Sample Stage Drift Compensation Across Orthogonal Axes
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Solution Overview
Problem
Sample stages in scanning electron microscopes and similar instruments suffer from drift due to flexure of mechanical parts, backlash, and stress from lubricant viscous resistance, which affect precise sample positioning.
Innovation Solution
A sample stage with a first drive mechanism for displacing a sample support base relative to a first axis and a second drive mechanism for reducing drift relative to a second axis, controlled by a controller that performs complementary operations to mitigate drift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single drive mechanism is used to displace the sample support base, then the device complexity is reduced, but drift occurs in directions perpendicular to the movement direction due to mechanical flexure and backlash
Solution Approach 1:
The second drive mechanism is designed to serve dual purposes: its primary function is to displace the sample support base along the second axis, and its secondary function is to counteract drift in the second axis direction caused by operations of the first drive mechanism. This multi-functionality allows the system to maintain positioning precision without adding excessive complexity, as the second drive mechanism's drift compensation capability is leveraged to resolve the positioning error caused by the first drive mechanism's mechanical flexure and backlash.
2Manufacturing precision
If the second drive mechanism performs drift compensation operations, then positioning precision is improved, but the duration of action increases due to additional corrective movements
Solution Approach 1:
The controller is configured to perform drift compensation operations of the second drive mechanism in conjunction with the primary displacement operation of the first drive mechanism. By integrating the drift compensation into the same operational timeframe rather than performing it as a separate subsequent action, the system achieves positioning precision improvement without proportionally increasing the total operation time. The preliminary planning and coordinated execution of both drive mechanisms' operations allows drift correction to occur during the main positioning maneuver.
Data Source
AI summary
There is provided an observation instrument capable of reducing drift of a sample. The observation instrument is used for observation of the sample and includes a sample stage and a controller for controlling the sample stage. The sample stage has a sample support base on which the sample is placed, a first drive mechanism for displacing the sample support base relative to a first axis, and a second drive mechanism for displacing the sample support base relative to a second axis different from the first axis. If the first drive mechanism is caused to perform a first operation for displacing the sample support base relative to the first axis, the controller causes the second drive mechanism to perform a second operation for reducing such drift of the sample support base relative to the second axis that is concomitant with the first operation.