Eye Incision Depth Detection Using Two-Photon Laser Focusing

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Solution Overview

Problem

Existing optical techniques for high-resolution imaging in biological materials are limited to near-surface measurements due to light scattering and blurring, and traditional methods using one-photon absorption processes are inadequate for determining incision depths beyond shallow depths.

Innovation Solution

A medical system utilizing a laser beam with multiple frequencies and two-photon absorption detection to determine focal point distances and incision depths by adjusting mirrors and beam expanders to focus the laser beam, measuring intensity values, and calculating incision depth based on focal point differences.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional one-photon absorption optical techniques are used, then near-surface imaging is achieved, but imaging depth is limited to less than 100 micrometers due to light scattering and blurring

Engineering Contradiction:

Improveimaging resolutionVSAvoidimaging depth

Core Design Contradiction:

Measurement precisionVSLength of moving object

Solution Approach 1:

The patent changes the fundamental optical parameter from one-photon absorption to two-photon absorption detection. This parameter change enables deep tissue imaging by utilizing the nonlinear optical process where two photons are absorbed simultaneously, allowing the excitation to occur only at the focal point where photon density is sufficient, thereby eliminating out-of-focus light scattering and enabling imaging at depths greater than 100 micrometers while maintaining high resolution

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces traditional mechanical scanning and focusing methods with a nonlinear optical detection system. Instead of physically moving the detector or adjusting focus mechanically through tissue layers, the system uses two-photon absorption which inherently provides optical sectioning and depth discrimination, substituting mechanical depth control with nonlinear optical physics

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If laser beam focusing is adjusted to determine multiple focal point distances, then incision depth measurement precision is improved, but device complexity increases due to multiple mirrors and beam expanders

Engineering Contradiction:

Improveincision depth measurementVSAvoidoptical system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent implements a multi-functional optical system where the same laser beam delivery path and focusing optics serve multiple purposes: delivering the two-photon excitation beam, collecting the emitted photons, and enabling depth measurement through focal point distance determination. The mirrors and beam expanders are not just adding complexity but providing universal functionality that serves both imaging and measurement functions simultaneously

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system incorporates feedback through the detection of emitted photons at different focal point distances. By measuring the intensity of emitted light as the focal point is adjusted to different depths, the system receives feedback about the incision depth and can determine the precise depth by identifying where maximum emission occurs, creating a closed-loop measurement system

Inventive Principle:

Principle #23Feedback

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 precise determination of incision depths and topography in the eye with minimal deviation from prescribed cutting depths, facilitating accurate surgical procedures such as flap or lenticule incisions.

Implementation Method 1

A medical system utilizing a laser beam with multiple frequencies and two-photon absorption detection to determine focal point distances and incision depths

Methodology Applied

Scientific EffectTwo-photon absorption: Absorption (EM radiation)

Implementation Method 2

adjusting mirrors and beam expanders to focus the laser beam, measuring intensity values, and calculating incision depth based on focal point differences

Methodology Applied

Scientific EffectOptical focusing: Focusing

Implementation Method 3

measuring intensity values associated with respective multiple interim focal point distances

Methodology Applied

Scientific EffectLight detection: Photoelectric Effect

Data Source

PatentEP4072400B1System of determining incision depths in eyes

Publication Date: 2025.09.03 ALCON INC

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AI summary

The disclosure provides a system that may: determine first multiple focal point distances associated with respective multiple positions of a plane orthogonal to a laser beam; determine second multiple focal point distances associated with the respective multiple positions via for each position of the multiple positions: determine multiple intensity values associated with respective multiple interim focal point distances, each interim focal point distance greater than each focal point distance of the first multiple focal point distances associated with the position; determine an interim focal point distance respectively associated with a maximum intensity value; and determine a focal point distance as the interim focal point distance; and determine a depth of at least one incision in an eye based at least on differences between each of the second multiple focal point distances and each respective one of the first multiple focal point distances.