Surface Inspection Sample Positioning for Shallow Focal Ranges
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Solution Overview
Problem
Existing surface inspection devices struggle to accurately drive samples in the focus direction due to variations in sample height, leading to potential deviations from the optical system's focal range, especially when the sample surface is not perpendicular to the focus direction, affecting detection sensitivity and accuracy.
Innovation Solution
A surface inspection device with a sample holding member, spindle motor, turntable, and support members that allow precise displacement in the focus direction, using magnets and coils to stabilize the sample position, ensuring it remains within the optical system's focal range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the wavelength of laser light is shortened to improve detection sensitivity, then detection sensitivity is improved, but depth of focus becomes shallow causing the sample surface to go out of focal range
Solution Approach 1:
The patent applies dynamics by making the sample holding member movable in the focus direction through support members that enable displacement. This allows the system to dynamically adjust the sample position to maintain it within the shallow focal range of the optical system when using short-wavelength laser light, thereby preserving both detection sensitivity and focal range requirements.
2Manufacturing precision
If the sample is driven in the vertical direction to maintain focus, then the sample position can be adjusted, but accurate driving in the focus direction is difficult when the sample surface is sloped
Solution Approach 1:
The patent segments the support function by providing multiple support members (at least two) that independently support the sample holding member. This segmentation allows differential adjustment of support forces to counteract sloping effects, enabling accurate vertical positioning even when the sample surface is not perfectly perpendicular to the focus direction.
Solution Approach 2:
The patent implements feedback through detection means that detect the position of the sample in the focus direction, and this detection information is fed back to control the drive means. This closed-loop feedback system continuously corrects the sample position to maintain accuracy despite surface slope variations.
3Stability of the object's composition
If multiple support members are used to support the sample holding member, then the sample can be stabilized, but the complexity of the device increases
Solution Approach 1:
The support members serve multiple functions: they mechanically support the sample holding member, enable vertical displacement in the focus direction, and work in conjunction with detection and drive means to maintain sample positioning accuracy. This multi-functionality reduces the need for separate systems and mitigates the increase in device complexity.
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 device enables accurate and high-speed sample driving in the focus direction, maintaining the sample within the optical system's focal range, thereby enhancing detection sensitivity and inspection accuracy.
Implementation Method 1
a stator including a coil for driving the stage in the Z direction
Data Source
AI summary
A surface inspection device (1) according to the present invention comprises: a plate-shaped sample holding member (3) which can hold a sample (2); a spindle motor (4) for rotating the sample holding member (3); a turntable (5) which is fixed to the spindle motor (4) and rotated by the spindle motor (4); a frame (6) to which the spindle motor (4) is fixed; a plurality of support members (12) each having one end fixed to the sample holding member (3) and the other end fixed to the turntable (5), the support members supporting the sample holding member (3) such that the sample holding member is displaceable in a focus direction which is the height direction with respect to the turntable (5); and a sample drive unit (11) which displaces the sample holding member (3) in the focus direction with respect to the turntable (5). This surface inspection device (1) can accurately drive the sample (2) in the focus direction.