Laser Scanning Microscope 3D Trajectory Control
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Solution Overview
Problem
Current 3D laser scanning microscopes face deviations from desired scan trajectories due to mechanical component inertia, particularly at higher frequencies, leading to inefficiencies in focusing and potential missed points of interest when scanning specimens like nerve cells, where rapid Z-axis movement is necessary.
Innovation Solution
A control system that generates periodical drive signals for the piezo-positioner and deflecting means, allowing for stable response function calculation and compensation for shape distortions, enabling scanning at frequencies up to 200 Hz with precise 3D trajectory maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the frequency of the sinusoidal drive signal is increased to reduce scan time, then productivity is improved, but the deviation from the desired scan trajectory increases due to mechanical component inertia
Solution Approach 1:
The system pre-calculates a corrected XY drive signal that anticipates the Z-axis positioning delays and trajectory deviations. By computing the necessary XY compensation in advance based on the desired 3D trajectory and measured Z-response characteristics, the system ensures the focal spot arrives at the correct position despite mechanical inertia, allowing higher scan frequencies without sacrificing accuracy
Solution Approach 2:
The system measures the actual Z-position response to the sinusoidal drive signal and uses this feedback to calculate a corrected XY drive signal. The measurement of the Z-response function and its use to compute trajectory compensation creates a closed-loop system that adapts to the actual mechanical behavior, enabling accurate scanning at higher frequencies
2Loss of time
If the frequency of the sinusoidal drive signal is increased to reduce scan time, then loss of time is reduced, but measurement precision deteriorates due to focus positioning errors
Solution Approach 1:
The system pre-calculates the XY compensation signal based on the desired 3D trajectory and the measured Z-response function before scanning begins. This preliminary calculation allows the system to operate at higher frequencies while maintaining focus positioning accuracy, as the compensation is already built into the drive signal
Solution Approach 2:
The system uses measured Z-position data to compute a corrected XY drive signal that compensates for positioning errors. This feedback mechanism ensures that even at higher scan frequencies, the focal spot remains accurately positioned on the specimen, preserving measurement precision
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 fast and accurate 3D scanning by compensating for mechanical deviations, allowing for rapid movement and precise focusing across a range of frequencies without compromising XY resolution, thus reducing overall scan time and improving data acquisition efficiency.
Implementation Method 1
drive means for displacing the at least one optical element of the focusing means for changing the position of the focal plane
Implementation Method 2
deflecting means for deflecting the laser beam
Implementation Method 3
Two-photon laser scanning microscopes use a laser light of lower energy of which two photons are needed to excite a flourophore in a quantum event, resulting in the emission of a fluorescence photon
Data Source
Figure 1
Figure 1a~3c
Figure 2
AI summary
The invention relates to a laser scanning microscope (10) having: focusing means (15) having a focal plane (29) and comprising at least one optical element for focusing a laser beam (13); drive means (18) for displacing the at least one optical element of the focusing means (15) for changing the position of the focal plane (29), and deflecting means (14) for deflecting the laser beam (13). The microscope comprises a control system (32) configured to carry out the steps of: providing a periodical drive signal for the drive means (18); obtaining time dependant displacement data of the at least one optical element of the focusing means (15) in response to the periodical drive signal of the drive means (18); providing a response function (z(t)) using the time dependant displacement data, calculating a drive signal for the deflecting means (14) using the response function (z(t)) to move the focal volume (30) of the laser beam (13) along a given 3D trajectory (48) within a sample to be examined. The invention further relates to a method for carrying out such a scanning operation along a 3D trajectory (48). ?