Optical Measurement Device Variable Path Length Flow Cell
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Solution Overview
Problem
Conventional optical measurement devices for liquid chromatography require frequent replacement of flow cells with different optical path lengths to adjust for varying sample concentrations, which is time-consuming and labor-intensive, and existing solutions to change optical path length involve large and costly mechanisms for adjusting light incidence angles.
Innovation Solution
An optical measurement device with an optically transparent sample cell and a detecting unit that includes a photodetector and a connecting element with a higher refractive index than the cell material, allowing the detection unit to be positioned along the cell's surface to change the effective optical path length by altering the attachment position, thereby adjusting the optical path length without replacing the cell or changing the light incidence angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If flow cells with different optical path lengths are used to adjust for varying sample concentrations, then detection sensitivity is improved, but device complexity and operation time increase due to the need to replace flow cells
Solution Approach 1:
A single flow cell is designed to perform multiple functions by enabling variable optical path length measurement through changes in light incidence angle. The flow cell can measure both high-concentration samples (with direct transmission) and low-concentration samples (with increased reflections) without replacement, making one cell serve multiple purposes that previously required multiple specialized cells.
2Measurement precision
If flow cells are replaced to change optical path length, then detection sensitivity is improved, but loss of time and labor increase
Solution Approach 1:
The optical path length is made dynamically adjustable by changing the light incidence angle rather than being fixed in each flow cell. This dynamic adjustment allows the system to adapt to different measurement requirements (high or low concentration samples) without physical replacement of components, eliminating the time-consuming process of swapping flow cells while maintaining optimal detection sensitivity.
3Adaptability or versatility
If a mechanism is added to adjust light incidence angle to change optical path length, then adaptability is improved, but device size and cost increase
Solution Approach 1:
The optical path length is adjusted by changing the parameter of light incidence angle directly, without requiring complex mechanical mechanisms. By controlling the angle at which light enters the flow cell, the system achieves variable optical path length measurement capability through a simple parameter change rather than through mechanical movement or additional components.
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
Enables flexible adjustment of optical path length according to sample concentration and analysis needs, reducing labor and time, eliminating the need for multiple flow cells and large mechanical adjustments, while maintaining device compactness and precision.
Implementation Method 1
a connecting element which is placed between the sample cell and the photodetector element in such a manner as to have a portion being in contact with the outer surface of the sample cell, the connecting element being made of a material which allows transmission of light and whose refractive index is higher than the refractive index of the material of the wall of the sample cell
Implementation Method 2
a photodetector element for performing photoelectric conversion
Data Source
AI summary
Measurement light is cast from a light-casting unit into a flow cell. The light is repeatedly reflected at an outer surface of the flow cell. A detecting unit including a connecting element and a photodetector element is provided in contact with the outer surface of the flow cell. Since the connecting element is made of a material whose refractive index is higher than that of the wall of the flow cell, the light is extracted from the flow cell at the contact position of the connecting element, to be detected by the photodetector element. A shift of the attachment position of the detecting unit along the axis of the flow cell changes the optical path length of the measurement light. A high-sensitivity absorption measurement can be performed by controlling the optical path length by merely changing the attachment position of the detecting unit, without replacing the flow cell.