Spectrometric Device With Split-Exposure Regions for High Dynamic Range
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Solution Overview
Problem
The dynamic range of photodetectors is limited, preventing the acquisition of spectra with both high and low intensity light using a single detector, as high intensity light saturates the detector while low intensity light falls below the noise level.
Innovation Solution
A spectroscopic measurement apparatus and method using a photodetector with divided regions for different exposure times to capture high and low intensity light, combining spectrum data from these regions to achieve a high dynamic range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single photodetector is used to acquire the spectrum of measurement target light, then the device complexity is reduced, but the measurement precision deteriorates because the photodetector cannot simultaneously detect both high-intensity and low-intensity light within its limited dynamic range
Solution Approach 1:
The light receiving surface of the photodetector is divided into a first region and a second region, each capable of independent exposure time control. The first region uses a first exposure time to detect high-intensity light without saturation, while the second region uses a second exposure time to detect low-intensity light with sufficient signal-to-noise ratio. This segmentation allows a single photodetector to effectively handle a wide dynamic range spectrum.
Solution Approach 2:
The exposure times for the first and second regions are made different and adjustable, allowing the system to dynamically adapt to varying light intensities across different wavelength bands. The analysis unit selectively combines data from regions with appropriate exposure times based on the specific spectral characteristics being measured.
2Measurement precision
If the exposure time is increased to detect low-intensity light, then the measurement precision of low-intensity light improves, but the high-intensity light causes saturation in the photodetector
Solution Approach 1:
The light receiving surface is divided into multiple regions with different exposure time capabilities. The first region is optimized for detecting high-intensity light with a shorter exposure time to avoid saturation, while the second region uses a longer exposure time to detect low-intensity light with adequate signal-to-noise ratio.
Solution Approach 2:
Different regions of the photodetector are assigned different exposure time characteristics tailored to their specific detection needs. The first region operates with exposure parameters optimized for high-intensity signals, while the second region uses parameters optimized for low-intensity signals, allowing each region to function in its optimal performance range.
3Object-generated harmful factors
If the exposure time is decreased to avoid photodetector saturation from high-intensity light, then the device can handle high-intensity light, but the low-intensity light falls below the noise level and cannot be detected
Solution Approach 1:
The photodetector's light receiving surface is divided into multiple regions that can operate with different exposure times simultaneously. This allows the system to capture both high-intensity and low-intensity light components in the same spectral measurement without one compromising the other.
Solution Approach 2:
The solution adds the dimension of spatial differentiation on the photodetector surface, creating multiple detection zones with different temporal integration characteristics. This transforms a single-dimensional exposure time parameter into a multi-dimensional detection capability across different spatial regions.
4Measurement precision
If two photodetectors with different exposure times are used to acquire high and low intensity light spectra, then the measurement precision improves, but the device complexity increases due to wavelength axis alignment and synchronization requirements
Solution Approach 1:
Multiple detection regions with different exposure time capabilities are merged into a single photodetector device. This integration eliminates the need for complex synchronization and wavelength axis alignment between separate detectors, while maintaining the benefits of multi-exposure-time detection.
Solution Approach 2:
A single photodetector is designed to perform multiple detection functions simultaneously by dividing its light receiving surface into regions with different exposure characteristics. This universal device can detect both high-intensity and low-intensity light within a single spectral acquisition, replacing the need for multiple specialized detectors.
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
Enables the acquisition of a spectrum with a high dynamic range using one photodetector, allowing simultaneous measurement of both high and low intensity light without saturation or noise interference.
Implementation Method 1
a photodetector (20) which receives the spectral image for a first exposure time by a plurality of pixels arranged on one or a plurality of rows in a first region on a light receiving surface to output first spectrum data of the measurement target light
Data Source
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AI summary
A spectroscopic measurement apparatus 1 includes an optical system 10, a photodetector 20, and an analysis unit 30. The optical system 10 guides measurement target light from an object S to a light receiving surface of the photodetector 20, and forms a spectral image of the measurement target light on the light receiving surface of the photodetector 20. The photodetector 20 includes the light receiving surface on which a plurality of pixels are arranged respectively on a plurality of rows. The photodetector 20 receives the spectral image for a first exposure time by a plurality of pixels arranged on one or a plurality of rows in a first region on the light receiving surface, and outputs first spectrum data of the measurement target light. The photodetector 20 receives the spectral image for a second exposure time by a plurality of pixels arranged on one or a plurality of rows in a second region on the light receiving surface, and outputs second spectrum data of the measurement target light. The second exposure time is longer than the first exposure time. Thus, a spectroscopic measurement apparatus and a spectroscopic measurement method that can acquire a spectrum of light with a high dynamic range using one photodetector are realized.