Monolithic Spectrometer Segmented Focusing Surface

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Solution Overview

Problem

Existing monolithic spectrometers face challenges in covering a broad wavelength range while maintaining adequate spectral resolution, as they often compromise on resolution when imaging wavelengths far apart in the electromagnetic spectrum.

Innovation Solution

A monolithic spectrometer with a segmented focusing surface, featuring distinct focusing sections separated by optical discontinuities, allows independent adaptation of imaging positions for different wavelength ranges, enabling the simultaneous imaging of widely spaced wavelengths on a single-line sensor without deteriorating resolution. This design includes a grating surface for wavelength-dependent diffraction and collimating surfaces for beam guidance, along with optional band filters for managing overlapping wavelength ranges.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single continuous focusing surface is used in a monolithic spectrometer, then the device structure is simple, but the spectral resolution deteriorates when imaging wavelengths far apart in the electromagnetic spectrum

Engineering Contradiction:
Improvefocusing surface structureVSAvoidspectral resolution
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The focusing surface is divided into multiple discrete focusing sections, each optimized for specific wavelength ranges. This segmentation allows each section to independently adapt imaging positions for different wavelengths, thereby maintaining high spectral resolution across broad wavelength ranges without requiring a complex single continuous surface

Inventive Principle:
Principle #1Segmentation

2Measurement precision

If the imaging position is adapted for one wavelength range, then the resolution for that range is improved, but the image size (spatial extent) changes, making it difficult to image multiple wavelength ranges on a single-line sensor

Engineering Contradiction:
Improvespectral resolutionVSAvoidwavelength range coverage
Core Design Contradiction:
Measurement precisionVSAdaptability or versatility

Solution Approach 1:

By segmenting the focusing surface into multiple independent sections, each section can be independently adapted to image different wavelength ranges at different positions along the spectral axis. This allows multiple wavelength ranges to be simultaneously imaged on a single-line sensor while maintaining optimal resolution for each range

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent utilizes the spatial dimension along the spectral axis to accommodate multiple wavelength ranges. Each focusing section projects its wavelength range to a distinct position along this axis, enabling multiplexed imaging of broad spectral ranges without compromising the resolution adaptation for individual wavelength ranges

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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

The segmented focusing surface allows for improved spectral resolution and compactness, enabling the spectrometer to cover a broad wavelength range effectively, with enhanced resolution and signal strength for steep angles of incidence, particularly suitable for applications like LIBS spectroscopy.

Implementation Method 1

The optical surfaces comprise a collimating surface configured to receive the entry beam directed along the first part of the optical path and to reflect the entry beam as a collimated beam directed along a second part of the optical path

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 2

The optical surfaces comprise a grating surface configured to receive the collimated beam directed along the second part of the optical path and to reflect diffracted beams in different directions along a third part of the optical path according to a wavelength dependent diffraction angle

Methodology Applied
Scientific EffectDiffraction: Diffraction

Implementation Method 3

The first focusing section has a first continuously functional optical shape to focus, along one part of the optical path, all received parts of the first diffracted beam with the first wavelength onto a first focal position in an imaging plane outside the body

Methodology Applied
Scientific EffectFocusing: Focusing

Data Source

PatentEP3400428B1High resolution broadband monolithic spectrometer and method
Publication Date: 2022.03.02 NEDERLANDSE ORG VOOR TOEGEPAST NATUURWETENSCHAPPELIJK ONDERZOEK TNO
  • EP3400428B1 patent drawingFigure 1
  • EP3400428B1 patent drawingFigure 2
  • EP3400428B1 patent drawingFigure 3

AI summary

A monolithic spectrometer (10) for spectrally resolving light (L), comprises a body (2) of solid material having optical surfaces (3,4,5,6a-6c,8) configured to guide the light (L) along an optical path (E1,E2,E3,E4) inside the body (2). The optical surfaces of the body (2) comprise a segmented focusing surface (6a,6b) comprising first and second continuously functional optical shapes (Ca,Cb) to focus received parts of respective beams (La,Lb) onto respective focal position (fa,fb) in an imaging plane (P) outside the body (2). The second continuously functional optical shape (Cb) is separated from the first continuously functional optical shape (Ca) by an optical discontinuity (Dab) there between.