Planar Waveguide Spatial Filter for Line-Field Imaging Coherence

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Solution Overview

Problem

Line-field imaging systems, such as optical coherence tomography, face challenges in achieving coherent interference signals due to the inability to guide a line of light through single mode fibers, leading to multiple transverse modes propagating to the detector, which results in noise and reduced image quality.

Innovation Solution

Incorporating a single mode planar waveguide in the interferometric line-field imaging system to image the line of light onto the waveguide in at least one dimension, acting as a spatial filter to maximize fringe amplitude and minimize multiply scattered light, thereby improving sensitivity and coherence.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a line of light is used in line-field imaging systems, then imaging speed and productivity are improved, but multiple transverse modes propagate to the detector causing noise and reduced measurement precision

Engineering Contradiction:

Improveimaging speedVSAvoidinterference signal coherence

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

A planar waveguide is introduced as an intermediary component between the line-field illumination and the detector. The waveguide acts as a spatial filter that selects only the fundamental transverse mode while blocking higher-order modes, thereby maintaining coherent interference signals while preserving the parallel imaging capability

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The planar waveguide provides different optical properties in different spatial dimensions: it confines light in the vertical dimension (selecting single transverse mode) while allowing propagation in the horizontal dimension (preserving line-field parallelism). This local differentiation of optical quality enables simultaneous achievement of mode selection and parallel imaging

Inventive Principle:

Principle #3Local quality

2Measurement precision

If single mode fibers are used to guide light, then measurement precision and coherence are improved, but line-field parallel imaging capability is lost

Engineering Contradiction:

Improveinterference signal coherenceVSAvoidparallel imaging capability

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The patent transitions from one-dimensional single mode fiber confinement to two-dimensional planar waveguide confinement. The planar waveguide confines light in one dimension (vertical) while allowing freedom in the other dimension (horizontal), enabling simultaneous single-mode operation and line-field parallel imaging capability

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Ease of operation

If multiple transverse modes are allowed to propagate, then ease of operation and device complexity are reduced, but noise increases and image quality deteriorates

Engineering Contradiction:

Improvesystem simplicityVSAvoidnoise from multiply scattered light

Core Design Contradiction:

Ease of operationVSObject-generated harmful factors

Solution Approach 1:

The planar waveguide serves as a spatial filter intermediary that selectively transmits only the fundamental transverse mode while attenuating higher-order modes. This filtering action reduces noise from multiply scattered light without requiring complex post-processing or additional filtering components

Inventive Principle:

Principle #24Intermediary (Mediator)

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

The use of a single mode planar waveguide enhances the sensitivity and reduces noise in line-field imaging systems by ensuring only coherent light contributes to the interference signal, leading to improved image quality and reduced susceptibility to multiple scattering.

Implementation Method 1

single mode planar waveguide... imaging the line of light onto the waveguide

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

single mode planar waveguide... reduces the collection of multiple transverse modes

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentUS10113856B2Line-field imaging systems and methods incorporating planar waveguides

Publication Date: 2018.10.30 CARL ZEISS MEDITEC INC

AI summary

Improved line-field imaging systems incorporating planar waveguides are presented. In one embodiment the optics of the system are configured such that a line of light on the light scattering object is imaged to the planar waveguide in at least one dimension. Embodiments where the waveguide incorporates a beamsplitter of an interferometer, where the beam divider and waveguide are referenced to one or more common surfaces, and wherein the source and waveguide are optically coupled, are also considered. In another embodiment, the planar waveguide is in contact or close proximity to the light scattering object.