Endoscopic CMOS Sensor Fixed Pattern Noise Cancellation
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Solution Overview
Problem
Conventional endoscopes with image sensors placed in handpieces are prone to misalignment and damage, limiting their use in capturing high-quality color and fluorescence images in light-deficient environments, and require multiple sensors for different spectral bands, making them bulky and unsuitable for distal tip placement.
Innovation Solution
An endoscopic imaging system with a CMOS image sensor placed at the distal end, using minimal area sensors and pulsing electromagnetic radiation to generate fluorescence imaging data, allowing for RGB and fluorescence data overlay in a single imaging session, and employing fixed pattern noise cancellation techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple sensors are used for different spectral bands, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent divides the spectral detection task into temporal segments by pulsing different spectral bands at different times. The sensor captures separate images for each spectral band (e.g., blue, green, red, fluorescence) during different time intervals, then combines them computationally. This segmentation in time replaces the need for multiple simultaneous sensors, reducing device complexity while maintaining measurement precision.
Solution Approach 2:
The patent employs periodic pulsing of different spectral bands to illuminate the scene sequentially. Each spectral band is activated in periodic cycles, allowing a single sensor to capture multiple spectral components over time. This periodic action enables one sensor to perform the work of multiple sensors, resolving the contradiction between measurement precision and device complexity.
2Ease of operation
If image sensor is placed in handpiece unit, then ease of operation is improved, but reliability deteriorates
Solution Approach 1:
The patent inverts the traditional endoscope architecture by placing the image sensor at the distal end (tip) of the endoscope rather than in the handpiece unit. This inversion allows the sensor to be positioned where it is most needed for imaging, eliminating the need for complex light transmission paths and improving reliability by removing the sensor from the vulnerable handpiece area.
Solution Approach 2:
The patent nests the image sensor within the constrained distal end of the endoscope. By integrating the sensor into the small distal tip area, the design achieves compact nesting that maintains ease of operation while improving reliability through fixed positioning at the distal end, eliminating alignment issues between separate handpiece and sensor components.
3Device complexity
If minimal area sensor is used, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent transitions from spatial differentiation (multiple sensors side-by-side) to temporal differentiation (single sensor at different times) to capture multiple spectral bands. This dimensional change from space to time allows a minimal area sensor to achieve the measurement precision of a larger multi-sensor array by accumulating spectral information sequentially.
Solution Approach 2:
The patent changes the operational parameters of the single sensor by varying the illumination spectral content over time and adjusting exposure settings for each spectral band. This parameter changes approach allows the minimal area sensor to optimize its measurement precision for each spectral component, compensating for its small physical area through intelligent parameter control.
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 high-definition imaging with reduced pixel counts, improved optical simplicity, and the ability to capture multiple data types in a single session, enhancing image quality and reducing the need for multiple sensors, thus fitting within the constrained distal end of an endoscope.
Implementation Method 1
Each of the plurality of pixels in the pixel array generates dark frame data when the emitter is not emitting electromagnetic radiation
Implementation Method 2
the electromagnetic emitter is configured to pulse a pattern of varying wavelengths of electromagnetic radiation... the pixel array generates fluorescence imaging data
Implementation Method 3
Exponential smoothing is applied to a series of dark exposure frames such that a reference frame is generated
Data Source
AI summary
Fluorescence imaging with reduced fixed pattern noise is disclosed. A method includes actuating an emitter to emit a plurality of pulses of electromagnetic radiation and sensing reflected electromagnetic radiation resulting from the plurality of pulses of electromagnetic radiation with a pixel array of an image sensor. The method includes reducing fixed pattern noise in an exposure frame by subtracting a reference frame from the exposure frame. The method is such that at least a portion of the plurality of pulses of electromagnetic radiation emitted by the emitter comprises electromagnetic radiation having a wavelength from about 795 nm to about 815 nm.