Polarization Camera Interferometry for Fast Quantitative Phase Imaging
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Solution Overview
Problem
Conventional observation apparatuses face challenges with difficult optical system adjustments, poor vibration resistance, and time-consuming image acquisition for phase images, particularly in Michelson and Mach-Zehnder interferometers and differential interference contrast microscopes.
Innovation Solution
An observation apparatus using spatially incoherent light, linearly polarized beams, and circularly polarized beams with different rotation directions, combined with a polarization camera to acquire interference images for multiple polarization components, allowing for simultaneous generation of complex amplitude images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a Michelson interferometer or Mach-Zehnder interferometer is used to obtain a phase image, then the quantitativeness of the phase image is improved, but the optical system adjustment becomes difficult and vibration resistance deteriorates
Solution Approach 1:
The patent replaces the mechanical beam splitting and combining system (mirrors, beam splitters) with a spatial light modulator that uses electronic control to modulate the optical path difference. This substitution of mechanical components with an electronically controlled device simplifies optical alignment and improves ease of operation while maintaining measurement precision.
2Measurement precision
If a Michelson interferometer or Mach-Zehnder interferometer is used to obtain a phase image, then the quantitativeness of the phase image is improved, but the vibration resistance deteriorates
Solution Approach 1:
The patent replaces the mechanical beam splitting and combining system with a spatial light modulator that electronically controls the optical path difference. This eliminates sensitive mechanical components that are prone to vibration-induced misalignment, thereby improving vibration resistance and reliability while maintaining the ability to obtain quantitative phase images.
3Measurement precision
If the optical path difference is sequentially set to each value by moving a mirror to acquire multiple interference images, then a phase image can be generated, but the time required for image acquisition increases
Solution Approach 1:
The patent employs a spatial light modulator that can dynamically and rapidly change the optical path difference between the reference and object beams by electronically controlling the phase of light at each pixel. This allows sequential acquisition of multiple interference images with different optical path differences to be performed much faster than mechanical mirror movement, thereby improving image acquisition speed while maintaining phase image generation capability.
Solution Approach 2:
The patent replaces the mechanical mirror movement system with an electronically controlled spatial light modulator. This substitution enables rapid, stepless adjustment of the optical path difference without the inertia and mechanical limitations of moving mirrors, significantly reducing the time required to acquire multiple interference images for phase reconstruction.
4Productivity
If a polarization camera is used to simultaneously acquire multiple interference images, then the image acquisition time is reduced, but the quantitativeness of the phase image deteriorates due to approximation assumptions
Solution Approach 1:
The patent uses a spatial light modulator to dynamically introduce precise, controllable optical path differences for each interference image acquired by the polarization camera. By actively controlling the phase modulation rather than relying on fixed optical path differences, the system can accurately reconstruct phase information from the simultaneously acquired images, improving quantitativeness while maintaining high acquisition speed.
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
Facilitates easy optical system adjustment, improved quantitativeness, and rapid acquisition of complex amplitude images, enhancing vibration resistance and reducing the time required for phase image generation.
Implementation Method 1
a polarizer provided on an optical path of the irradiation optical system, and for inputting the light output from the light source and outputting linearly polarized light
Implementation Method 2
a first prism provided on the optical path of the irradiation optical system and between the polarizer and the observation object, and for inputting light output from the polarizer and outputting two linearly polarized light beams orthogonal to each other
Implementation Method 3
a second prism provided on an optical path of the imaging optical system, and for combining two light beams output from the observation object and outputting light
Implementation Method 4
a polarization conversion element provided on the optical path of the imaging optical system and at a subsequent stage of the second prism, and for inputting the light output from the second prism and outputting two circularly polarized light beams having different rotation directions
Implementation Method 5
light generated in the observation object in response to irradiation of the observation object with the light by the irradiation optical system
Implementation Method 6
an imaging optical system for forming an image by inputting light generated in the observation object
Data Source
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AI summary
An observation apparatus 1A includes a light source 11, a lens 12, a polarizer 13, a first prism 14, a condenser lens 15, an objective lens 21, a second prism 22, a 1/4 wave plate 23, a lens 24, a polarization camera 26, and an analysis unit 40. Each of the first prism 14 and the second prism 22 is, for example, a Wollaston prism or a Nomarski prism. The 1/4 wave plate 23 inputs light output from the second prism 22, and outputs two circularly polarized light beams having different rotation directions. The polarization camera 26 inputs two light beams being circularly polarized in different rotation directions by the 1/4 wave plate 23, and acquires an interference image on an imaging plane for each of three or more polarization components. Thus, an observation apparatus capable of easily adjusting an optical system and obtaining a complex amplitude image with improved quantitativeness in a short time is realized.