Freeform Prism Spectrometer Resolving Optical Throughput
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Solution Overview
Problem
Conventional spectrometers, particularly those using diffraction gratings, suffer from poor light efficiency and complex order sorting filters, leading to detrimental effects on image quality metrics such as modulation transfer function, optical transfer function, spot size, wavefront error, optical throughput, total dispersion, and image distortion.
Innovation Solution
The design incorporates a spectrometer with a freeform prism-based optical guide device that includes a focusing optic with freeform surfaces, such as cylindrical, acylindrical, or substantially flat surfaces with polynomial terms, to improve image correction and resolution, offering advantages over diffraction grating-based systems by using computer-aided design to manufacture highly specialized and unique surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If diffraction grating-based optical systems are used, then spectral dispersion is achieved, but light efficiency deteriorates and image quality metrics (modulation transfer function, optical transfer function, spot size, wavefront error, optical throughput) deteriorate
Solution Approach 1:
The patent replaces the diffraction grating (mechanical/optical element) with a refractive prism-based system. The prism uses refraction to achieve spectral dispersion instead of diffraction, eliminating the need for complex order sorting filters and improving light efficiency while maintaining spectral separation capabilities.
Solution Approach 2:
The patent changes the optical element parameter from diffraction grating to refractive prism. This parameter change fundamentally alters how spectral dispersion is achieved, improving light efficiency and image quality by using refraction instead of diffraction, and eliminating the need for additional order sorting filters.
2Measurement precision
If diffraction grating-based systems are used, then spectral components are separated, but optical throughput deteriorates due to complex order sorting filters
Solution Approach 1:
The patent extracts and removes the complex order sorting filters from the optical system. By using a refractive prism instead of a diffraction grating, the system achieves spectral component separation without requiring these additional filtering elements, thereby improving optical throughput by eliminating energy loss in the filters.
Solution Approach 2:
The patent substitutes the diffraction grating system with a refractive prism system that inherently provides spectral separation without order sorting filters. This substitution eliminates the energy loss associated with filter transmission and reflection, improving overall optical throughput.
3Measurement precision
If conventional optical elements are used, then basic spectral separation is achieved, but image correction and resolution deteriorate
Solution Approach 1:
The patent applies local quality by designing optical elements (prisms and mirrors) with specific surface curvature characteristics tailored to correct local aberrations. The optical elements have customized surface profiles that provide localized correction for image quality issues, improving overall image correction and resolution while maintaining spectral separation.
Solution Approach 2:
The patent utilizes curved surfaces (spheroidality) in the design of optical elements to correct imaging aberrations. By incorporating specific curvature characteristics in prisms and mirrors, the system achieves improved image correction and resolution while maintaining the spectral separation function.
4Ease of operation
If standard optical designs are used, then basic imaging is achieved, but distortion correction deteriorates
Solution Approach 1:
The patent employs asymmetric surface designs in optical elements to correct distortion. By using non-symmetric surface profiles and curvature distributions, the system corrects imaging distortion while maintaining basic imaging functionality, improving the shape accuracy of the output image.
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 approach results in significant improvements in image quality, distortion correction, and optical throughput, providing high-resolution, well-corrected imaging fields with reduced anamorphic distortion and improved wavefront error correction.
Implementation Method 1
a first prism positioned in the optical path... The first prism can comprise at least one freeform prism surface
Implementation Method 2
a focusing optic positioned in the optical path... configured to guide electromagnetic radiation along the optical path
Data Source
AI summary
A spectrometer is configured to form a spectrally resolved image of electromagnetic radiation from an electromagnetic radiation source. The spectrometer can include an optical guide device configured to guide electromagnetic radiation along an optical path. The optical guide device can include a first prism positioned in the optical path. The optical guide device can further include a focusing optic. The first prism can include at least one freeform prism surface that comprises at least some degree of cylindrical curvature having freeform polynomial terms formed thereon, which surface can be a substantially cylindrical, a substantially acylindrical, or a substantially flat surface having freeform polynomial terms formed thereon.