Spectrometer with Coinciding Optical Axis for Aberration Correction
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Solution Overview
Problem
Conventional spectrometers generating two-dimensional spectra face challenges in stability and manufacturability due to optical aberrations and sensitivity to component placement accuracy, particularly with the alignment of imaging mirrors and correction lenses.
Innovation Solution
The spectrometer design incorporates a main grating and a cross dispersion element with an imaging mirror and correction lens having a coinciding axis of cylindrical symmetry, allowing for improved placement accuracy and stability, and using a field flattening lens to correct optical aberrations, enabling a more compact and efficient two-dimensional spectrum imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional spectrometer design with imaging mirror and correction lens is used, then two-dimensional spectrum imaging is achieved, but optical aberrations and sensitivity to component placement accuracy occur
Solution Approach 1:
The patent employs an asymmetric optical path design where the light path folds back on itself, with the imaging mirror and correction lens positioned such that the optical path forms a U-shape. This asymmetric arrangement allows the optical components to be placed closer together while maintaining proper optical functionality, reducing the overall instrument size without compromising imaging quality or requiring extreme placement precision
Solution Approach 2:
The patent implements a nested optical configuration where the correction lens is positioned within the focal region of the imaging mirror, and the main grating is arranged to fold the light path back through the same spatial region. This nesting allows multiple optical components to occupy overlapping or adjacent spatial zones, significantly compacting the instrument while maintaining optical performance
2Measurement precision
If conventional spectrometer design is used, then two-dimensional spectrum imaging is achieved, but stability is reduced due to thermal shifts and optical aberrations
Solution Approach 1:
The patent incorporates a correction lens specifically positioned to counteract optical aberrations introduced by the imaging mirror and grating configuration. The lens is pre-adjusted during assembly to compensate for spherical aberration and other optical defects, providing preliminary correction that stabilizes imaging quality against thermal drift and other environmental variations during operation
Solution Approach 2:
The correction lens acts as an intermediary optical element between the imaging mirror and the detector plane, mediating the optical path to correct aberrations. This intermediate correction stage stabilizes the overall optical system by compensating for variations introduced by other components, thereby improving long-term stability without requiring the entire system to be perfectly rigid
3Volume of moving object
If compact spectrometer design is implemented, then instrument size is reduced, but component placement accuracy becomes more critical
Solution Approach 1:
The patent merges the functions of multiple optical components into a compact folded optical path, where the imaging mirror and correction lens share overlapping spatial regions. By combining their optical functions within a reduced volume and using common mounting structures, the system achieves compactness without proportionally increasing placement precision requirements
Solution Approach 2:
The patent utilizes a folded optical path that extends in multiple spatial dimensions rather than a linear arrangement. The light path folds back on itself in the lateral dimension, allowing the optical components to be positioned closer together in the longitudinal dimension. This dimensional reconfiguration reduces overall instrument length while maintaining adequate separation and alignment tolerances for the components
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
This design enhances the stability and manufacturability of the spectrometer by reducing optical aberrations and accommodating thermal shifts, allowing for a more compact and efficient two-dimensional spectrum imaging with improved detector array compatibility.
Implementation Method 1
a main grating (3) arranged for spectrally dispersing radiation entering the spectrometer along a main dispersion direction
Implementation Method 2
a cross dispersion element (2) arranged for separating diffraction orders of the main grating by means of spectrally dispersing the radiation in a cross dispersion direction
Implementation Method 3
an imaging mirror (4) arranged for reflecting and focussing dispersed radiation from the main grating towards an image plane
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
The present disclosure concerns a spectrometer (10) and method for generating a two dimensional spectrum (S). The spectrometer (10) comprises a main grating (3) and cross dispersion element (2). An imaging mirror (4) is arranged for reflecting and focussing dispersed radiation (R3) from the main grating (3) towards an image plane (IP) for imaging the two dimensional spectrum (S) onto an image plane (IP) of the spectrometer (10). A correction lens (6) is arranged for correcting optical aberrations in the imaging of the two dimensional spectrum (S) in the image plane (IP). The imaging mirror (4) and correction lens (6) have a coinciding axis of cylindrical symmetry (AS).