Time-Wavelength Pulsed Spectroscopy for Fast Product Inspection
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Solution Overview
Problem
Conventional spectroscopic measurement techniques, such as those using diffraction gratings and Fourier transform spectroscopy, are limited by their need for scanning, making high-speed and high signal-to-noise ratio (SNR) measurements challenging, particularly for product inspection applications.
Innovation Solution
A spectroscopic measurement method utilizing pulsed light with a one-to-one correspondence between elapsed time and wavelength, combined with integration of light receiver outputs and a configuration that includes an ultrashort pulsed laser source, nonlinear element, and arrayed waveguide diffraction grating to enhance measurement speed and SNR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If scanning methods (diffraction grating or Fourier transform spectroscopy) are used, then spectral measurement can be performed, but measurement speed is limited due to the need for mechanical scanning
Solution Approach 1:
The patent replaces mechanical scanning systems with a pulse-based optical measurement approach. By using pulsed light sources and time-gated detection, the system eliminates the need for mechanical diffraction grating rotation or mirror scanning, achieving high-speed spectral measurement without moving parts.
Solution Approach 2:
The patent employs periodic pulsed illumination at high repetition rates to acquire spectral information. By synchronizing the detection window with each light pulse and accumulating signals over multiple periods, the system achieves both high speed and high signal-to-noise ratio without mechanical scanning.
2Reliability
If multiple pulses are integrated to improve SN ratio, then measurement accuracy improves, but measurement time increases
Solution Approach 1:
The patent performs preliminary time-gating of the detection window synchronized with each light pulse before integration. This pre-synchronization ensures that only relevant signal photons are collected during the active illumination window, reducing background noise accumulation and enabling faster integration to achieve high SN ratio.
Solution Approach 2:
The patent maintains continuous pulsed illumination at high repetition rates with continuous synchronized detection and integration. This continuous operation allows rapid accumulation of signal photons without interruption, achieving high SN ratio in minimal time compared to sequential scanning methods.
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 high-speed spectroscopic measurements with improved SNR, suitable for real-time product inspection by integrating light receiver outputs and using pulsed light to achieve accurate quality determination.
Implementation Method 1
causing ultrashort pulsed laser light from an ultrashort pulsed laser source to be incident on a nonlinear element to generate a nonlinear effect, so that the ultrashort pulsed laser light is broadened
Implementation Method 2
the broadband pulsed light emitted from the nonlinear element is wavelength-divided by an arrayed waveguide diffraction grating
Implementation Method 3
divided pulsed light that is the broadband pulsed light having been wavelength-divided is transmitted through delay fibers to be delayed
Implementation Method 4
a light receiver is disposed at the condensed position and the light is detected
Data Source
AI summary
Pulsed light in which an elapsed time in a pulse and a wavelength of light correspond to each other on a one-to-one basis is emitted from a pulsed light source and radiated to a product multiple times, and a plurality of beams of the pulsed light transmitted through the product is incident on a light receiver. An output of the light receiver is digitized by an AD converter, values at times regarded as having the same wavelength in beams of the pulsed light are integrated by an FPGA as an integration unit, and then the integrated value is input to a calculator, an absorption spectrum is calculated by a measurement program, and a quality determination program quantifies a specific component to determine quality of a product.