Wavefront Shaper for 3D Refractive-Index Tomography
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Solution Overview
Problem
Conventional methods for measuring 3D refractive-index tomograms, such as those using galvanometer mirrors and Liquid Crystal-based Spatial Light Modulators, face challenges with speed and accuracy due to vibration issues, sample deformation, and high costs, limiting their ability to perform high-speed and precise optical tomography.
Innovation Solution
A method and apparatus utilizing a wavefront shaper, specifically a deformable mirror (DM) or digital micromirror device (DMD), to control the illumination angle and wavefront pattern of incident rays, enabling ultra-high speed and high-precision measurement of 3D refractive-index tomograms by modifying the incident rays and using interferometry to obtain 3D scattering potentials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a galvanometer mirror is used to change incident angles, then the measurement can be performed, but stable control of incident angles is difficult due to microscopic vibrations and exact optical alignment cannot be achieved
Solution Approach 1:
The patent replaces the mechanical galvanometer mirror system with a spatial light modulator (SLM) that uses liquid crystal technology to control the incident angles of plane waves. This substitution eliminates mechanical vibrations and pivot point issues inherent in galvanometer mirrors, providing stable and precise angular control without mechanical moving parts.
Solution Approach 2:
The patent introduces a spatial light modulator as an intermediary device between the light source and the sample. The SLM modulates the phase of incident light to precisely control the angles of plane waves, serving as a mediator that achieves accurate angular control without direct mechanical manipulation of mirrors or samples.
2Measurement precision
If a Liquid Crystal-based Spatial Light Modulator is used to change incident angles, then optical alignment can be achieved, but high-speed tomography cannot be performed due to limit to response speed of liquid crystals
Solution Approach 1:
The patent optimizes the operating parameters of the liquid crystal-based SLM, including wavelength selection and voltage control parameters, to enhance the response speed while maintaining optical alignment precision. By carefully adjusting these parameters, the system achieves a balance between precision and speed suitable for tomography applications.
3Measurement precision
If a LC-SLM is used for tomography measurement, then incident angle control is achieved, but the cost increases significantly making it very expensive
Solution Approach 1:
The patent segments the functional requirements of the system into distinct components: a relatively inexpensive spatial light modulator for angle control, standard optical elements for beam shaping, and computational algorithms for image reconstruction. This segmentation allows the use of cost-effective components while maintaining high measurement precision through the coordinated operation of these segmented functional elements.
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 stable and fast control of incident rays, achieving higher precision and speed than traditional methods, enabling more accurate and efficient measurement of 3D refractive-index tomograms without the limitations of mechanical vibrations and high costs associated with existing technologies.
Implementation Method 1
modifying at least one of an illumination angle and a wavefront pattern of an incident ray through the wavefront shaper
Implementation Method 2
measuring a 2D optical field, which passes through the sample, through an interferometer
Data Source
AI summary
A method and apparatus for measuring 3D refractive-index tomograms using a wavefront shaper in ultra-high speed and high precision is provided. The method includes the steps of modifying at least one of an illumination angle and a wavefront pattern of an incident ray through the wavefront shaper and leading the modified incident ray to a sample, measuring a 2D optical field, which passes through the sample, through an interferometry along at least one or more of the incident rays, and obtaining 3D refractive-index tomograms through measured information of the 2D optical field.