Observation Device Doppler Shift Phase Imaging
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Solution Overview
Problem
Existing observation devices using phase shift methods struggle to obtain phase images of moving objects due to the need for high-speed imaging with photodetectors that are expensive or have poor spatial resolution, resulting in low image quality and sensitivity.
Innovation Solution
The observation device employs a light source and a detection unit that utilizes a Doppler shift effect to generate scattered light, which is then processed using a specific Fourier transform method to obtain a phase image of a moving object, even with a photodetector having a slow read-out speed per pixel, improving SN ratio and sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a two-dimensional photodetector array with high frame rate is used to capture four two-dimensional images for phase shift method, then a phase image of a moving object can be obtained, but the photodetector becomes expensive and has poor spatial resolution
Solution Approach 1:
The patent segments the detection process by using a one-dimensional photodetector array instead of a two-dimensional array, and separates the measurement of phase information from spatial information. The phase shift is measured over time at each position, allowing phase information to be extracted without requiring high-speed two-dimensional imaging.
Solution Approach 2:
The patent transitions from two-dimensional spatial detection to one-dimensional spatial detection combined with temporal measurement. By adding the time dimension for phase measurement, the system achieves phase imaging capability without requiring high frame-rate two-dimensional detection, thus resolving the contradiction between speed and spatial resolution.
2Speed
If a two-dimensional photodetector array with high frame rate is used to capture four two-dimensional images, then phase image of moving object can be obtained, but the image quality and sensitivity become poor
Solution Approach 1:
The patent segments the detection approach by using a one-dimensional photodetector array and measuring phase information temporally at each position. This segmentation allows for longer exposure times at each measurement point, improving signal-to-noise ratio and image quality while maintaining the ability to capture moving objects.
Solution Approach 2:
The patent employs dynamic phase shifting by moving the object through a known trajectory while measuring intensity variations over time at fixed positions. This dynamic approach allows phase information to be extracted from temporal intensity variations, improving measurement reliability for moving objects without requiring high-speed imaging.
3Measurement precision
If phase shift method is used to obtain quantitative information, then amplitude and phase images can be obtained, but four two-dimensional images must be captured requiring the object to stand still
Solution Approach 1:
The patent transforms the static phase shift method into a dynamic measurement approach. By measuring intensity variations over time at each position of a one-dimensional array as the object moves, the system extracts phase information without requiring the object to remain stationary, thus maintaining quantitative measurement capability while eliminating the stability requirement.
Solution Approach 2:
The patent adds the time dimension to the measurement process, transitioning from capturing four simultaneous two-dimensional images to measuring intensity variations over time at each position. This temporal dimension allows phase information to be extracted through temporal analysis, eliminating the need for object stability while maintaining quantitative measurement precision.
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 allows for the acquisition of phase images of moving objects at higher speeds and enhances the signal-to-noise ratio and sensitivity, effectively overcoming the limitations of existing technologies.
Implementation Method 1
a direction on a predetermined plane yielding a fixed Doppler shift effect caused by a movement of the object in light having reached the predetermined plane in scattered light generated by the object upon irradiation with the light by the light source
Data Source
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AI summary
Provided is an observation device which can obtain a phase image of a moving object rapidly with high sensitivity even when using a photodetector having a slow read-out speed per pixel. The observation device 1 comprises a light source 10, a first modulator 20, a second modulator 30, a lens 40, a beam splitter 41, a photodetector 46, and an arithmetic unit 50. The lens 40 receives scattered light generated by a moving object 2 and forms a Fourier transform image of the object 2. The photodetector 46 outputs data representing a sum in a v direction of data temporally changing at a frequency corresponding to a Doppler shift frequency of the light having reached each position on a light-receiving surface through the lens 40 at each position in a u direction at each time. The arithmetic unit 50 obtains an image of the object 2 according to the output of the photodetector 46.