Diffraction Grating for Solid-State Imaging Ghost Suppression
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Solution Overview
Problem
Solid-state imaging apparatuses face challenges in suppressing the occurrence of ghost (flare) in captured images due to reflected diffraction light, particularly in 'cavity-less' structures where fine pixels lead to radial ghosting and in 'cavity' structures where high-wavelength components cause 'red-ball' ghosting.
Innovation Solution
Incorporating a diffraction grating between the transparent substrate and the sensor substrate to diffract and transmit reflected diffraction light, thereby reducing its intensity and minimizing ghosting effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a cavity-less structure is used to prevent warping and peeling, then structural stability is improved, but ghosting due to total reflection of reflected diffraction light increases
Solution Approach 1:
A diffraction grating is introduced as an intermediary element between the cover glass and the pixel array. This diffraction grating receives the reflected diffraction light and diffracts it again, preventing total reflection and guiding the light to escape through the cover glass surface, thereby eliminating ghosting while maintaining the cavity-less structure's structural stability
Solution Approach 2:
The refractive index distribution is modified by introducing the diffraction grating structure with different refractive index regions. This changes the optical parameters of the system, allowing controlled diffraction and escape of reflected diffraction light, thus resolving the ghosting issue without compromising structural integrity
2Manufacturing precision
If fine pixels are arranged to increase resolution, then image detail is improved, but radial ghosting around high-luminance subjects increases
Solution Approach 1:
The diffraction grating serves as a mediator that intercepts reflected diffraction light before it can form radial ghosts around high-luminance subjects. By diffracting the light again, it redirects the energy away from forming ghost images, allowing fine pixel arrangements to maintain their resolution advantage without the penalty of radial ghosting
3Manufacturing precision
If a reflection-type infrared cut filter is provided to enhance visible light image quality, then color accuracy is improved, but red-ball ghosting increases
Solution Approach 1:
The diffraction grating is positioned to act before the infrared cut filter, intercepting and diffracting the reflected diffraction light that would otherwise reflect off the infrared cut filter and create red-ball ghosts. This intermediary action prevents the harmful reflection while allowing the infrared cut filter to maintain its color accuracy enhancement function
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 diffraction grating effectively disperses and reduces the intensity of reflected diffraction light, enhancing image quality by minimizing ghosting and improving captured image clarity.
Implementation Method 1
a diffraction grating which is provided at any position between an upper surface of the transparent substrate and the upper surface of the sensor substrate and transmits incident light H therethrough and is formed so as to diffract reflected diffraction light HK
Data Source
AI summary
A solid-state imaging apparatus including: a sensor substrate that has a plurality of pixels configured to receive incident light, the plurality of pixels being arranged on an upper surface of a semiconductor substrate; a transparent substrate that has a lower surface facing an upper surface of the sensor substrate and is configured to transmit the incident light therethrough; and a diffraction grating that is provided at any position between an upper surface of the transparent substrate and the upper surface of the sensor substrate and is configured to transmit the incident light therethrough, in which the diffraction grating is formed so as to diffract reflected diffraction light caused by that the incident light is incident on a pixel area in which the plurality of pixels are arranged on the upper surface of the semiconductor substrate and is diffracted.