Reflective Multispectral Photoacoustic Microscopy Objective

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Solution Overview

Problem

Multispectral photoacoustic microscopy (PAM) systems face challenges in implementing concurrent imaging of endogenous optical absorbers across ultraviolet to near-infrared spectral ranges due to chromatic aberration issues in optics.

Innovation Solution

A multispectral PAM system with a reflective microscope objective having approximately zero chromatic aberration, combined with a customizable ultrasonic transducer for confocal alignment, and a high-repetition-rate wavelength-tunable optical parametric oscillator (OPO) laser, enabling consistent optical focusing and acoustic detection across a broad spectral range.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional refractive microscope objectives are used in multispectral PAM, then the system can cover a broad spectral range, but chromatic aberration degrades optical focusing and imaging quality

Engineering Contradiction:

Improvespectral rangeVSAvoidoptical focusing

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent replaces the refractive optical system with a reflective optical system. Specifically, it uses a reflective microscope objective (mirror-based) instead of a refractive lens-based objective. Reflections are wavelength-independent, eliminating chromatic aberration while maintaining broad spectral coverage from UV to near-infrared ranges.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the fundamental optical parameter from refraction to reflection. By using a reflective objective with a parabolic mirror geometry, the system achieves wavelength-independent focusing across the entire spectral range, transforming the optical behavior to eliminate chromatic dispersion while preserving resolution.

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If optical-acoustic beam combiners are used to align optical and acoustic paths, then confocal alignment can be achieved, but optical aberration and acoustic loss increase

Engineering Contradiction:

Improveconfocal alignmentVSAvoidacoustic loss

Core Design Contradiction:

Ease of operationVSLoss of energy

Solution Approach 1:

The patent merges the optical and acoustic detection paths by integrating the ultrasonic transducer directly into the reflective microscope objective housing. The transducer is positioned in the optical back focal plane, allowing simultaneous optical excitation and acoustic detection without requiring separate beam combiners, thereby eliminating additional optical aberrations and acoustic losses.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent uses the reflective microscope objective itself as the intermediary that simultaneously handles both optical and acoustic functions. The parabolic mirror focuses both light and sound to the same spatial location, eliminating the need for separate alignment mechanisms and reducing energy loss at multiple interfaces.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If multiple separate imaging systems are used to image different endogenous absorbers, then each absorber can be imaged with optimal contrast, but the spatial scale and resolution become inconsistent

Engineering Contradiction:

Improveimaging contrastVSAvoidspatial scale consistency

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent creates a universal imaging system that can simultaneously image multiple endogenous absorbers (DNA/RNA, hemoglobin, lipid) across different spectral ranges using a single reflective microscope objective. The wavelength-independent optical path ensures consistent spatial resolution and scaling for all absorbers, while the transducer detects photoacoustic signals from all targets at the same spatial scale.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 concurrent imaging of cell nuclei, blood vessels, and sebaceous glands at the same spatial scale in vivo with near-constant lateral resolution of approximately 2.8 μm, overcoming chromatic aberration and acoustic loss challenges.

Implementation Method 1

a reflective microscope objective with approximately zero chromatic aberration. The objective may be employed to achieve consistent optical focusing over a broad spectral range

Methodology Applied

Scientific EffectChromatic aberration correction:

Implementation Method 2

Photoacoustic microscopy (PAM) has been used in recent years to satisfy a need in high-resolution imaging of endogenous optical absorption contrasts in vivo

Methodology Applied

Scientific EffectPhotoacoustic effect: Photoacoustic Effect

Implementation Method 3

a high-repetition-rate wavelength-tunable optical parametric oscillator (OPO) laser

Methodology Applied

Scientific EffectOptical parametric oscillation:

Data Source

PatentUS10401327B2Systems and methods for multispectral photoacoustic microscopy

Publication Date: 2019.09.03 UNIV OF VIRGINIA PATENT FOUND

AI summary

A reflection-mode multispectral photoacoustic microscopy (PAM) system and related method is disclosed, based on an optical-acoustic objective in communication with an ultrasonic transducer. In some embodiments of the disclosed technology, when aligned and positioned in a predetermined manner, little to no chromatic aberration is provided, and with convenient confocal alignment of the optical excitation and acoustic detection.