Widefield Photothermal Chemical Imaging for Infrared Absorption
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Solution Overview
Problem
Existing vibrational imaging techniques face limitations in spatial resolution and acquisition speed, particularly in mid-IR imaging, which is insufficient for resolving microstructures in biological samples and unsuitable for routine use in aqueous environments.
Innovation Solution
A system utilizing a pump source, probe source, and camera synchronized to detect photothermal effects through synchronized pump and probe pulse trains, enabling ultrafast chemical imaging with sub-micrometer resolution and depth resolution using a visible laser to probe IR absorption-induced thermal lensing effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mid-IR imaging is used to achieve larger absorption cross sections and adequate sensitivity, then sensitivity is improved, but spatial resolution deteriorates to several to tens of micrometers which is insufficient for resolving microstructures
Solution Approach 1:
The patent uses a visible probe beam as an intermediary to detect the thermal effects caused by mid-IR absorption. The mid-IR pump beam heats the sample, and the visible probe beam measures the temperature-induced refractive index changes, allowing indirect detection of mid-IR absorption with high spatial resolution.
Solution Approach 2:
The patent replaces the direct mechanical detection method (AFM cantilever) with an optical detection method using visible laser probe and camera system, eliminating the mechanical contact while achieving comparable or better spatial resolution and acquisition speed.
2Manufacturing precision
If AFM-IR technique is used to achieve nanoscale localization and high spatial resolution chemical mapping, then spatial resolution is improved, but acquisition speed deteriorates due to tip-based imaging modality
Solution Approach 1:
The patent replaces the mechanical AFM tip scanning system with a widefield optical imaging system using visible laser and camera, enabling parallel detection across the entire field of view and achieving acquisition speeds up to 1250 frames per second while maintaining sub-micrometer spatial resolution.
Solution Approach 2:
The patent transitions from one-dimensional tip scanning to two-dimensional widefield optical imaging, allowing simultaneous measurement of multiple spatial locations and dramatically increasing acquisition speed through parallel detection.
3Measurement precision
If conventional FTIR instrumentation is used with interferometry and globar excitation, then sensitivity is achieved, but acquisition speed deteriorates and it is unsuitable for routine use in aqueous environments
Solution Approach 1:
The patent uses pulsed mid-IR laser excitation instead of continuous globar illumination, enabling time-resolved detection and synchronization with the camera frame rate, which dramatically increases acquisition speed to 1250 frames per second.
Solution Approach 2:
The patent introduces a visible probe beam as an intermediary to detect thermal effects, replacing the direct IR detection method and enabling high-speed camera-based detection that is insensitive to water absorption interference.
4Manufacturing precision
If near-field approach with AFM is used to surpass fundamental limitations, then spatial resolution is improved to nanoscale, but device complexity increases due to sophisticated set-up and data processing procedure
Solution Approach 1:
The patent replaces the complex mechanical AFM positioning and scanning system with a simple widefield optical imaging setup using standard microscope objectives and cameras, dramatically reducing device complexity while maintaining high spatial resolution through optical sectioning.
Solution Approach 2:
The patent uses a universal visible laser and camera system that can be integrated with standard microscope equipment, making the technique accessible and easy to implement without requiring specialized near-field apparatus or complex data processing procedures.
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
Achieves ultrafast chemical imaging at 1250 frames per second with sub-micrometer resolution, suitable for live cell imaging and non-transparent samples, filling the gap between FTIR and AFM-IR microscopy.
Implementation Method 1
detect photothermal effects through synchronized pump and probe pulse trains, enabling ultrafast chemical imaging with sub-micrometer resolution and depth resolution using a visible laser to probe IR absorption-induced thermal lensing effects
Implementation Method 2
A system utilizing a pump source, probe source, and camera synchronized to detect photothermal effects through synchronized pump and probe pulse trains
Implementation Method 3
using a visible laser to probe IR absorption-induced thermal lensing effects
Data Source
AI summary
Systems and methods for detecting photothermal effect in a sample are described herein. In these systems and methods, a pump source is configured to generate a pump pulse train, a probe source is configured to generate a probe pulse train and is synchronized with the pump pulse train, and a camera collects the resulting data. The camera is configured to collect a first signal corresponding to a hot frame, wherein the hot frame includes visible probe beam as modified by a pump beam and a second signal corresponding to a cold frame, wherein the cold frame includes visible probe beam that has not been modified by a pump beam. A processor can subtract the second signal from the first signal to detect the photothermal effect.