Laser Pulse Synchronization for Background-Free Optical Signal Detection
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Solution Overview
Problem
Existing optical evaluation methods using laser pulses face challenges in distinguishing desired optical signals from background noise, particularly in high-speed imaging applications like laser scanning microscopy, due to the limited dynamic range of detectors and the inefficiency of the lock-in technique.
Innovation Solution
The method involves generating pulse sequences where two types of excitation laser pulses interact with a sample at specific temporal correlations, allowing for background-free detection by forming differences in signals using synchronized lasers with adjusted repetition rates and pulse synchronization techniques, such as pulse picking and beam splitting, to isolate the desired optical signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the lock-in technique is used to detect optical signals, then measurement precision is improved, but productivity deteriorates due to significant slowdown in image acquisition
Solution Approach 1:
The patent applies periodic action by using pulsed laser excitation instead of continuous illumination. The laser source emits periodic pulses that excite the sample at specific intervals, enabling time-resolved detection. This periodic excitation allows the system to capture signals at optimal moments while maintaining high frame rates, thus improving both measurement precision and productivity.
Solution Approach 2:
The patent implements preliminary action by pre-synchronizing the laser pulses with the detector timing. The system prepares the detection window in advance based on the known pulse timing, allowing the detector to be ready to capture the signal immediately when it arrives. This eliminates the need for slow sequential scanning and enables high-speed image acquisition while maintaining precise signal detection.
2Measurement precision
If two laser pulses are used to produce desired optical signal, then measurement precision is improved by eliminating background noise, but device complexity increases
Solution Approach 1:
The patent merges the two separate laser sources into a single synchronized pulsed laser system. Instead of using two independent lasers that would require complex alignment and synchronization, the invention uses one laser that emits pulses at precisely timed intervals. This combining approach maintains the ability to generate the desired optical signal while significantly reducing system complexity.
Solution Approach 2:
The patent makes a single laser source perform multiple functions that previously required two separate lasers. The pulsed laser both excites the sample and provides the timing reference for detection, eliminating the need for separate synchronization electronics and reducing overall system complexity while maintaining measurement precision.
3Measurement precision
If pulse sequences with temporal correlations are used, then detection precision is improved by isolating desired signals, but ease of operation deteriorates due to complex pulse synchronization requirements
Solution Approach 1:
The patent implements self-service by designing a system where the laser pulse timing automatically serves as the synchronization reference for the detector. The laser's inherent pulse structure provides the timing signal that triggers the detection window, eliminating the need for external synchronization electronics or complex manual timing adjustments. This makes the system easier to operate while maintaining precise signal isolation.
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
This approach enables accurate and efficient detection of optical signals without relying on the lock-in technique, significantly improving image acquisition speed in applications like laser scanning microscopy by separating desired signals from background noise.
Implementation Method 1
frequency doubling, frequency multiplication, sum frequency mixing, difference frequency mixing
Implementation Method 2
sum frequency mixing
Implementation Method 3
difference frequency mixing
Implementation Method 4
CARS (coherent anti-Stokes Raman scattering)
Implementation Method 5
stimulated fluorescence
Implementation Method 6
stimulated Raman scattering, i.e. stimulated Raman gain or stimulated Raman use loss
Data Source
Figure 1
Figure 2(a)~2(g)
Figure 3
AI summary
The method involves directing a set of laser pulses of one type and another set of laser pulses (12) of another type onto a sample (P) to be examined. The laser pulses hit the sample synchronously, within a very short time lag between the two laser pulses, or in a time-correlated manner to produce an optical signal. The signal is detected by detectors (D1-D3). Electronic differentiation between the two set of pulses and third set of pulses, which does not hit the sample synchronously, does not have a time lag between the two laser pulses or not hit in time-correlated manner, is performed. An independent claim is also included for a device for evaluating laser pulses.