Optical Scanning via Acoustic Wave Delay Line
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Solution Overview
Problem
Existing devices for generating time-separated light pulses, such as mode-coupled lasers and ASOPS techniques, face limitations in time resolution and scanning range, leading to inefficient scanning times and unusable measurement data due to mechanical mirror adjustments and large scanning ranges.
Innovation Solution
A device that uses a phase regulation loop to adjust the repeat frequency of light pulse sequences, allowing precise control of the time offset between light pulse sequences using a phase detector and regulator, with a cycle signal source to determine and set the desired phase value, enabling flexible scanning ranges and improved time resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an electromechanically moved mirror is used to vary the delay distance in one arm of the interferometer, then the time interval between light pulses can be adjusted, but the mirror movement is relatively slow causing correspondingly slow variation of the time interval and undesirably long scanning times
Solution Approach 1:
The patent replaces the electromechanical mirror system with an acoustic wave system. Acoustic waves are generated in a delay line medium (such as a solid rod or bar) to create expanding and contracting wave patterns that modulate the optical path length. This acoustic-based approach eliminates the mechanical moving parts and achieves much faster modulation speeds in the megahertz range, directly resolving the contradiction between adjustability and scanning speed.
2Adaptability or versatility
If an electromechanically moved mirror is used to adjust the delay distance, then the time interval between light pulses can be varied, but the mechanical mirror adjustment is susceptible to incorrect settings and brings about an undesirable variation in the beam diameter caused by the divergence of the light beam
Solution Approach 1:
The patent eliminates mechanical mirrors entirely by using acoustic waves to modulate the optical path. The acoustic waves are generated by piezoelectric transducers that convert electrical signals into mechanical vibrations in the delay line medium. This non-mechanical approach removes the problems of mechanical misalignment, incorrect settings, and beam divergence, while maintaining precise control over the time interval through electrical signal control.
3Measurement precision
If the ASOPS technique is used with two light sources having repeat frequencies of at least one gigahertz, then sufficient time resolution can be achieved, but the scanning range becomes much too large for most practical applications
Solution Approach 1:
The patent changes the controlling parameter from high repeat frequency (gigahertz range in ASOPS) to acoustic wave frequency (megahertz range). By using acoustic waves to modulate the optical path length in a single laser system, the patent achieves fine time resolution (controllable to a few 10 ps) while limiting the scanning range to practically useful values. The acoustic wave frequency and amplitude can be precisely controlled to achieve the desired balance between resolution and range.
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 allows for precise control of time offsets down to a few 10 ps, optimizing scanning ranges and ensuring useful measurement data throughout the measurement time, reducing the need for mechanical adjustments and expensive laser systems.
Implementation Method 1
forming a regulation signal within a regulation circuit from a cycle signal and the light pulse sequence of the light source, via a phase detector
Implementation Method 2
The regulation circuit includes a regulator that generates a setting signal that influences the repeat frequency of the light pulse sequence of the light source
Data Source
AI summary
A device for generating light pulses that are separated in terms of time has a light source that emits a sequence of light pulses. A regulation signal is formed within a regulation circuit from a cycle signal and the light pulse sequence of the light sources via a phase detector. The regulation circuit includes a regulator that generates a setting signal that influences the repeat frequency of the light pulse sequence of the light source.