3D Measurement Device Using Polarization Image Sensor
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Solution Overview
Problem
Conventional three-dimensional measurement devices using interferometers face challenges in achieving accurate and efficient phase shift measurements due to manufacturing errors, temperature variations, and intrinsic differences in camera lenses, leading to measurement errors and increased processing complexity.
Innovation Solution
A three-dimensional measurement device employing a polarization image sensor with multiple polarizers of different set angles, where absolute transmission axis angles are measured and stored, allowing for simultaneous acquisition of phase shift data without the need for multiple cameras or optical path adjustments, and using software processing to correct errors without moving optical elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple cameras are used to simultaneously capture interfered lights, then measurement time is reduced, but device complexity and processing load increase
Solution Approach 1:
The patent combines multiple polarizing plates with different transmission axis angles into a single polarization image sensor, allowing simultaneous capture of multiple phase-shifted interfered lights through one imaging device rather than requiring multiple separate cameras
Solution Approach 2:
The polarization image sensor performs multiple functions by simultaneously capturing interfered lights with different phase differences through its array of polarizing plates, eliminating the need for multiple specialized cameras
2Measurement precision
If wave plates are used to shift phase of reference light, then phase difference is achieved, but manufacturing errors and temperature variations cause measurement errors
Solution Approach 1:
The patent replaces the mechanical/optical wave plate system with a polarization-based system using polarizing plates and a polarizing beam splitter, eliminating the need for physical phase shifting components that are sensitive to manufacturing and temperature errors
Solution Approach 2:
The invention changes the approach from physically shifting phase using wave plates to controlling phase differences through polarization angle variations, which are more stable and less susceptible to environmental factors
3Measurement precision
If phase shift is performed by rotating polarizing plate or changing reference plane position, then phase difference is achieved, but measurement time increases due to multiple sequential operations
Solution Approach 1:
The patent pre-arranges polarizing plates with different transmission axis angles in the polarization image sensor before measurement, eliminating the need for sequential rotation or repositioning operations during the measurement process
Solution Approach 2:
The system continuously captures all phase-shifted interfered lights simultaneously in one exposure, maintaining continuous measurement action rather than requiring sequential operations that interrupt the measurement flow
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 configuration enhances measurement accuracy, simplifies the data acquisition process, reduces processing load, and is less susceptible to temperature-induced errors, providing more precise and efficient three-dimensional measurements.
Implementation Method 1
a polarizing beam splitter configured to divide incident light into two polarized lights having polarizing directions perpendicular to each other
Implementation Method 2
a first quarter-wave plate configured to convert the reference light into circularly polarized light and convert reflected light from the reference plane from circularly polarized light into linearly polarized light
Implementation Method 3
the reference light and the object light emitted from the predetermined optical system are made to interfere with each other
Data Source
AI summary
A three-dimensional measurement device includes: a light emitter; an optical system that splits an incident light, irradiates a measurement object with an object light and irradiates a reference plane with a reference light, and recombines the object and reference lights and emits a combined light; an imaging device that takes an image of a light emitted from the optical system; a storage device that stores transmission axis absolute angle data each obtained by a previous actual measurement of an absolute angle of a transmission axis of each polarizer; and a control device that calculates a phase difference between the reference and object lights based on luminance data of each pixel in luminance image data and the transmission axis absolute angle data of each polarizer corresponding to the pixel, and measures a height of the measurement object at the measurement position.