Laser Pulse Peak Detection Using Shifted Control Signal Timing
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Solution Overview
Problem
Current systems for detecting femtosecond laser pulses are inefficient and costly, often missing pulses or inaccurately capturing peak pulse energy levels due to the high-end analog-to-digital converters required for their short pulse widths.
Innovation Solution
A system that includes a photodiode, circuitry for detecting peak pulse timing, and a method to stretch voltage signals, shift control signal timings, compare sampled voltages, and select optimal timing based on peak pulse detection, allowing for accurate measurement of all emitted laser pulses at lower costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-end analog-to-digital converters are used to detect femtosecond laser pulses, then measurement precision is improved, but device cost increases
Solution Approach 1:
The patent segments the detection process into multiple time bins, sampling the laser pulse at different time points. This allows reconstruction of the pulse waveform and accurate peak detection using lower-cost ADCs that can operate at moderate sampling rates, eliminating the need for expensive high-speed converters.
Solution Approach 2:
The patent performs preliminary signal conditioning and time-domain segmentation before ADC conversion. By pre-processing the optical signal through photodetection and time-bin assignment, the system prepares the data in a form that can be accurately measured by lower-speed, lower-cost converters.
2Measurement precision
If high-end analog-to-digital converters are used to detect femtosecond laser pulses, then measurement precision is improved, but pulses may still be missed or peak energy levels inaccurately captured
Solution Approach 1:
By dividing the pulse detection into multiple time bins and sampling each independently, the system ensures that the peak pulse energy is captured in at least one time bin. This segmentation approach increases reliability by providing multiple measurement opportunities for each pulse event.
Solution Approach 2:
The patent implements feedback mechanisms where detected pulse characteristics are used to adjust detection parameters and identify missed pulses. The system analyzes the distribution of detected pulse energies and uses this information to improve detection accuracy and reliability for subsequent measurements.
3Device complexity
If conventional detection systems are used for femtosecond laser pulses, then system cost is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent uses time-bin segmentation to enable the use of lower-cost ADCs. By sampling at multiple discrete time points rather than requiring continuous high-speed sampling, the system achieves accurate peak detection with moderate-speed converters, reducing overall system cost while maintaining precision.
Solution Approach 2:
The patent changes the detection parameter from continuous high-speed sampling to discrete time-bin sampling. This parameter change allows the use of lower-cost hardware while maintaining measurement accuracy through intelligent sampling strategies and waveform reconstruction algorithms.
4Device complexity
If conventional detection systems are used for femtosecond laser pulses, then device cost is reduced, but pulse detection reliability deteriorates
Solution Approach 1:
By segmenting the detection into multiple time bins, the system increases the probability of capturing each pulse event. Even with lower-cost hardware, the multi-time-bin approach ensures that pulses are reliably detected by providing multiple sampling opportunities across the pulse duration.
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 detection and measurement of femtosecond laser pulses at or above 50 kHz repetition rates, achieving reliable peak pulse energy measurement at a lower cost than current systems.
Implementation Method 1
a photodiode configured to detect pulses (e.g., femtosecond or picosecond pulses) emitted by the laser
Data Source
Figure 1A
Figure 1B
Figure 2A~2B
AI summary
In certain embodiments, a system for detecting a peak laser pulse includes a laser, a photodiode configured to detect pulses emitted by the laser, and circuitry for detecting a peak pulse timing of the laser. The circuitry is configured to receive a periodic series of voltage signals based on laser pulses detected by the photodiode, stretch the voltage signals, and obtain sampled voltages from the stretched voltage signals using periodic control signals. The circuitry is further configured to shift the timing of the periodic control signals, compare the sampled voltages for respective timings of the control signals, and select an optimal control signal timing based on the comparison.