Pump-Probe Cantilever Measurement for Photoexcitation Dynamics
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Solution Overview
Problem
Existing measurement systems, such as STM and AFM, are limited in their ability to measure photoexcitation dynamics.
Innovation Solution
A measurement system incorporating a first and second laser device, a trigger generator and delay time controller, an auxiliary optical system, a cantilever with a probe tip, and a controller, which uses a lock-in amplifier to measure optical excitation dynamics by applying a periodically varying voltage to the cantilever and detecting changes in resonance frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a light source unit is added to an existing microscope unit to enable photoexcitation dynamics measurement, then measurement capability for optical excitation dynamics is improved, but device complexity increases
Solution Approach 1:
The patent combines a pump light source unit with an existing microscope unit to create an integrated measurement system. The pump light unit includes a laser device, delay time controller, and optical components that are merged with the microscope's optical path, enabling photoexcitation dynamics measurement without requiring a completely separate system.
Solution Approach 2:
The measurement system is designed to perform multiple functions: it can conduct both conventional microscope observations and photoexcitation dynamics measurements using the same basic microscope structure. The added light source unit enables the system to measure optical excitation dynamics while maintaining compatibility with existing microscope operations.
2Measurement precision
If pulse laser devices and delay time controllers are added to enable time-resolved measurements, then measurement precision for photoexcitation dynamics is improved, but device complexity increases
Solution Approach 1:
The system uses periodic pulse laser excitation with controlled delay times to enable time-resolved measurements. The delay time controller periodically varies the delay between pump and probe light pulses, allowing the system to capture dynamic processes at different time points with high precision.
Solution Approach 2:
The measurement system maintains continuous operation by repeatedly cycling through pump light excitation, delay time variation, and signal detection. The lock-in amplifier continuously processes signals while the delay time controller continuously adjusts pulse timing, ensuring uninterrupted data collection for high-precision measurements.
3Measurement precision
If lock-in amplifier and delay time controller are used to enhance signal detection, then signal-to-noise ratio is improved, but device complexity increases
Solution Approach 1:
The lock-in amplifier uses feedback mechanisms to continuously adjust and optimize signal detection. It compares the detected signal with reference signals generated by the delay time controller, amplifying only the components that match the expected pattern while rejecting noise, thereby improving the signal-to-noise ratio through active feedback processing.
Solution Approach 2:
The delay time controller acts as an intermediary between the pulse laser devices and the lock-in amplifier. It generates precise timing signals and reference pulses that mediate the interaction between the optical components and the detection system, enabling coherent signal extraction at high signal-to-noise ratios.
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 the measurement of optical excitation dynamics by adding a light source unit to existing microscopes, allowing for time-resolved measurements with high signal-to-noise ratio and versatility in complex environments.
Implementation Method 1
measuring, by the lock-in amplifier, the change-amount signal by phase-sensitive detection using reference signal
Implementation Method 2
applying a periodically varying voltage to the cantilever and outputting a change amount signal which is a voltage or a current corresponding to a change in the resonance frequency of the cantilever
Implementation Method 3
a first laser device for outputting a pump light as a pulse laser in response to an input first signal; a second laser device for outputting a probe light as a pulse laser in response to an input second signal
Data Source
AI summary
A measurement system includes: a first laser device for outputting a pump light as a pulse laser in response to an input first signal; a second laser device for outputting a probe light as a pulse laser in response to an input second signal; a trigger generator and delay time controller for inputting the first signal and the second signal to the first laser and the second laser, repeatedly inputting the first signal and the second signal by switching a variable delay value which is a difference between a timing of inputting the first signal to the first laser and a timing of inputting the second signal to the second laser in a plurality of ways, and outputting a reference signal to a lock-in amplifier when switching the variable delay value; an auxiliary optical system for guiding the pump light and the probe light to sample; a cantilever having an probe tip disposed proximate to the sample; and a controller for applying a periodically varying voltage to the cantilever and outputting a change amount signal which is a voltage or a current corresponding to a change in the resonance frequency of the cantilever, wherein the lock-in amplifier measures the change amount signal based on reference signal.