Objective Optical System for Photoacoustic Imaging
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Solution Overview
Problem
Conventional photoacoustic imaging apparatuses suffer from acoustic wave attenuation and aberrations due to the separation of light pulses and acoustic signals by a separating member on the objective lens, leading to reduced signal intensity and unclear images, especially when using lenses with large numerical apertures.
Innovation Solution
An objective optical system comprising a convex and a concave mirror configuration with a detector positioned on the object side, allowing the system to be closer to the sample, thus minimizing attenuation and aberrations, and enabling the use of large numerical aperture lenses for improved resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separating member is disposed on the object side of the objective lens to separate light pulse and acoustic signal, then the light pulse and acoustic signal can be separated, but the distance between the objective lens and the sample increases and the acoustic wave is attenuated
Solution Approach 1:
The objective optical system is divided into distinct functional components: a light irradiation unit (objective lens) and an acoustic wave detection unit (acoustic lens), which operate independently without requiring a separating member between them. This segmentation allows each component to be optimized for its specific function while eliminating the need for acoustic wave separation that causes attenuation.
Solution Approach 2:
The patent introduces a reflective member (mirror) as an intermediary component that redirects light onto the sample from the side opposite to the objective lens. This allows the light source and detector to be positioned on the same side of the sample, eliminating the need for a separating member and maintaining close proximity between the objective lens and sample.
2Reliability
If a separating member is disposed on the object side of the objective lens, then light pulse and acoustic signal can be separated, but aberrations occur in the photoacoustic imaging system
Solution Approach 1:
The system separates the light irradiation function and acoustic detection function into distinct optical paths and components. The light path uses the objective lens for focusing, while the acoustic path uses the acoustic lens for detection, with both operating independently without requiring a separating member that would introduce aberrations.
Solution Approach 2:
A reflective member serves as an intermediary to redirect light onto the sample from the opposite side of the objective lens, allowing the light source and acoustic detector to be positioned on the same side. This eliminates the need for a separating member and prevents aberrations in the acoustic wave path.
3Measurement precision
If an objective lens with large numerical aperture is used to improve resolution, then the resolution improves, but the working distance becomes short making it difficult to use with separating member
Solution Approach 1:
The reflective member acts as an intermediary that enables the use of large numerical aperture objective lenses by redirecting light onto the sample from the opposite side. This configuration allows the objective lens to be positioned very close to the sample (short working distance) while still providing sufficient light illumination through the mirror, thereby achieving high resolution without the constraints of long working distance.
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 system provides clearer sample images with higher resolution by reducing acoustic wave attenuation and aberrations, while maintaining high light utilization efficiency and supporting various wavelength ranges.
Implementation Method 1
a first mirror (101) having a convex reflecting surface for reflecting light traveling toward a sample (SP)
Implementation Method 2
a second mirror (102) having a concave reflecting surface for reflecting the light reflected by the first mirror (101) and irradiating the sample (SP) with the light
Implementation Method 3
detecting an acoustic wave obtained by irradiating the sample with the light
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
An object of the present invention is to provide an objective optical system and a photoacoustic imaging apparatus capable of obtaining a clearer image of a sample than before. The objective optical system (23) includes: a convex mirror (101) having a convex reflecting surface for reflecting pulsed light traveling toward a sample (SP); a concave mirror (102) having a concave reflecting surface for reflecting the light reflected by the convex mirror (101) and irradiating the sample (SP) with the light; and an ultrasonic detector (103) having at least one end portion provided on an object side of the convex mirror (101), and detecting an acoustic wave obtained by irradiating the sample (SP) with the light.