Total Reflection Measurement Device with Inverted Concave Sub-Mirror
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Solution Overview
Problem
Conventional Cassegrain type objective mirrors have poor light utilization rates for both measurement and total reflection light, leading to inefficient measurement and a limited target region in mapping measurements, while maintaining high magnification results in a compact but restricted measurement area.
Innovation Solution
A total reflection measurement device using a pair of plane mirrors and ellipsoidal mirrors with intermediate mirrors to improve light utilization, allowing for lower magnification and maintaining device compactness, while using a retractable ATR crystal for switching between total reflection and reflection measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a Cassegrain type objective mirror with a convex sub-mirror is used, then the device can be made compact with high magnification, but the light utilization rate for both measurement light and total reflection light becomes poor
Solution Approach 1:
The patent inverts the conventional Cassegrain mirror configuration by replacing the convex sub-mirror with a concave sub-mirror. This inversion allows the sub-mirror to effectively reflect and focus both measurement light and total reflection light, resolving the light utilization problem while maintaining the compact high-magnification design.
Solution Approach 2:
The patent changes the curvature parameter of the sub-mirror from convex to concave, fundamentally altering the optical path and focusing characteristics. This parameter change enables the sub-mirror to contribute positively to light collection and focusing, improving light utilization rate while preserving device compactness.
2Device complexity
If the sub-mirror of the Cassegrain mirror is used for measurement light, then the device structure is simplified, but the measurement light passes through the central hole and escapes without being incident to the concave surface of the main mirror
Solution Approach 1:
By inverting the sub-mirror from convex to concave, the patent creates an optical path where measurement light is properly directed to the main mirror's concave surface through the sub-mirror, preventing light escape through the central hole while maintaining structural simplicity.
3Volume of moving object
If high magnification is maintained in the objective mirror, then the device remains compact, but the target region for mapping measurement is narrowed
Solution Approach 1:
The patent introduces a retractable ATR crystal that can dynamically adjust its position between the objective mirror and the sample. This dynamic adjustment capability allows the system to switch between high-magnification point measurement and low-magnification mapping measurement, expanding the measurable target region while maintaining device compactness.
4Reliability
If the ATR crystal is fixed in position, then the total reflection measurement can be performed, but mapping measurement requires relative movement between the ATR crystal and sample
Solution Approach 1:
The patent implements a retractable ATR crystal mechanism that can be dynamically extended or retracted. For total reflection measurement, the crystal is extended to contact the sample, ensuring stable measurement. For mapping measurement, the crystal can be retracted, eliminating the need for complex relative movement mechanisms and simplifying 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
Enhances measurement accuracy and increases the measurement region by improving light utilization and maintaining device size compatibility with high magnification objective mirrors, enabling efficient low-magnification total reflection and reflection measurements.
Implementation Method 1
an ellipsoidal mirror on a measurement light side provided at a position opposing to the intermediate mirror on the measurement light side as an objective mirror on the measurement light side
Implementation Method 2
Attenuated total reflection measurement (also referred to as ATR) method is a method for measuring absorption property of a sample by bringing a crystal (prism) having larger refractive index than the sample into contact with the sample
Data Source
AI summary
To provide a total reflection measurement device that can improve a light utilization rate more than a Cassegrain type objective mirror, is capable of total reflection measurement at low magnification, and can maintain compatibility with a conventional objective mirror. The device (1) includes: a pair of plane mirrors (2a, 2b) disposed on a central axis (P1); a pair of intermediate mirrors (4a, 4b) opposing to the plane mirrors (2a, 2b), respectively; a pair of ellipsoidal mirrors (6a, 6b) opposing to the intermediate mirrors (4a, 4b), respectively; and an ATR crystal (8) provided at a position nearer to the sample side than the pair of plane mirrors (2a, 2b) on the central axis (P1). The ellipsoidal mirrors (6a, 6b) are provided so that each one focal position (C1) formed by the intermediate mirror (4a, 4b) and the plane mirror (2a, 2b) are at same position on the central axis (P1), and each another focal position (C2) formed by only the intermediate mirror (4a, 4b) are also at same position on the central axis (P1). Further, the another focal position (C2) coincides with a boundary surface between the ATR crystal (8) and the sample.