Acousto-Optic Deflector Scanning Trajectory Control
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Solution Overview
Problem
Conventional acousto-optic scanners face limitations in scanning speed due to mechanical inertia and experience spot spreading during switching times in RAMP mode, preventing continuous measurement along arbitrary trajectories.
Innovation Solution
By varying the frequency slopes of acousto-optic deflectors in the x-z and y-z planes over time, allowing continuous movement of the focal spot along arbitrary trajectories without the need for discrete frequency changes, thus eliminating switching times and maintaining spot integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If mechanical scanning components (scanning mirrors and microscope objective) are used to move the focus spot, then the system can perform 3D scanning, but the scanning speed is limited due to mechanical inertia
Solution Approach 1:
The patent replaces mechanical scanning components (galvanometric mirrors and piezo-positioners) with an acousto-optic scanning system that uses acoustic waves to deflect and focus the laser beam. The acousto-optic deflectors use sound waves propagating through an acousto-optic medium to change the refractive index, thereby steering the beam without any moving mechanical parts, eliminating inertia-related speed limitations
Solution Approach 2:
The patent employs dynamic control of acoustic frequency to achieve rapid beam deflection and focal plane changes. By continuously varying the acoustic frequency in the acousto-optic deflectors, the system can dynamically reposition the focal spot at high speeds without mechanical acceleration constraints, enabling scanning speeds limited only by acoustic wave propagation
2Ease of operation
If discrete frequency changes are used in RAMP mode to address different points, then random access scanning is achieved, but spot spreading occurs during switching times preventing continuous measurement
Solution Approach 1:
The patent implements continuous frequency sweeping instead of discrete frequency jumps between points. The acoustic frequency is continuously varied to move the focal spot along a continuous trajectory, eliminating the switching gaps and spot spreading that occur in discrete RAMP mode. This continuous action ensures the focal spot remains intact and measurements can be performed without interruption along the scanning path
Solution Approach 2:
The patent pre-calculates and applies the appropriate frequency sweep profile before scanning begins, ensuring the focal spot is continuously positioned along the desired trajectory. The acoustic frequency is modulated in advance according to the required scanning path, allowing the system to maintain spot integrity throughout the measurement process without discrete repositioning events
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
Enables faster and more precise 2D and 3D scanning by maintaining spot integrity and reducing astigmatism, allowing continuous scanning without the need for discrete point jumping, thereby enhancing scanning speed and accuracy.
Implementation Method 1
a first pair of acousto-optic deflectors for deflecting a focal spot of an electromagnetic beam traversing a consecutive lens system defining an optical axis (z) in an x-z plane, and a second pair of acousto-optic deflectors for deflecting the focal spot in a y-z plane
Implementation Method 2
traversing a consecutive lens system defining an optical axis (z)
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a method for scanning along a continuous scanning trajectory with a scanner system (100) comprising a first pair of acousto-optic deflectors (10) for deflecting a focal spot of an electromagnetic beam generated by a consecutive lens system (200) defining an optical axis (z) in an x-z plane, and a second pair of acousto-optic deflectors (20) for deflecting the focal spot in a y-z plane being substantially perpendicular to the x-z plane, characterised by changing the acoustic frequency sweeps with time continuously in the deflectors (12, 12') of the first pair of deflectors (10) and in the deflectors (22, 22') of the second pair of deflectors (20) so as to cause the focal spot to move continuously along the scanning trajectory.