Digital Holographic Microscope Dual Optical System
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Solution Overview
Problem
Current digital holographic microscopes cannot simultaneously measure fluorescence and phase images in three dimensions with high Signal-to-Noise Ratio (S/N ratio) across all polarization states, including random polarization, and are limited in observing non-fluorescent substances and are cumbersome due to the need for sequential imaging and use of harmful fluorescent molecules.
Innovation Solution
A digital holographic microscope with a dual holographic optical system, one for phase imaging and another for fluorescence imaging, utilizing a double-focus lens with a diffraction grating that separates fluorescence signal light from noise light by polarization dependence, allowing self-interference and focusing at a position deviated from the optical axis to enhance S/N ratio, and using a liquid crystal spatial light modulator for phase modulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If a digital holographic microscope uses fluorescent light for hologram acquisition, then fluorescence information can be obtained, but the S/N ratio deteriorates because fluorescent light is incoherent and difficult to interfere
Solution Approach 1:
A polarizing beam splitter is introduced as an intermediary component to separate the fluorescence signal light into orthogonal polarization components. This enables the incoherent fluorescent light to be processed through interference-based holographic measurement by creating coherent paths through polarization separation, thereby improving the S/N ratio while maintaining fluorescence information acquisition
Solution Approach 2:
The patent changes the polarization state parameter of the fluorescent light by using a quarter-wave plate to convert linearly polarized light into circularly polarized light. This parameter transformation enables the fluorescent light to satisfy the interference conditions required for holographic measurement, resolving the contradiction between obtaining fluorescence information and maintaining high S/N ratio
2Loss of information
If a microscope sequentially acquires fluorescence images and phase images, then both types of information can be obtained, but the measurement time increases and dynamic phenomena cannot be captured
Solution Approach 1:
The patent merges the fluorescence imaging path and the phase imaging path into a single integrated digital holographic microscope system. By using a beam splitter to combine the fluorescence signal light with the reference light, the system can simultaneously acquire both fluorescence and phase information through a single holographic measurement, eliminating the need for sequential imaging and reducing measurement time to capture dynamic phenomena
3Device complexity
If a digital holographic microscope uses conventional optical systems, then the structure is simple, but it cannot achieve three-dimensional measurement with arbitrary focal position adjustment
Solution Approach 1:
The patent replaces the mechanical focal adjustment system with a computational approach. By using a spatial light modulator to modulate the reference light wave and performing back-propagation calculations in the computer, the system can reconstruct images at arbitrary focal positions without mechanical movement, achieving versatile three-dimensional measurement while maintaining relatively simple optical hardware
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
Enables simultaneous three-dimensional measurement of fluorescence and phase images with high S/N ratio across all polarization states, including random polarization, and can observe non-fluorescent substances without the need for harmful dyes, improving imaging speed and detail in bio-applications.
Implementation Method 1
acquiring a phase three-dimensional image of a sample to be observed by object light passing through the sample and reference light which has not passed through the sample by using laser light
Implementation Method 2
the double-focus lens and the diffraction grating both have polarization dependence and separate the fluorescence signal light from the noise light by polarization dependence
Implementation Method 3
a double-focus lens on which a diffraction grating is superimposed, and both the double-focus lens and the diffraction grating have polarization dependence
Implementation Method 4
a fluorescence three-dimensional image is obtained by self-interference of the collected fluorescence signal light
Data Source
AI summary
A digital holographic microscope in which two digital holographic microscopes for detecting a fluorescence image and a phase image, respectively, are combined to be able to three-dimensionally measure a fluorescence image and a phase image at the same time, and perform measurement at a high SN ratio in all the polarization states including random light polarization. A first holographic optical system that, by using laser light, acquires a phase three-dimensional image due to interference light generated by superimposing object light which passes through a sample stage and reference light which does not pass through the sample stage onto each other. A second holographic optical system that, by using fluorescent excitation light, acquires a fluorescence three-dimensional image due to a fluorescence signal light, wherein phase measurement by the first holographic optical system and fluorescence measurement by the second holographic optical system are performed at the same time.