Optical Waveguide Endface Measurement with Defocus Compensation
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Solution Overview
Problem
Existing methods for measuring optical electric-field distribution at the end surface of optical waveguides, such as multimode fibers, are inaccurate due to uncertainties in the distance between optical system components, leading to unclear image edges and defocus issues.
Innovation Solution
A measurement apparatus and method that generates an interference waveform signal, measures and simulates optical electric-field distributions at multiple planes, and selects a plane with minimized region area to improve measurement accuracy, even with inaccurate component spacing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If digital holography is used to measure optical electric-field distribution, then measurement capability is provided, but measurement precision deteriorates due to defocus and unclear image edges caused by inaccurate distance control between components
Solution Approach 1:
The patent performs preliminary simulation of optical electric-field distribution at multiple planes before final measurement. By pre-calculating and comparing simulated distributions at different distances, the system identifies the correct focal plane and compensates for defocus effects, enabling accurate measurement even when component distances are not precisely controlled
Solution Approach 2:
The patent creates a virtual copy of the optical electric-field distribution through digital simulation. By generating multiple simulated distributions at different planes and comparing them with the measured defocused distribution, the system reconstructs the accurate optical electric-field distribution without requiring precise physical positioning
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
Enhances measurement accuracy of optical electric-field distributions at the end surface of optical waveguides by compensating for defocus without precise control over component distances.
Implementation Method 1
an imaging surface (image sensor) receives interference light of the object light with reference light
Data Source
AI summary
There is provided a measurement apparatus including: an interference waveform generating unit that generates an interference waveform signal corresponding to interference light of first light with second light received by an imaging surface; a distribution measurement unit that measures a first optical electric-field distribution of an intensity and a phase of the first light at the imaging surface, based on the interference waveform signal; a distribution simulation unit that simulates second optical electric-field distributions of the intensity and the phase of the first light at a plurality of planes having different distances from the imaging surface in a direction opposite to a propagation direction of the first light propagated from an end surface of an optical waveguide, based on the measured first optical electric-field distribution; a selection unit that selects, from the plurality of planes, a plane at which an area of a region of the simulated second optical electric-field distributions is minimized; and an output unit that outputs information of the simulated second optical electric-field distributions at the selected plane to a predetermined device.