ATR Force Control via Z-Axis Stage and Load Cell
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Solution Overview
Problem
Conventional Attenuated Total Reflectance (ATR) measurement systems face challenges in maintaining consistent contact pressure during successive scans, leading to sample deformation and degradation, which affects measurement accuracy.
Innovation Solution
A firmware-controlled z-axis stage and sensitive load cell or strain gauge are used to maintain contact pressure between the ATR tip and the sample by adjusting the z-axis stage between scans, ensuring consistent force application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional mechanical pressure mechanisms (screws, levers, slides, actuators) are used to apply compressive forces on the sample, then contact pressure is applied to enable efficient optical coupling, but the samples deform resulting in degradation in measurements over successive scans
Solution Approach 1:
The patent replaces conventional mechanical pressure mechanisms (screws, levers, slides) with an automated motorized z-axis stage system. The stage is controlled by firmware to precisely position the ATR crystal relative to the sample, applying consistent contact pressure without the sample deformation caused by manual mechanical mechanisms. The system uses automated positioning rather than continuous mechanical compression.
Solution Approach 2:
The system automatically monitors and maintains contact pressure between scans using a load cell sensor and feedback control. The firmware-controlled stage self-adjusts the z-axis position to maintain optimal contact force, eliminating the need for manual intervention and preventing sample degradation through consistent, automated pressure maintenance.
2Reliability
If manual mechanical mechanisms are used to apply force, then contact is established between ATR crystal and sample, but contact pressure is not maintained consistently over successive scans
Solution Approach 1:
The patent incorporates a load cell sensor that continuously monitors the contact force between the ATR crystal and sample. This feedback is processed by firmware-controlled logic that automatically adjusts the z-axis stage position to maintain consistent contact pressure. The closed-loop feedback system ensures reliable pressure maintenance without manual intervention.
Solution Approach 2:
The system dynamically adjusts the z-axis position parameter between scans to maintain optimal contact pressure. The firmware modifies the stage position coordinate based on load cell feedback, changing this physical parameter to compensate for any drift or sample deformation, thereby maintaining consistent measurement conditions.
3Measurement precision
If conventional stages are used without automated control, then device complexity is lower, but measurement precision degrades over successive scans due to sample deformation
Solution Approach 1:
The patent replaces simple mechanical stages with a motorized z-axis stage system controlled by firmware. This substitution adds electronic control components but eliminates sample deformation, thereby improving measurement precision. The automated positioning system maintains consistent optical coupling conditions across multiple scans, overcoming the limitations of conventional mechanical stages.
Solution Approach 2:
The firmware-controlled stage system acts as an intermediary between the operator and the sample, automatically managing contact pressure and positioning. This intermediary layer adds complexity but protects the sample from direct manual manipulation, ensuring consistent measurement conditions and improved spectral accuracy over successive scans.
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 approach improves sample testing and identification by maintaining consistent contact pressure, reducing measurement degradation and enhancing data accuracy over multiple scans.
Implementation Method 1
A firmware-controlled z-axis stage and sensitive load cell (and/or strain gauge) to maintain contact pressure between an ATR tip and the sample
Implementation Method 2
In operation, a beam of light (e.g., infrared (IR)) is passed through an IRE crystal (or ATR crystal) in such a way that it reflects at least once off of the internal surface in contact with a sample
Implementation Method 3
ATR capitalizes on total internal reflected light produced at the interface of a configured internally reflecting element (IRE) and a coupled sample plane
Data Source
AI summary
A measurement system configured to examine a sample. The system comprises an internally reflective element, a contact member, an actuator, an optical assembly, a sensor, and a controller. The contact member and the reflective element are configured to apply a force to the sample. The optical assembly is configured to scan the sample. Whereby prior to the scan, an initial force is applied to the sample, and after the scan, a resulting force is applied to the sample. The sensor is configured to detect the resulting force applied to the sample, and the controller is configured to receive a signal from the sensor indicative of the detected resulting force. The controller is further configured to control the actuator to adjust the force applied to the sample by the contact member and the internally reflective element from the resulting force to the initial force.