Gas-Tight Sample Cell Holder with Angled Windows for Vacuum Spectroscopy
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Solution Overview
Problem
Existing infrared-based bio-fluid studies face limitations due to low sensitivity, water absorption, and interference effects, particularly in field-resolved spectroscopy, which are exacerbated by the need for vacuum-compatible sample cells that are difficult to integrate and adjust in laboratory settings.
Innovation Solution
A sample receptacle apparatus with a sample cell and cell holder device that allows for gas-tight integration into a vacuum environment, reduces interference effects by angling cell windows relative to the beam path, and uses diamond windows for minimal dispersion, enabling improved signal-to-noise ratio and ease of adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the thickness of the sample cell is reduced to a few μm to overcome water absorption, then the spectroscopic sensitivity is improved, but the sample cell easily clogs, especially for biological samples containing large proteins
Solution Approach 1:
The sample cell is divided into two separate cells with different thicknesses arranged in series. The first cell has a small thickness (a few μm) for high spectroscopic sensitivity, while the second cell has a larger thickness for reliable sample flow and reduced clogging. This segmentation allows each cell to fulfill its specific function optimally.
Solution Approach 2:
Instead of using a single thin cell, the solution transitions to a multi-cell arrangement in series, adding a dimensional aspect to the sample path. This allows the system to achieve both high sensitivity (through the first thin cell) and reliability (through the second thicker cell that prevents clogging).
2Ease of operation
If the sample cell is placed with cuvette walls perpendicular to the incident laser beam, then the setup is simple, but back-reflection reaches the detector and impairs the detector signal
Solution Approach 1:
The sample cell is rotated by 45 degrees relative to the incident laser beam, changing from a symmetric perpendicular arrangement to an asymmetric angled arrangement. This asymmetry causes back-reflection to be directed away from the detector path, eliminating signal impairment while maintaining operational simplicity through the standardized 45-degree mounting configuration.
Solution Approach 2:
The back-reflection that would normally harm the measurement is redirected to serve a useful purpose by being directed away from the detector. The 45-degree angle converts the harmful back-reflection into a beneficial configuration where the reflection is separated from the transmitted beam path, improving detector signal quality.
3Measurement precision
If vacuum-compatible sample cells are used in an evacuated measuring apparatus, then interference effects are reduced, but the sample cells are difficult to integrate and adjust in laboratory settings
Solution Approach 1:
The vacuum system is segmented into separate chambers: a vacuum chamber containing the measurement optics and a separate sample loading chamber. The sample cell can be loaded and prepared at atmospheric pressure, then the entire assembly is transferred to or integrated with the vacuum chamber, simplifying integration while maintaining vacuum compatibility and measurement precision.
Solution Approach 2:
A vacuum-compatible holder or mounting mechanism serves as an intermediary between the atmospheric sample cell and the vacuum measurement system. This intermediary component allows easy integration and adjustment of the sample cell while maintaining the vacuum seal, bridging the gap between laboratory ease of use and vacuum environment requirements.
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
Facilitates high-sensitivity spectroscopic measurements with reduced interference and adjustment efforts, allowing for efficient integration of sample cells into vacuum systems and improved transmission of measuring radiation.
Implementation Method 1
reduces interference effects by angling cell windows relative to the beam path
Implementation Method 2
reduces interference effects by angling cell windows relative to the beam path
Implementation Method 3
uses diamond windows for minimal dispersion
Implementation Method 4
water is a strong absorber in the mid-infrared (MIR) wavelength range
Data Source
Figure 1~2
Figure 3~4
Figure 5~8
AI summary
A sample receptacle apparatus (100) for arranging a fluid sample (1) in a beam path (2) of measuring radiation (3) in a gas-tight measuring apparatus (200), comprises a sample cell (10) having plane, plate-shaped cell windows (11) with a spacing therebetween, wherein the sample cell (10) is configured for accommodating the sample (1) in the spacing between the cell windows (11), and a cell holder device (20) having a cell support body (21), a first coupling section (22) and a second coupling section (23), wherein the cell support body (21) is configured for accommodating the sample cell (10) and for setting a temperature of the sample cell (10), the first and second coupling sections (22), (23) are configured for a gas-tight coupling of the cell holder device (20) with a closed container device (240) of the measuring apparatus (200), and the cell holder device (20) provides a beam passage (4) along a longitudinal direction z through the first coupling section (22), the cell support body (21) with the sample cell (10), and the second coupling section (23), wherein the sample cell (10) is arranged in the beam passage (4) such that a normal of at least one of the cell windows (11) deviates from the longitudinal direction (z) of the beam passage (4). Furthermore, a measuring apparatus for a spectroscopic investigation of a sample, including the sample receptacle apparatus (100) and a spectroscopic measuring method are described.