Compact Spectrometer Using Birefringent Optics for Mobile Devices

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Solution Overview

Problem

Existing spectrometers are bulky, expensive, and require extensive processing power and mechanical scanning, making them unsuitable for use with mobile devices and limiting their adoption for field applications, especially in terms of spectral accuracy and convenience.

Innovation Solution

A compact spectrometer design using fringe generating optics and birefringent optics integrated with digital cameras, which captures spectral signatures in a single snapshot without mechanical scanning, utilizing the processing power of mobile devices and a diffuser for uniform illumination to reduce noise and computational complexity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If mechanical scanning is used to capture spectral signatures, then spectral measurement capability is improved, but device complexity and measurement time increase

Engineering Contradiction:
Improvespectral measurement capabilityVSAvoidmechanical scanning complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces mechanical scanning systems with a static optical setup comprising a diffuser, birefringent optics, and a camera. Light from the object passes through the diffuser to create uniform illumination, then through birefringent optics that generate interference patterns encoding spectral information. The camera captures these patterns in a single snapshot, eliminating mechanical moving parts while maintaining spectral measurement capability through computational processing of the interference patterns.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If mechanical scanning is used to capture spectral signatures, then spectral measurement capability is improved, but measurement time increases

Engineering Contradiction:
Improvespectral measurement capabilityVSAvoidmeasurement time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent uses periodic interference patterns generated by birefringent optics to encode spectral information across multiple pixels simultaneously. The interference fringes create a spatial modulation of light intensity that corresponds to different optical path differences, allowing the entire spectral range to be captured in a single exposure without sequential scanning. This parallel acquisition approach dramatically reduces measurement time while preserving spectral measurement capability.

Inventive Principle:
Principle #19Periodic action

3Measurement precision

If extensive computational processing is used to process multiple images, then spectral signature accuracy is improved, but processing power requirements increase

Engineering Contradiction:
Improvespectral signature accuracyVSAvoidprocessing power requirements
Core Design Contradiction:
Measurement precisionVSPower

Solution Approach 1:

The patent extracts spectral information directly from spatial interference patterns captured in a single image, rather than requiring extensive processing of multiple sequential images. The birefringent optics create interference fringes where the spatial position and intensity encode spectral data, allowing spectral signatures to be derived through simpler computational methods applied to a single snapshot, thereby reducing processing power requirements while maintaining accuracy.

Inventive Principle:
Principle #2Taking out (Extraction)

4Ease of operation

If a compact design is implemented for portability, then ease of operation is improved, but optical performance may deteriorate

Engineering Contradiction:
Improveportability and convenienceVSAvoidoptical performance
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The patent merges multiple optical functions into a compact integrated system. The diffuser, birefringent optics, and camera sensor are combined in a single portable device that fits within or attaches to a mobile device. The compact design maintains optical performance by carefully designing the optical paths and using high-quality optical elements, enabling spectral measurements to be performed portably without significant performance degradation.

Inventive Principle:
Principle #5Merging (Combining)

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 accurate and rapid spectral analysis with high fidelity, reducing noise through averaging of multiple signatures, and allowing for portable, user-friendly spectral measurement in various applications, including material analysis and environmental monitoring.

Implementation Method 1

One type of Fourier Transform interferometer uses birefringent optics to create polarization modulation with the angle of incidence of light and generate fringes across the field of view of an optical imager

Methodology Applied
Scientific EffectBirefringence: Birefringence

Implementation Method 2

uses birefringent optics to create polarization modulation with the angle of incidence of light and generate fringes

Methodology Applied
Scientific EffectPolarization modulation: Polarisation

Implementation Method 3

utilizing the processing power of mobile devices and a diffuser for uniform illumination to reduce noise and computational complexity

Methodology Applied
Scientific EffectDiffusion: Diffusion

Implementation Method 4

The Fourier transform of a resulting interferogram corresponds to the spectral signature of incoming light

Methodology Applied
Scientific EffectFourier transform:

Implementation Method 5

based on two-beam interference or polarization modulation phenomenon to generate a resulting interferogram

Methodology Applied
Scientific EffectInterference: Interference

Data Source

PatentEP3056880B1Compact spectrometer
Publication Date: 2023.09.27 LIGHTHAUS PHOTONICS
  • EP3056880B1 patent drawingFigure 1~3
  • EP3056880B1 patent drawingFigure 4~5
  • EP3056880B1 patent drawingFigure 6

AI summary

A spectrometer (10) for measuring a spectral signature of an object comprises fringe generating optics (12) for use with a camera (65) and a processor. The fringe generating optics are formed of front optics (45) and birefringent optics (55). The front optics comprises a diffuser adapted to receive light from the object. The birefringent optics is adapted to receive light from the diffuser and to generate interference fringes. The camera is adapted to receive the interference fringes and the processor generates the spectral signature of the object. This spectrometer is an improved Fourier transform spectrometer suitable for use with digital cameras, such as cameras found in mobile devices.