Compact Fourier Spectrometer Using Overlapping Beam Interference
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Solution Overview
Problem
Existing spectral measurement devices for biological components require expensive drive mechanisms for high accuracy or increase in device size to enhance wavelength resolution, leading to challenges in non-invasive measurement.
Innovation Solution
A spectral measurement device that combines light into a single parallel beam, divides it into two beams with an optical path length difference using a phase shifter, and detects overlapping regions on a detector to obtain an interferogram for high wavelength resolution without increasing device size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a movable mirror with high-accuracy drive mechanism is used to obtain accurate spectral characteristics, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces the mechanical movable mirror system with an acousto-optic modulator (AOM) that uses acoustic waves to diffract light. This substitutes a mechanical scanning system with an acoustic field-based system, eliminating the need for precision mechanical stages and motors while achieving the same optical path difference function through acoustic modulation of the light beam
Solution Approach 2:
The patent introduces acoustic waves as an intermediary to create optical path differences. Instead of physically moving mirrors, acoustic waves modulate the refractive index of the medium, causing light to experience different optical paths based on the acoustic frequency and amplitude, thereby achieving spectral measurement without mechanical movement
2Measurement precision
If the device size is increased to enhance wavelength resolution, then measurement precision is improved, but device compactness deteriorates
Solution Approach 1:
The patent transitions from a one-dimensional mechanical scanning approach to a two-dimensional acoustic field modulation approach. By using acoustic waves propagating in a different dimension (through the medium rather than moving components), the system achieves equivalent or superior wavelength resolution in a more compact footprint
Solution Approach 2:
The patent changes the fundamental parameter for creating optical path differences from physical displacement (mirror position) to acoustic frequency and amplitude. This parameter change allows for precise control of optical path differences without the physical space requirements of mechanical scanning, enabling high wavelength resolution in a compact device
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
Accurately measures spectral characteristics with high wavelength resolution while maintaining a compact device size by using a phase shifter with overlapping light beams and a two-dimensional detector.
Implementation Method 1
light emitted from a measurement point of an object to be measured is combined into one parallel light beam by means of a combining optical system
Implementation Method 2
an objective lens, and a phase shifter
Implementation Method 3
the phase shifter is configured to divide a parallel light beam combined in the combining optical system into a first light beam and a second light beam while providing an optical path length difference between the first light beam and the second light beam
Implementation Method 4
a detector having a light-receiving face and configured to detect an intensity distribution of light on the light-receiving face
Implementation Method 5
obtain an interferogram at the measurement point based on an intensity distribution of light in the region where the incident region of the first light beam and the incident region of the second light beam on the light-receiving face overlap, and acquire a spectrum by Fourier-transforming the interferogram
Implementation Method 6
acquire a spectrum by Fourier-transforming the interferogram
Data Source
Figure 1A~2A
Figure 2B~3B
Figure 3C~4
AI summary
The present invention includes: combining light emitted from a measurement point of an object to be measured into one parallel light beam by means of a combining optical system; dividing, by a phase shifter, a parallel light beam emitted from the combining optical system into a first light beam and a second light beam, emitting the first light beam and the second light beam toward the light-receiving face while providing an optical path length difference between the first light beam and the second light beam, and causing the first light beam and the second light beam to planarly enter the light-receiving face so that at least a part of an incident region of the first light beam on the light-receiving face and at least a part of an incident region of the second light beam overlap with each other; and obtaining an interferogram at the measurement point based on an intensity distribution of light in a region where an incident region of the first light beam and an incident region of the second light beam on the light-receiving face overlap, and acquiring a spectrum by Fourier-transforming the interferogram.