Charged-Particle Diffractometer Sample Stage for On-Axis Tilt Alignment
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Solution Overview
Problem
Existing charged-particle diffractometers face challenges in stabilizing the positioning of small samples relative to the charged-particle beam, particularly requiring laborious and time-consuming repositioning due to gravitational and manufacturing-induced deviations of the rotation axis, especially when dealing with nano-crystalline samples.
Innovation Solution
A charged-particle irradiation unit with a manipulator system that includes a rotation stage with a vertical axis, coupled with translation stages to compensate for gravitational and manufacturing-induced deviations, ensuring the sample remains on-axis and stable during rotational positioning, allowing for automatic alignment and continuous tilting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the sample is mounted off-center with respect to the rotation axis, then the sample can be positioned within the beam, but the sample volume is displaced from the beam axis when changing tilt angles, requiring laborious repositioning
Solution Approach 1:
The sample center is pre-aligned with the rotation axis using the first translation stage before tilting begins. This preliminary positioning ensures that the sample remains on-axis throughout the tilt series, eliminating the need for repeated repositioning operations during data collection.
Solution Approach 2:
The patent replaces manual mechanical repositioning with an automated manipulator system that includes translation stages and a rotation stage. This automated system can quickly and precisely adjust sample position and orientation, substituting laborious manual operations with automated control.
2Measurement precision
If manual repositioning is performed for each tilt angle, then sample alignment can be maintained, but the process becomes laborious and time-consuming
Solution Approach 1:
The patent replaces manual mechanical repositioning with an automated manipulator system controlled by a computer. This system uses motorized translation stages and a rotation stage to automatically maintain sample alignment throughout the tilt series, eliminating manual intervention while preserving alignment precision.
Solution Approach 2:
The manipulator system is designed to automatically compensate for position changes during tilting without requiring external manual adjustment. The system self-corrects sample positioning through coordinated movement of the translation stages and rotation stage, maintaining alignment precision while enabling continuous data acquisition.
3Device complexity
If a horizontal rotation axis is used, then the manipulator structure can be simpler, but gravitational effects cause the rotation axis position to vary between different rotational positions
Solution Approach 1:
The patent uses a vertical rotation axis orientation, which creates equipotential conditions for gravitational effects. By orienting the rotation axis vertically, all components at the same radial distance from the axis experience equal gravitational potential, eliminating gravitational-induced position variations that would occur with a horizontal axis.
4Ease of manufacture
If the rotation axis deviates from the nominal reference position due to manufacturing tolerances, then the device can be manufactured more easily, but sample positioning accuracy deteriorates
Solution Approach 1:
The patent incorporates feedback mechanisms through the coordinated control of multiple translation stages and a rotation stage. The system continuously monitors and adjusts sample position to compensate for manufacturing deviations in the rotation axis, using feedback from position sensors to maintain accurate sample positioning despite manufacturing tolerances.
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
The solution provides stable and efficient sample positioning, reducing the need for re-alignment and enabling continuous data acquisition with improved accuracy and reduced time, suitable for cryogenic conditions and nano-crystalline samples.
Implementation Method 1
a charged-particle source for generating a charged-particle beam along a charged-particle beam axis
Implementation Method 2
a charged-particle-optical system for manipulating the charged-particle beam such as to irradiate the sample with the charged-particle beam
Data Source
AI summary
A charged-particle irradiation unit and a diffractometer comprising such an irradiation unit, wherein the irradiation unit comprises a charged-particle source, a charged-particle-optical system, a sample holder and a manipulator operatively coupled to the sample holder for positioning a sample relative to the beam axis. The manipulator comprises a rotation stage for rotating the sample holder with respect to the incident beam around a substantially vertical rotation axis, a first translation stage configured to move the sample holder at least along a first sample axis and a second sample axis in a plane perpendicular to the rotation axis, and a second translation stage configured to move the rotation stage, the sample holder and the first translation stage at least along a first manipulator axis that is perpendicular to the beam axis and perpendicular to the vertical direction. The rotation stage is in a moving system of the second translation stage, the first translation stage is in a rotational system of the rotation stage, and the sample holder is in a moving system of the first translation stage. Thus, the manipulator can position the center of mass of the sample substantially on-axis with regard to the rotation axis and to compensate for different rotational positions of the rotation stage a respective measured or pre-determined native deviation of the rotation axis from a position of a nominal reference rotation axis of the rotation stage at least in a direction that is perpendicular to the beam axis and perpendicular to the vertical direction.