Monolithic Spectrometer Using Filter Array and Spacer
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Solution Overview
Problem
Spectrometers face challenges in achieving a compact, robust, and cost-effective design with precise assembly, particularly in integrating optical elements above an image sensor array, which complicates manufacturing and increases size and complexity.
Innovation Solution
A monolithic spectrometer design featuring an optical sensor array with a spectral filter array and a transparent spacer, including input apertures that allow light to focus onto each pixel, enabling simpler assembly and reduced height, achieved through wafer-scale processes and subwavelength structures for spectral filtering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a multi-element detector with dispersive elements is used to achieve spectral analysis, then spectral discrimination capability is improved, but device size and complexity increase
Solution Approach 1:
The device segments the spectrum into multiple wavelength bands using a filter array, with each pixel detecting a specific spectral range. This segmentation approach replaces complex rotating gratings with a static multi-pixel detector array, reducing mechanical complexity while maintaining spectral discrimination capability
Solution Approach 2:
The patent adds a spectral dimension to the spatial detection by using a three-dimensional filter array structure. The filter array is positioned at a distance from the detector plane, creating a spectral-spatial mapping where different wavelengths focus at different depths, enabling spectral analysis without mechanical moving parts
2Volume of moving object
If filters are patterned over an image sensor array to create a compact spectrometer, then device size is reduced, but alignment precision requirements increase
Solution Approach 1:
The filter array is pre-positioned at a calculated distance from the detector plane during manufacturing, establishing the spectral-spatial mapping relationship before operation. This preliminary positioning allows for relaxed alignment tolerances during final assembly, as the geometric relationship is determined by the fixed spacing rather than precise lateral alignment
Solution Approach 2:
The patent changes the alignment parameter from lateral positional alignment to axial distance control. By controlling the distance between the filter array and detector plane, the system achieves spectral discrimination with simpler manufacturing processes, as distance control is more feasible than precise lateral alignment of multiple optical elements
3Measurement precision
If an aperture is placed at a fixed distance from the filter array to control light ray angles, then spectral discrimination is improved, but device height increases
Solution Approach 1:
The filter array serves multiple functions simultaneously: it acts as both the spectral filtering element and the light ray angle control element. The three-dimensional positioning of the filter array inherently controls the angle of incidence for different wavelengths, eliminating the need for a separate aperture at a fixed distance and reducing overall device height
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 results in a more compact, robust, and cost-effective spectrometer with improved spectral discrimination capabilities, suitable for diverse space-constrained applications, while maintaining precision and reducing assembly complexity.
Implementation Method 1
a spectral filter array formed over the pixels of the optical sensor array, the spectral filter array filtering incident light such that each pixel receives light of a spectral transmission profile associated with the pixel
Implementation Method 2
a transparent spacer formed over the spectral filter array... the focal length of the dispersive lens varies with different wavelengths of light
Implementation Method 3
an opaque mask having input apertures allowing light through the transparent spacer and onto a portion of the spectral filter array
Data Source
AI summary
In some embodiments, a spectrometer is presented. In accordance with some embodiments, the spectrometer includes an optical sensor array, the optical sensor array including a substrate and an array of pixels formed on the substrate; a spectral filter array formed over the pixels of the optical sensor array, the spectral filter array filtering incident light such that each pixel receives light of a spectral transmission profile associated with the pixel; a transparent spacer formed over the spectral filter array; and an opaque mask having input apertures allowing light through the transparent spacer and onto a portion of the spectral filter array. The spectrometer can be formed from the optical sensor array using a combination of photolithographic techniques and bonding of certain layers.