Wavelength-Swept Light Measurement with Optical Path Switching
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Solution Overview
Problem
Existing wavelength swept-type spectroscopy systems face issues with photodetector damage due to high-power laser beams when measuring low-light-transmittance and high-diffusivity objects, and conveyor systems cause direct laser incidence on photodetectors due to gaps or missing products, leading to reliability concerns.
Innovation Solution
Incorporation of an optical path switching element or light shielding mechanism controlled by a controller to divert or block wavelength swept light based on the presence of the target object, protecting the photodetector from direct high-power laser exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a high-power pulsed laser is used to increase transmitted light power for low light transmittance objects, then measurement capability for low transmittance objects is improved, but photodetector reliability deteriorates due to direct laser incidence when products are absent or displaced
Solution Approach 1:
A beam splitter is introduced as an intermediary element to divide the optical path. The beam splitter separates the incident light into reflected light (for photodetector monitoring) and transmitted light (for product measurement), enabling independent monitoring of laser power without exposing the photodetector to full laser intensity during normal operation
Solution Approach 2:
The optical system is segmented into multiple detection paths: a reflected light path for monitoring laser power and an absent product detection path. This segmentation allows the system to monitor laser conditions and detect absent products without directing full laser power to the photodetector, resolving the contradiction between measurement capability and photodetector safety
2Productivity
If automatic high-speed conveyor is used to increase productivity, then production efficiency is improved, but product displacement or absence occurs causing direct laser incidence on photodetector
Solution Approach 1:
The system performs preliminary detection by monitoring reflected light before transmitted light reaches the photodetector. When product absence or displacement is detected through reflected light analysis, the system can take preliminary protective actions or flag the measurement as invalid, preventing direct laser incidence damage while maintaining high-speed conveyor operation
Solution Approach 2:
A feedback mechanism is established where reflected light intensity is continuously monitored and fed back to indicate product presence. This feedback loop enables real-time detection of absent or displaced products on the high-speed conveyor, allowing the system to respond appropriately and prevent photodetector damage while maintaining productivity
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
Effectively prevents photodetector damage by diverting or attenuating high-power light when no object is present, ensuring reliable operation and extending photodetector lifespan.
Implementation Method 1
a light receiver structured to measure an object light ascribed to the wavelength swept light transmitted through the target object to be measured
Implementation Method 2
an optical path switching element provided to an optical path of the wavelength swept light, and is structured to switch the optical path of the wavelength swept light
Data Source
AI summary
The light source apparatus produces wavelength swept light. An irradiation optical system irradiates a measurement position with the wavelength swept light. A conveyor conveys a sample so as to pass it through the measurement position. A light receiver measures an object light ascribed to the wavelength swept light transmitted through the sample. An optical path switching element is provided to an optical path of the wavelength swept light, and switches the optical path of the wavelength swept light. A controller controls the optical path switching element, depending on presence or absence of the target object to be measured.