Oblique Camera Positioning for Ellipsometer Sample Viewing
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Solution Overview
Problem
Conventional systems for investigating samples with electromagnetic beams face limitations when the camera is positioned offset from the sample, leading to restricted motion of the source and detector, and an inability to achieve focused images over the entire sample surface, especially at small angles of incidence.
Innovation Solution
The camera is positioned at an oblique angle relative to the sample surface, meeting the Scheimpflug condition by orienting the camera sensor plate, focusing means, and sample stage such that the tangent of the camera's viewpoint angle equals the distance from the camera to the focusing means' center minus the focal length, times the tangent of the angle of incidence, allowing for a focused view of the sample surface without interfering with the source and detector motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the camera is positioned offset from the sample along a perpendicular to the surface, then the image provided by the camera is in focus over the full area of the sample, but the source and detector motion is further limited than otherwise is the case
Solution Approach 1:
The camera is repositioned from the conventional perpendicular offset position to a location along the arm extending from the sample to the detector. This dimensional relocation allows the camera to view the sample without interfering with the vertical motion of the source and detector, thereby resolving the contradiction between maintaining image focus quality and preserving motion range.
Solution Approach 2:
The arm structure serving the detector acts as an intermediary carrier for mounting the camera. This intermediary positioning allows the camera to be integrated into the existing system architecture without compromising the functional independence and motion capabilities of the source and detector components.
2Measurement precision
If the angles of incidence and angle of reflection both approach 0 degrees, then the measurement configuration is optimized, but physical aspects of the effective arms, source and detector can limit motion
Solution Approach 1:
The camera is positioned in the horizontal plane along the detector arm rather than offset in the vertical dimension. This spatial reconfiguration allows the system to achieve small angles of incidence and reflection for precise measurements while maintaining the vertical motion freedom of the source and detector.
3Ease of operation
If the camera is positioned at an offset from the sample, then the camera can view the sample surface, but the source and detector motion is restricted
Solution Approach 1:
The camera is relocated from a conventional perpendicular offset position to a position along the horizontal arm extending from the sample to the detector. This dimensional change allows the camera to maintain its sample viewing capability while eliminating interference with the vertical motion of the source and detector, thereby preserving system adaptability.
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
This configuration enables a focused optical view of the sample surface over its entire extent, even at small angles of incidence, without physically restricting the motion of the source and detector, thereby overcoming the limitations of conventional setups.
Implementation Method 1
positioning a camera sensor plate and focusing means such that the Scheimpflug condition is met thereby providing an in-focus view of the entire surface of the sample
Implementation Method 2
a source of a beam of electromagnetic radiation; a stage for supporting a sample; a detector... such that when the angle of incidence of a beam onto a sample is set at θ with respect to a perpendicular to the sample surface, the detector is also set at an angle θ, (reflected through the perpendicular locus), so that a beam reflecting from the sample enters thereinto
Data Source
AI summary
In the context of an ellipsometer or the like, positioning a camera other than directly above a sample being investigated by an electromagnetic beam, while said camera provides an optical view of a surface of said sample which is in focus over the entire viewed extent of the sample, and wherein a contrast improving system involving two beams provided by a beam splitting system is utilized.