Miniaturized Optical Head for Confocal Microendoscopy

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Solution Overview

Problem

Current miniaturized optical heads for confocal microendoscopes have limitations in achieving high resolution and sensitivity, particularly for fluorescence imaging in vivo, with issues such as low magnification, poor photon collection, and significant axial and lateral resolution degradation.

Innovation Solution

A miniaturized optical head design featuring a spherical aberration correction block, high numerical aperture, and a combination of converging lenses with small radii of curvature, including a half-ball lens, to optimize excitation and fluorescence signal collection, while minimizing aberrations and parasitic reflections.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If miniaturized optical head design is used for confocal microendoscopy, then device size is reduced and can pass through endoscope working channels, but lateral resolution and axial resolution are significantly degraded

Engineering Contradiction:

Improveoptical head sizeVSAvoidlateral resolution and axial resolution

Core Design Contradiction:

Volume of moving objectVSManufacturing precision

Solution Approach 1:

The optical head is segmented into distinct functional modules: an objective lens for focusing excitation light, a beam splitter for separating excitation and emission paths, and a detector for capturing fluorescence signals. This modular segmentation allows each component to be optimized independently, maintaining high resolution while minimizing overall size to fit within endoscope working channels.

Inventive Principle:

Principle #1Segmentation

2Ease of manufacture

If conventional optical design is used, then ease of manufacture is improved, but sensitivity for photon collection is poor

Engineering Contradiction:

Improveoptical design simplicityVSAvoidsensitivity

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The optical design parameters are optimized by selecting specific refractive indices, curvature radii, and thicknesses for the lens elements. The objective lens uses a combination of positive and negative power elements with carefully controlled parameters to achieve high numerical aperture for improved photon collection sensitivity, while remaining manufacturable with standard optical fabrication techniques.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If high numerical aperture is implemented, then sensitivity for fluorescence collection is improved, but spherical aberration increases

Engineering Contradiction:

ImprovesensitivityVSAvoidaberration control

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The objective lens employs an asymmetric configuration with different curvature radii and thicknesses for the front and rear lens elements. This asymmetric design allows the optical path to be optimized for high numerical aperture operation while compensating for spherical aberration through the complementary optical powers of the asymmetric elements, achieving both high sensitivity and acceptable aberration control.

Inventive Principle:

Principle #4Asymmetry

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 design achieves high spatial resolution and sensitivity, enabling detection of small objects with improved axial and lateral resolution, suitable for real-time laser scanning and compatible with endoscopic applications.

Implementation Method 1

focus an excitation signal conveyed by said bundle of fibers at a focal point of excitation

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 2

optical means making it possible to focus the beam of excitation

Methodology Applied

Scientific EffectOptical focusing: Lens

Implementation Method 3

picking up a back-emitted signal coming from the subsurface excitation focal point

Methodology Applied

Scientific EffectFluorescence: Fluorescence

Implementation Method 4

conveyed by the bundle of fibers in particular towards detection means

Methodology Applied

Scientific EffectOptical coupling: Optical Fibre

Data Source

PatentEP2020896B1Miniaturized optical head with high spatial resolution and high sensitivity, especially for fibred confocal fluorescence imaging

Publication Date: 2013.03.27 MAUNA KEA TECHNOLOGIES

Figure 1~3

AI summary

The invention concerns a miniaturized optical head provided to equip the distal end of a beam of flexible optical fibres scanned by a laser beam, said optical head being designed to come in contact with a sample and to excite said sample confocally; this optical head consisting of means for correcting spherical aberrations and focusing means. According to the invention, the focusing means comprise: at least a first lens (L4) of high convergence associated with a spherical or hemispherical lens (L5) arranged at the distal end of the optical head, and means for correction of the axial and lateral chromatic aberration provided with a single divergent lens (3b) the curvature of which is substantially centred on the pupil of the optical fibre beam and arranged at the exact distance for this pupil for which the conditions of lateral achromatization coincide with the conditions of axial achromatization; this divergent lens being associated with a second convergent lens (L3a) in the form of a doublet (L3).