Polarization-Sensitive OCT Apparatus Using Passive Optical Elements
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Solution Overview
Problem
Conventional polarization sensitive OCT apparatuses require multiple scans and expensive EO modulators to acquire birefringence information, leading to increased size and cost.
Innovation Solution
An optical image measurement apparatus that generates two measurement lights with different polarization states using a passive optical element, allowing for simultaneous acquisition of information by a single scan, reducing the need for multiple light sources and expensive modulation elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional polarization sensitive OCT apparatuses use multiple scans and EO modulators to acquire birefringence information, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent divides the measurement process into two separate measurement lights with different polarization states (first measurement light and second measurement light), allowing independent detection of polarization components. This segmentation enables acquisition of complete birefringence information through multiple linearly polarized measurements rather than requiring complex real-time polarization modulation.
Solution Approach 2:
The patent employs periodic alternation between first and second measurement lights with different polarization states. By sequentially irradiating the sample with these two measurement lights and detecting their reflected light separately, the system acquires polarization information through periodic measurement cycles, eliminating the need for continuous EO modulation.
2Measurement precision
If conventional polarization sensitive OCT apparatuses perform multiple scans to acquire complete polarization information, then measurement precision is improved, but productivity decreases
Solution Approach 1:
The patent performs preliminary preparation of two measurement lights with specific polarization states before the actual measurement. By pre-configuring the first and second measurement lights with orthogonal or complementary polarization states, the system can acquire complete Jones matrix information in a single scan cycle rather than requiring multiple sequential scans, thus improving measurement efficiency.
Solution Approach 2:
The patent combines the information from first and second measurement lights with different polarization states to acquire complete birefringence information. By merging the detection results of these two measurement lights, the system obtains the full Jones matrix in a single measurement cycle, achieving both high precision and high productivity.
3Measurement precision
If conventional polarization sensitive OCT apparatuses use EO modulators for polarization modulation, then measurement precision is improved, but cost increases
Solution Approach 1:
The patent replaces expensive EO modulators with simpler, lower-cost optical components such as polarizing beam splitters, wave plates, and mirrors. These passive optical elements can be manufactured at lower cost and do not require complex electrical control systems, making the apparatus more economically viable while maintaining measurement precision through careful optical design.
Solution Approach 2:
The patent substitutes the electrical EO modulation system with an optical-based polarization control mechanism using passive optical elements. Instead of using electro-optic modulation requiring high-voltage drivers and complex electronics, the system uses optical polarization division and combination through beam splitters and wave plates, eliminating the need for expensive EO modulators and their associated control systems.
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 the acquisition of more birefringence information with fewer scans and at a lower cost, using simple and inexpensive configurations, while maintaining high spatial resolution.
Implementation Method 1
OCT is a technique that acquires tomographic images of samples using interference of light
Implementation Method 2
light from a light source is divided into two light, i.e. signal light that is irradiated onto the sample and reference light that is reflected by a reference light mirror
Implementation Method 3
second measurement light different from first measurement light is generated using a passive optical element that generates light of second polarization state different from first polarization state
Implementation Method 4
some of biological tissues measured by OCT, such as collagen included in human skins or crystalline lens of human eyeballs, have birefringence
Implementation Method 5
first and second signal light that are acquired from the sample reflecting or scattering the first and the second measurement light are detected and then are outputted in a form of an electric signal
Data Source
AI summary
Exemplary embodiments relate to providing an optical image measurement apparatus that is capable of acquiring information on birefringence of a sample while suppressing size and cost of the apparatus. In the present disclosure: second measurement light different from first measurement light is generated using a passive optical element that generates light of second polarization state different from first polarization state; a time when the first measurement light is irradiated onto a sample is adjusted at a first time, and a time when the second measurement light is irradiated onto the sample is adjusted at a second time different from the first time.