Diffraction Grating Pixel Array for Wide-Range Spectral Accuracy
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Solution Overview
Problem
Existing solid-state imaging devices face issues with spectroscopic performance errors due to peak wavelength shifts at high imaging heights, particularly in regions with long wavelengths, leading to inaccurate spectrum representation across wide wavelength ranges.
Innovation Solution
A solid-state imaging device with a pixel array unit and diffraction gratings arranged in a two-dimensional lattice form, where the period of diffraction gratings at different imaging heights is adjusted to maintain accurate spectral characteristics, employing pupil correction to curb peak wavelength shifts by altering the period of the diffraction gratings based on the angle of incidence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the optical distance between metal structures is reduced, then the peak wavelength shift is decreased in short wavelength range, but the spectroscopic performance errors occur in long wavelength range and high imaging height regions
Solution Approach 1:
The patent applies local quality by setting different periods for diffraction gratings at different imaging heights. Specifically, the period of diffraction gratings is made shorter in regions with high imaging height (oblique incidence) and longer in regions with low imaging height (near-axis incidence). This spatially varying period distribution compensates for the wavelength shift caused by oblique incidence at different heights, thereby maintaining accurate spectroscopic performance across the entire imaging field without sacrificing long wavelength range coverage.
2Device complexity
If a single period diffraction grating is used, then the device complexity is reduced, but the spectral accuracy deteriorates at high imaging heights with oblique light incidence
Solution Approach 1:
The patent implements dynamics by transitioning from a static, uniform diffraction grating period to a dynamic, spatially varying period distribution. The period of the diffraction grating is adjusted according to the imaging height, creating a gradient structure where the period changes continuously or in steps across the imaging field. This dynamic adaptation of the grating period to local incidence conditions maintains spectral accuracy across different field positions without requiring complex mechanical adjustments.
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 solution ensures consistent spectral performance across various imaging heights, enhancing the accuracy of image data acquisition in applications like agricultural vegetation evaluation and biometric detection by preventing peak wavelength shifts to longer wavelengths.
Implementation Method 1
a plurality of diffraction gratings provided in one-to-one corresponding to light-receiving surfaces of the plurality of photoelectric conversion elements
Implementation Method 2
a plurality of photoelectric conversion elements are arranged in a two-dimensional lattice form
Data Source
AI summary
Spectral performance in a wide wavelength range is improved. A solid-state imaging device according to an embodiment includes: a pixel array unit in which a plurality of photoelectric conversion elements (PD) are arranged in a two-dimensional lattice form; a plurality of diffraction gratings provided corresponding one-to-one to light-receiving surfaces of the plurality of photoelectric conversion elements; and pixel circuits configured to generate pixel signals on the basis of charge accumulated in the photoelectric conversion elements, wherein a period of a first diffraction grating positioned at a first imaging height is different from a period of a second diffraction grating positioned at a second imaging height different from the first imaging height.