Pulse Measurement Using Passive Replicator for High Dynamic Range
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current pulse measurement technologies, such as streak cameras and oscilloscopes, face limitations in accurately measuring nanosecond-length pulses with high shape contrast due to slow update rates, insufficient vertical resolution, and reduced dynamic range, which hinders real-time monitoring and diagnosis in applications like laser-based inertial confinement fusion.
Innovation Solution
A multi-stage passive pulse replicator system that introduces fixed time delays to input pulses, combined with a repetitively-gated electronic sampling apparatus and processor for temporal alignment and averaging, enhances the dynamic range and signal-to-noise ratio by replicating and averaging pulse trains, allowing for precise measurement of single-shot, high-contrast pulses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If streak cameras or photodiodes with oscilloscopes are used to measure nanosecond-length pulses, then pulse measurement capability is achieved, but update rate is slow and real-time monitoring is limited
Solution Approach 1:
The pulse is replicated multiple times before measurement, creating a train of identical pulses spaced in time. This preliminary replication allows the measurement system to accumulate signal information across multiple pulses, achieving high precision measurement without requiring a fast update rate, thus resolving the contradiction between measurement accuracy and productivity
Solution Approach 2:
The input pulse is copied multiple times through the pulse replication device, creating multiple identical copies spaced in time. These copies are then measured and averaged to improve signal-to-noise ratio and measurement precision while maintaining a manageable update rate, effectively decoupling measurement precision from update rate requirements
2Measurement precision
If conventional averaging techniques are used to reduce noise on periodic signals, then signal-to-noise ratio is improved by N1/2, but non-repetitive single-shot events are washed out and acquisition speed is reduced by factor of N
Solution Approach 1:
The pulse is replicated into a train of N identical pulses spaced in time before measurement. This preliminary replication allows the system to perform averaging on replicated copies rather than requiring N sequential acquisitions, thereby maintaining acquisition speed while achieving the N1/2 signal-to-noise ratio improvement through averaging of the replicated pulses
Solution Approach 2:
Instead of requiring N sequential measurements for averaging, the system creates N copies of the single pulse in time through pulse replication. These copies are then averaged to achieve noise reduction with a single-shot measurement, preserving both signal-to-noise ratio improvement and acquisition speed for non-repetitive events
3Measurement precision
If oscilloscopes are used to measure nanosecond-length pulses with picosecond-scale features, then measurement capability is achieved, but vertical resolution and effective number of bits are insufficient, limiting dynamic range
Solution Approach 1:
The pulse is replicated multiple times before measurement, allowing the oscilloscope to integrate and average the signal across multiple identical pulses. This preliminary replication enables the measurement system to achieve higher vertical resolution and effective number of bits by accumulating signal information, thereby extending the dynamic range capability without requiring a more complex oscilloscope
Solution Approach 2:
Multiple copies of the pulse are created and measured by the oscilloscope. By averaging these copies, the system achieves higher vertical resolution and effective number of bits than the oscilloscope's rated capability, effectively extending dynamic range through signal replication and averaging rather than requiring a higher-end instrument
Data Source
AI summary
An embodiment of the invention is directed to a pulse measuring system that measures a characteristic of an input pulse under test, particularly the pulse shape of a single-shot, nano-second duration, high shape-contrast optical or electrical pulse. An exemplary system includes a multi-stage, passive pulse replicator, wherein each successive stage introduces a fixed time delay to the input pulse under test, a repetitively-gated electronic sampling apparatus that acquires the pulse train including an entire waveform of each replica pulse, a processor that temporally aligns the replicated pulses, and an averager that temporally averages the replicated pulses to generate the pulse shape of the pulse under test. An embodiment of the invention is directed to a method for measuring an optical or an electrical pulse shape. The method includes the steps of passively replicating the pulse under test with a known time delay, temporally stacking the pulses, and temporally averaging the stacked pulses. An embodiment of the invention is directed to a method for increasing the dynamic range of a pulse measurement by a repetitively-gated electronic sampling device having a rated dynamic range capability, beyond the rated dynamic range of the sampling device; e.g., enhancing the dynamic range of an oscilloscope. The embodied technique can improve the SNR from about 300:1 to 1000:1. A dynamic range enhancement of four to seven bits may be achieved.