Optical Light Guide Layout for Compact Multipass Concentration Sensing
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Solution Overview
Problem
Existing optical concentration measuring apparatuses using multipass cells with incoherent light sources face challenges in achieving compactness without compromising measurement accuracy, as the light spots spread radially, making it difficult to utilize multipass cells designed for coherent light sources.
Innovation Solution
An optical concentration measuring apparatus is designed with a light guide comprising a first reflector and a second reflector, where the second reflector has two quadric surfaces, and the first reflector has a main reflective surface and two secondary reflective surfaces, arranged to form light spots in a specific pattern on the main reflective surface, allowing for compact design without reducing measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a multipass cell is used with an incoherent light source such as LED, then the apparatus can be made compact, but the light spot spreads radially on the reflective surface making it difficult to maintain measurement accuracy
Solution Approach 1:
The reflective surface is segmented into multiple functional zones: a first reflective surface for initial light reflection, a second reflective surface for guiding light through the measurement cell, and a third reflective surface for directing light to the detector. This segmentation allows each surface to be optimized for its specific function, preventing radial spread and maintaining beam integrity throughout the multipass optical path.
Solution Approach 2:
The patent transitions from a conventional planar mirror arrangement to a three-dimensional folded optical path using multiple reflective surfaces at different orientations. The light path is folded back and forth through the measurement cell using precise angular relationships between reflective surfaces, effectively increasing the optical path length within a compact physical volume while maintaining beam focus.
2Measurement precision
If a multipass cell with elongated reflective region is used, then measurement accuracy is improved, but the apparatus size increases
Solution Approach 1:
The optical path is nested within the compact apparatus housing by folding the light path multiple times through the measurement cell. The reflective surfaces are arranged to create a nested sequence of reflections where the light traverses the measurement region repeatedly in a space-efficient manner, achieving an effective optical path length much longer than the physical dimensions of the apparatus would suggest.
Solution Approach 2:
Instead of extending the optical path linearly in one dimension, the patent uses multiple reflective surfaces to fold the light path through three-dimensional space. The optical path winds through the measurement cell in a compact folded configuration, achieving long effective path length without proportionally increasing the apparatus envelope dimensions.
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
The apparatus achieves a compact form factor while maintaining high measurement accuracy by optimizing light spot distribution and overlap, enabling efficient use of optical path length without increasing size.
Implementation Method 1
the light guide comprises a first reflector and a second reflector... the first reflector comprises a main reflective surface that is a quadric surface and two secondary reflective surfaces integrally formed at portions of the main reflective surface
Data Source
AI summary
An optical concentration measuring apparatus (1) that includes: a light emitter (3) on a main surface (20) of a substrate (2) that emits light from a light-emitting surface; a light receiver (4) on the main surface of the substrate that receives light at a light-receiving surface; and a light guide (5) that guides light emitted by the light emitter to the light receiver. The light guide includes a first reflector (51) and a second reflector (52) that are connected to the main surface of the substrate and are opposite each other in an overhead view of the main surface of the substrate. The second reflector includes two quadric surfaces. The first reflector includes a main reflective surface (53) that is a quadric surface and two secondary reflective surfaces (54) that are quadric surfaces and are integrally formed at portions of the main reflective surface.