Coaxial Spectrograph Eliminates Coma via Integrated Grating
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Solution Overview
Problem
Traditional grating monochromators suffer from optical coma defects due to off-axis optical paths, which are difficult to eliminate completely, leading to reduced light intensity and limited wavelength resolution in high-performance spectrograph applications.
Innovation Solution
A broadband high-resolution spectrograph design featuring an integrated grating with multiple sub-gratings, a collimating mirror, and a two-dimensional focus imaging mirror, utilizing a coaxial optical path to eliminate coma, with a light through hole in the integrated grating and a two-dimensional area array detector for high-speed and high-resolution detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If an off-axis optical path is adopted in traditional grating monochromator, then the optical structure can be simplified, but optical coma defects are generated leading to reduced measurement precision
Solution Approach 1:
The patent inverts the traditional off-axis optical path design by adopting a coaxial optical path where the incident light and diffracted light share the same optical axis. This inversion eliminates the optical coma defects inherent in off-axis designs while maintaining structural simplicity through the use of a reflection grating positioned perpendicular to the optical axis.
Solution Approach 2:
The patent segments the optical system into distinct functional components: a collimation lens for parallelizing incident light, a reflection grating for wavelength separation, and a focusing lens for concentrating diffracted light. This segmentation allows each component to be optimized independently, achieving high measurement precision without complex overall structure.
2Adaptability or versatility
If a mechanical transmission device is used to rotate the grating for wavelength scanning, then wavelength selection capability is achieved, but the device complexity and potential mechanical errors increase
Solution Approach 1:
The patent replaces the mechanical transmission device with an electrical control system. A rotating driver equipped with a rotary encoder directly drives the grating rotation, eliminating intermediate mechanical transmission components. This substitution reduces device complexity and potential mechanical errors while maintaining full wavelength scanning capability through electrical control.
3Device complexity
If the positions of incident slits and exit slits are fixed, then the optical structure is simplified, but wavelength scanning requires mechanical rotation of the grating
Solution Approach 1:
The patent maintains fixed incident and exit slit positions to simplify the optical structure, while replacing the mechanical grating rotation with an electrically controlled rotating driver. This allows wavelength scanning to be operated simply by controlling the rotation angle of the grating via electrical signals, improving ease of operation without compromising structural simplicity.
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 coaxial optical system effectively eliminates coma, enhancing measurement accuracy and resolution across the full spectrum without mechanical displacement, allowing for non-destructive passage of spectrum signals and reliable filtering of high-order diffraction light.
Implementation Method 1
An optical collimating system is adopted to collimate and convert incident light to become parallel light incident to a grating
Implementation Method 2
A required wavelength or wavelength region is separated out from electromagnetic radiation of a radiation source by a dispersion element
Implementation Method 3
According to a principle of grating diffraction: d sin θm=mλ+go
Implementation Method 4
An optical focusing system is adopted to focus diffraction light with different wavelengths from the grating and gather the diffraction light on a focal plane of the detector
Implementation Method 5
A device adopting a photodetector such as a photomultiplier to measure intensity of different wavelength positions of a spectrum line
Data Source
AI summary
The present invention discloses a coma-elimination broadband high-resolution spectrograph, comprising incident slits, a collimating mirror, an integrated grating, a two-dimensional focus imaging mirror and a two-dimensional area array detector, wherein the incident slits enters along the incident slits, passes through a light through hole in the center of the integrated grating and is incident to the collimating mirror, the incident light enters the integrated grating along a coaxial optical path L1 after collimation of the collimating mirror and is focused by the two-dimensional focus imaging mirror after diffraction of each sub-grating, diffraction light in full spectrum region enters a focal plane of the two-dimensional area array detector for detection along an coaxial optical path L2, and off-axis angles of the L1 and the L2 are zero.