Multi-Sensor Image Pickup Apparatus Balancing Wavelength Sensitivity
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Solution Overview
Problem
Conventional image sensors face challenges in capturing multi-band images due to decreased sensitivity at wavelengths away from the center wavelength, leading to luminance saturation and reduced signal-to-noise ratio, especially in near-ultraviolet and near-infrared ranges, which affects spectral analysis and data accuracy.
Innovation Solution
The image pickup apparatus employs a spectral optical system with a controller that adjusts exposure conditions for each wavelength range, using a pushbroom type imaging system and a control system to balance luminance values, eliminating the need for optical filters and optimizing light utilization by inverting the wavelength sensitivity graph to maintain constant luminance across spectral ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single image sensor captures multiple wavelengths simultaneously, then the device complexity is reduced, but the signal intensity distribution becomes uneven and the dynamic range is limited for low sensitivity wavelengths
Solution Approach 1:
The image sensor is divided into multiple sensor units, with each unit dedicated to capturing a specific wavelength range. This segmentation allows each sensor unit to be optimized for its designated wavelength, ensuring uniform signal intensity across all captured bands while maintaining relatively simple device architecture.
2Measurement precision
If the transmittance of bandpass filter is adjusted to balance signal intensity, then the signal distribution is improved, but the incident light utilization efficiency decreases
Solution Approach 1:
The patent removes the bandpass filter component from the optical path and instead uses separate sensor units for each wavelength range. This extraction of the filtering function allows incident light to pass through to the sensor directly, maximizing light utilization efficiency while maintaining balanced signal intensity through the sensor unit design.
Solution Approach 2:
The patent changes the fundamental parameter of wavelength selection from optical filtering (bandpass filter transmittance) to sensor-level wavelength assignment. Each sensor unit is assigned to detect a specific wavelength range, fundamentally changing how wavelength selection is achieved and eliminating the need for light-dimming filtering operations.
3Measurement precision
If exposure time is extended to improve signal intensity for low sensitivity wavelengths, then the signal-to-noise ratio improves, but the acquisition time increases
Solution Approach 1:
By segmenting the sensor into wavelength-specific units, each sensor unit can be optimized for its designated wavelength range, allowing for optimal exposure settings for each band simultaneously. This eliminates the need to extend exposure time for low sensitivity wavelengths while maintaining fast acquisition speeds.
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 allows for efficient acquisition of multi-band images with balanced signal intensity, preventing luminance saturation and improving signal-to-noise ratio, enabling quick and accurate spectral image capture without dimming the incident light, and can be economically implemented with a rolling shutter type CMOS sensor.
Implementation Method 1
a first sensor configured to receive a first image formed by light with a first wavelength, and a second sensor configured to receive a second image formed by light with a second wavelength
Data Source
AI summary
An apparatus includes a first sensor unit that includes a plurality of first sensors arranged in the first direction which include a first sensor configured to receive a first image formed by light with a first wavelength, a second sensor unit that includes a plurality of second sensors arranged in the first direction which include a second sensor configured to receive a second image formed by light with a second wavelength, and a controller configured to control the first and second sensor units. The controller controls the plurality of first sensors under a first common exposure condition, and controls the plurality of second sensors in the second sensor unit under a second common exposure condition.