Optical Displacement Sensor for High-Pressure Material Volume Measurement
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Solution Overview
Problem
Conventional test cells for measuring volumetric expansion and contraction of materials under high-pressure, high-temperature conditions rely on linear variable differential transformers (LVDTs), which are limited by the need for a physically attached magnetic core, suffer from external electromagnetic interference, and have restricted range and precision.
Innovation Solution
A displacement measurement device using a cell body, a translating member with a reflective surface, a directed electromagnetic signal generator, and a sensor system that employs a lens to transmit and receive electromagnetic signals, allowing for frictionless measurement of material expansion and contraction through axial linear movement within a controlled high-pressure, high-temperature environment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a linear variable differential transformer (LVDT) is used to measure volumetric change, then the measurement can be performed in a high-pressure, high-temperature environment, but the magnetic core must be physically attached to the moving component and the magnetic coil must slide freely without contact, which constrains test cell configuration and reduces reliability
Solution Approach 1:
The patent replaces the mechanical LVDT system with an optical measurement system using a laser displacement sensor. The laser beam transmits through the pressurizing media and reflects off the translating member's reflective surface, eliminating the need for physical attachment of magnetic components to moving parts and removing contact friction constraints.
Solution Approach 2:
The patent introduces a reflective surface on the translating member as an intermediary to enable optical measurement. The laser beam interacts with this reflective surface to measure displacement, serving as a mediator that allows non-contact measurement in the high-pressure environment without requiring direct attachment of sensors to moving components.
2Measurement precision
If an LVDT sensor is used, then volumetric change can be measured, but the sensor is affected by external electromagnetic disturbances and has limited range and precision
Solution Approach 1:
The patent substitutes the electromagnetic LVDT sensor with an optical laser displacement sensor. This replacement eliminates sensitivity to external electromagnetic disturbances while providing extended measurement range and higher precision through non-contact optical detection of the translating member's displacement.
3Ease of operation
If a magnetic core is physically attached to the translating member, then the LVDT can measure displacement, but the magnetic coil must slide freely inside the test cell without contact, which creates constraints on test cell design and operation
Solution Approach 1:
The patent replaces the mechanical sliding coil system with a stationary optical sensor system. The laser displacement sensor remains stationary outside the pressurized chamber, transmitting beams through the transparent or translucent cell walls, thereby eliminating the need for sliding magnetic coils and providing full design flexibility for test cell configurations.
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 solution provides precise and interference-free measurement of material volume changes, overcoming the limitations of LVDTs by using a CCD laser displacement sensor for accurate tracking of linear displacement and volume variations under extreme conditions.
Implementation Method 1
a lens allowing transmission of a generated signal and a reflected signal
Implementation Method 2
encounter the translating member reflective surface and be reflected through the lens to the sensor
Data Source
AI summary
A test cell for determining expansion or contraction of a sample contained therein includes, a test cell body, a reflective surface within the test cell body, the reflective surface moveable responsive to expansion or contraction of the sample, a displacement sensor system exterior of the cell body, the displacement sensor system having a transmitter for transmitting directed electromagnetic radiation and a sensor for sensing electromagnetic radiation, a lens provided in the cell body, the lens constructed to allow electromagnetic radiation to pass therethrough. The transmitter, reflective surface, and sensor are constructed and positioned such that directed electromagnetic radiation transmitted from transmitter toward reflective surface is reflected from reflective surface toward the sensor. In an exemplary embodiment, the lens is provided in a cell upper plug, with the translating member positioned for linear displacement toward and away from the lens responsive to expansion and contraction of a material sample.