thermal equilibrium before capturing images, thereby reducing the number of images needed and minimizing thermal influence, and utilizing multiple frequencies to enhance measurement range, resolution, and accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If multiple images are captured to complete three-dimensional modeling, then measurement accuracy is improved, but measurement speed deteriorates

Engineering Contradiction:

Improvethree-dimensional measurement accuracyVSAvoidmeasurement speed

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The patent combines multiple frequency measurements into a single captured image by projecting structured light beams with different frequencies simultaneously. The image capture device captures one image containing information from all frequencies, eliminating the need to capture multiple separate images while maintaining measurement accuracy through multi-frequency analysis

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent uses periodic structured light beams with different frequencies projected in sequence during first and second projection periods. By capturing images during these periodic projections and processing them with phase shift algorithms, the system achieves accurate three-dimensional measurement without requiring excessive numbers of images, thus balancing accuracy and speed

Inventive Principle:

Principle #19Periodic action

2Measurement precision

If higher frequency signals are used to improve measurement resolution, then measurement precision is improved, but thermal effects increase

Engineering Contradiction:

Improvemeasurement resolutionVSAvoidthermal effects

Core Design Contradiction:

Measurement precisionVSTemperature

Solution Approach 1:

The patent performs preliminary actions by first projecting low-frequency structured light beams to allow the optical system to reach thermal equilibrium and enter a steady state. After this preliminary low-frequency projection, the system is thermally stabilized before proceeding to high-frequency projections, preventing thermal effects from degrading the high-frequency signal quality

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent segments the projection process into distinct first and second projection periods. The first period uses low-frequency signals for thermal stabilization, while the second period uses high-frequency signals for high-resolution measurement. This temporal segmentation allows the system to benefit from both low-frequency thermal stability and high-frequency measurement precision without compromising either

Inventive Principle:

Principle #1Segmentation

3Adaptability or versatility

If multiple frequencies are used to measure objects with varying depth, then measurement range is improved, but the number of captured images increases

Engineering Contradiction:

Improvemeasurement rangeVSAvoidnumber of captured images

Core Design Contradiction:

Adaptability or versatilityVSQuantity of substance

Solution Approach 1:

The patent merges multiple frequency measurements into a single captured image by projecting structured light beams with different frequencies simultaneously. The image capture device captures one image containing information from all frequencies, eliminating the need to capture multiple separate images while maintaining measurement accuracy through multi-frequency analysis

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent makes the projection device multi-functional by enabling it to project structured light beams with multiple different frequencies during the same projection period. This universal capability allows a single projection-capture cycle to perform what would traditionally require multiple separate operations, thus expanding measurement range without increasing image quantity

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS11199394B2Apparatus for three-dimensional shape measurement

Publication Date: 2021.12.14 BENANO INC

AI summary

An apparatus for three-dimensional shape measurement is provided, including a projection device, an image capture device, and an image processing device. The projection device sequentially projects a plurality of structured light beams on a scene during a first projection period and a second projection period. The mean level of the structured light beams during the first projection period is the same as the mean level of the structured light beams during the second projection period, and the frequency of the structured light beams during the first projection period is different from the frequency of the structured light beams during the second projection period. The image capture device captures an image of the scene within the projection time of each of the structured light beams. The image processing device obtains a three-dimensional shape of a to-be-measured object in the scene according to the images.