Image Capture Element with Diffractive Spectroscopy for Low Light Loss
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Solution Overview
Problem
Conventional image capturing elements using color filters suffer from significant light loss, limiting sensitivity due to absorption or reflection, and recent methods involving spectroscopic elements face challenges in integration and signal processing noise, which can degrade image quality.
Innovation Solution
An image capturing element with a pixel array and a spectroscopic element array, where each spectroscopic element has microstructures that spatially separate incident light into different propagation directions based on wavelength, allowing direct conversion to electrical signals without signal processing for color information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If color filters are used for color separation, then color information can be acquired, but light loss occurs due to absorption or reflection, limiting sensitivity
Solution Approach 1:
The patent replaces the conventional color filter system (which relies on absorption and reflection) with a diffractive optical element that uses diffraction to separate wavelengths. This substitution of the underlying physical mechanism eliminates the inherent light loss of color filters while maintaining color separation capability, directly resolving the contradiction between color accuracy and light efficiency
Solution Approach 2:
The patent changes the operational parameters of the optical system by using a diffractive element with specific groove patterns and depths designed to diffract different wavelengths at different angles. This parameter-based approach (controlling diffraction angle through groove geometry) enables full light utilization while achieving accurate color separation, resolving the light loss problem
2Loss of energy
If spectroscopic elements such as prisms or dichroic mirrors are used, then light utilization efficiency can be improved, but integration on photoelectric conversion elements becomes difficult when pixels are finer
Solution Approach 1:
The patent transitions from three-dimensional bulk optical elements (prisms, dichroic mirrors) to a two-dimensional surface-relief diffractive structure that can be directly patterned on the pixel surface. This dimensional reduction enables integration on fine pixels while maintaining spectroscopic functionality, resolving the contradiction between light efficiency and integration difficulty
Solution Approach 2:
The diffractive optical element is implemented as a thin-film surface structure with groove patterns that can be conformally deposited on each pixel. This thin-film approach allows integration on high-resolution pixel arrays where bulk spectroscopic elements would be too large, resolving the integration difficulty while maintaining light utilization efficiency
3Productivity
If signal processing is used to reconstruct color information, then color images can be generated with spectroscopic elements, but signal processing noise can occur, degrading image quality
Solution Approach 1:
The patent performs color separation in advance through the diffractive optical element, directing different wavelengths to different pixels before photoelectric conversion. This preliminary physical separation eliminates the need for subsequent signal processing reconstruction, thereby avoiding signal processing noise while maintaining color image generation capability
Solution Approach 2:
The patent extracts the color separation function from the signal processing domain and implements it in the optical domain through the diffractive element. By taking out the color separation step and performing it optically before detection, the system eliminates the need for noisy computational reconstruction, resolving the contradiction between color image capability and signal noise
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 solution enhances light utilization efficiency and sensitivity by minimizing light loss and signal processing noise, maintaining spatial resolution, and improving color reproducibility without altering microlens or pixel shapes, compatible with existing manufacturing processes.
Implementation Method 1
each of the plurality of spectroscopic elements includes a plurality of microstructures formed from a material having a refractive index higher than a refractive index of the transparent layer, the plurality of microstructures have a microstructure pattern, and each of the plurality of spectroscopic elements separates incident light into deflected light beams having different propagation directions according to a wavelength
Data Source
Figure 1
Figure 2(a)~2(c)
Figure 3(a)~3(b)
AI summary
An image capturing element according to the present disclosure includes a pixel array formed by a plurality of pixels arranged in an array on a substrate, each of the plurality of pixels including a photoelectric conversion element, a transparent layer formed on the pixel array, and a spectroscopic element array formed by a plurality of spectroscopic elements arranged in an array, and each of the plurality of spectroscopic elements is at a position corresponding to one of the plurality of spectroscopic elements inside or on the transparent layer. Each of the plurality of spectroscopic elements includes a plurality of microstructures formed from a material having a refractive index higher than a refractive index of the transparent layer. The plurality of microstructures have a microstructure pattern. Each of the plurality of spectroscopic elements separates incident light into deflected light beams having different propagation directions according to the wavelength and emits the deflected light beams.