Resonant Piezo-Actuator for High-Speed Optical Scanning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing apparatuses for generating temporally spaced apart light pulses, such as those used in ultra-fast time-resolved spectroscopy, are limited by the maximum achievable scanning speed due to the properties of conventional piezo-actuators and control loop bandwidth, leading to signal distortions and inability to precisely control high-frequency scanning.
Innovation Solution
A mechanical oscillator, excited by a periodic modulation signal, adjusts the resonator length of the lasers, operating in resonant frequency to achieve larger deflections and higher scanning speeds, allowing for precise control of time offsets between light pulses without the limitations of closed-loop control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional piezo-actuators and control loops are used to adjust resonator length, then the system is simple and reliable, but the maximum scanning speed is restricted and signal distortions occur at high frequencies
Solution Approach 1:
The patent applies mechanical vibration by driving the piezo-actuator with a sinusoidal modulation signal at its resonant frequency, causing the actuator to oscillate mechanically. This resonant oscillation enables large-amplitude deflections at high frequencies, achieving scanning speeds in the kHz range while maintaining signal precision through the predictable nature of resonant vibration.
Solution Approach 2:
The patent employs periodic action by applying a sinusoidal modulation signal to the piezo-actuator, creating periodic oscillations in the resonator length. This periodic variation of the resonator length results in periodic modulation of the laser pulse repetition rate, enabling high-speed scanning through the time-zero crossing points while maintaining precise temporal control.
2Manufacturing precision
If the piezo-actuator deflection is increased to achieve larger time offset range, then the scanning range is improved, but the maximum scanning speed is restricted by the actuator's physical limits
Solution Approach 1:
By operating the piezo-actuator at its resonant frequency with sinusoidal modulation, the system achieves large deflection amplitudes without increasing the physical travel limits of the actuator. The resonant oscillation amplifies the effective deflection range, enabling both large time offset ranges and high scanning speeds simultaneously.
Solution Approach 2:
The patent changes the operational parameters of the piezo-actuator by driving it at its resonant frequency rather than using slow, linear control. This parameter change transforms the actuator's response from a slow, limited-deflection mode to a high-speed, large-amplitude oscillatory mode, simultaneously improving both scanning speed and time offset range.
3Speed
If conventional control loops are used to regulate repetition rate, then the system is stable, but the bandwidth limits the achievable scanning speed
Solution Approach 1:
The patent extracts the high-speed scanning function from the closed-loop control system and implements it through open-loop sinusoidal modulation of the piezo-actuator. By separating the scanning function (handled by resonant oscillation) from the stabilization function (handled by the control loop), the system achieves high scanning speeds without being constrained by control loop bandwidth limitations.
Solution Approach 2:
The patent replaces the continuous, bandwidth-limited control loop regulation with periodic sinusoidal modulation for the scanning function. This periodic action at the resonant frequency bypasses the bandwidth constraints of the control loop, enabling high-speed scanning while the control loop maintains overall system stability.
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 a high scanning speed with a large maximum time offset, reducing signal distortions and allowing precise calibration of the time axis, while being economical and compact, with improved performance over conventional systems.
Implementation Method 1
A piezo-actuator carrying a reflective optical element (a mirror) is used as actuating member for setting a time offset. The resonator length of the laser is changed by the translation of the mirror by means of the piezo-actuator
Implementation Method 2
the mechanical oscillator in resonant fashion oscillates at the frequency of the modulation signal
Data Source
AI summary
The invention relates to an apparatus for generating temporally spaced apart light pulses, comprisinga first laser (11) which generates a first sequence (I) of light pulses at a first repetition rate,a second laser (12) which generates a second sequence (II) of light pulses at a second repetition rate, andat least one actuating member which influences the first repetition rate and/or the second repetition rate. It is an object of the invention to provide an apparatus for generating temporally spaced apart light pulses which is improved in relation to the prior art. This object is achieved by the invention by a control element (23) which applies a periodic modulation signal (24) to the actuating member for periodic variation of the first repetition rate and/or the second repetition rate, wherein the actuating member comprises a mechanical oscillator excited by the modulation signal (24), the deflection of said oscillator causing an adjustment in the resonator length of the first laser (11) and/or second laser (12), wherein the mechanical oscillator oscillates in resonant fashion at the frequency of the modulation signal (24). In accordance with the invention, an actuator (e.g. a piezo-actuator) which adjusts the resonator length of the laser is operated in resonant fashion. As a result, a large maximum time offset of the light-pulse sequences (I, II) with, at the same time, a high scanning speed is rendered possible. Moreover, the invention relates to a method for generating temporally spaced apart light pulses.