Line Scanner Variable Exposure CMOS Sensor Dynamic Range
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Solution Overview
Problem
Existing laser line probes have a limited dynamic range, making it difficult to accurately capture both bright and dark areas of an object's surface, which affects the precision of 3D coordinate measurement.
Innovation Solution
A laser line probe with a CMOS image sensor that uses a flexible rolling shutter approach to control exposure time row-by-row or column-by-column, allowing for non-sequential exposure and readout of the photosensitive array, thereby improving the dynamic range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a traditional photosensitive array with fixed exposure time is used, then the device structure is simple, but the dynamic range is limited and cannot accurately capture both bright and dark areas
Solution Approach 1:
The photosensitive array is divided into multiple independently controllable regions (e.g., first and second regions with different exposure times). This segmentation allows each region to capture light with optimized exposure parameters, enabling the system to simultaneously record both bright and dark areas with high precision without requiring complex global exposure adjustment mechanisms.
Solution Approach 2:
The exposure time of different regions of the photosensitive array is made dynamically adjustable rather than fixed. By varying exposure times across different regions, the system adapts to local lighting conditions, improving measurement precision in both bright and dark areas while maintaining a relatively simple overall device structure through localized control.
2Measurement precision
If a uniform exposure time is applied to the entire photosensitive array, then the control mechanism is simple, but the dynamic range is insufficient to capture both light and dark areas accurately
Solution Approach 1:
Different regions of the photosensitive array are assigned different exposure times based on local lighting conditions. Bright areas use shorter exposure times to avoid saturation, while dark areas use longer exposure times to capture sufficient light. This local quality approach improves image capture accuracy across the entire field of view without requiring a complex centralized control mechanism.
3Measurement precision
If the entire photosensitive array is exposed simultaneously with the same exposure time, then the readout process is simple, but the dynamic range is limited
Solution Approach 1:
The photosensitive array is segmented into multiple regions that can be exposed at different times. This segmentation enables the system to achieve a wider dynamic range by capturing both bright and dark areas with appropriately optimized exposure times, while the exposure control system remains relatively simple through localized timing adjustments rather than complex global coordination.
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 enhances the dynamic range of the imaging device, enabling more accurate imaging of both light and dark areas, leading to improved 3D coordinate measurement precision.
Implementation Method 1
each of the light sensors in the array of light sensors configured to convert an amount of optical energy captured by each of the light sensors into a digital signal value, the optical energy captured by the light sensors being from a reflected line of light from the surface of the object
Data Source
AI summary
A line scanner measures 3D coordinates of an object surface and includes a projector with a light source that projects a line of light at the object surface. The line scanner also has a camera with a 2D array of light sensors and electronics that controls the exposure and readout times of each light sensor, the exposure time being controlled in either rows or columns of the array in a non-sequential manner, the readout time being controlled in either rows or columns that are the same as the rows or columns whose exposure time is being controlled, each of the light sensors converts an amount of captured optical energy into a digital signal value, the captured optical energy being from a reflected line of light from the object surface. Further includes a processor that receives the digital signal values and calculates the 3D coordinates of the object surface.