Electron Diffractometer Sample Stage for Tilt-Centered Positioning
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Solution Overview
Problem
Existing electron diffraction techniques for small crystalline samples require laborious and time-consuming repositioning of the sample relative to the charged-particle beam due to displacement when changing tilt angles, especially when the sample is off-center.
Innovation Solution
A diffractometer with a multi-axes translation stage operatively coupled between the sample holder and rotation stage, allowing precise on-axis positioning of the sample's center of mass, minimizing re-alignment needs by maintaining the sample within the beam for varying tilt angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the sample is positioned off-center with respect to the tilt axis, then the sample can be mounted on the sample holder, but the sample volume is removed from the beam axis when changing tilt angles, requiring laborious and time-consuming repositioning
Solution Approach 1:
The multi-axes translation stage is configured to perform preliminary positioning of the sample's center of mass onto the tilt axis before tilt angle changes occur. This advance positioning ensures the sample remains centered during subsequent tilting operations, eliminating the need for time-consuming repositioning between measurements.
Solution Approach 2:
The multi-axes translation stage acts as an intermediary device between the sample holder and the rotation stage. It provides an additional degree of freedom for sample positioning, mediating the relationship between the fixed tilt axis and the movable sample, thereby enabling precise centering independent of the tilt mechanism.
2Measurement precision
If the sample is positioned off-center with respect to the tilt axis, then the sample can be mounted on the sample holder, but repositioning of the sample is required for each image of the tilt series
Solution Approach 1:
The manipulator is segmented into distinct functional components: the rotation stage for tilt angle control and the multi-axes translation stage for positional control. This segmentation allows each component to perform its specialized function independently, with the translation stage handling precise positioning and the rotation stage handling angular orientation.
Solution Approach 2:
The multi-axes translation stage serves multiple functions: it positions the sample's center of mass onto the tilt axis, maintains sample centering during tilt angle changes, and enables precise positioning for each image in the tilt series. This multi-functionality reduces the need for additional specialized devices.
3Productivity
If the sample is positioned off-center with respect to the tilt axis, then the sample can be mounted on the sample holder, but the procedure becomes laborious and time-consuming
Solution Approach 1:
The system incorporates feedback mechanisms that monitor the sample's position relative to the beam axis during tilt angle changes. This feedback information is used to automatically adjust the sample position via the multi-axes translation stage, maintaining optimal positioning without requiring manual intervention and thereby improving both productivity and ease of operation.
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 stable and efficient data acquisition with reduced repositioning requirements, enhancing positional accuracy and reducing data collection time by keeping the sample centered within the beam throughout tilt angle changes.
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
Implementation Method 3
a charged-particle detection system at least for collecting a diffraction pattern of the sample based on the beam of charged-particles transmitted through the sample
Data Source
AI summary
The present invention relates to a diffractometer for charged-particle crystallography of a crystalline sample, in particular for electron crystallography of a crystalline sample. The diffractometer comprises a charged-particle source for generating a charged-particle beam along a charged-particle beam axis, a charged-particle-optical system for manipulating the charged-particle beam such as to irradiate the sample with the charged-particle beam and a charged-particle detection system at least for collecting a diffraction pattern of the sample based on the beam of charged-particles transmitted through the sample. The diffractometer further comprises a sample holder for holding the sample and a manipulator operatively coupled to the sample holder for positioning the sample relative to the beam axis. The manipulator comprises a rotation stage for tilting the sample holder with respect to the incident charged-particle beam around a tilt axis, and a multi-axes translation stage for moving the sample holder at least in a plane perpendicular to the tilt axis. The multi-axes translation stage is operatively coupled between the sample holder and the rotation stage such that the multi-axes translation stage is in a rotational system of the rotation stage and the sample holder is in a moving system of the multi-axes translation stage.