Through-the-Lens Laser Marking With Multi-Location Image Calibration
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Solution Overview
Problem
Laser marking systems face challenges in consistently marking larger workpieces due to limited camera field of view, leading to difficulties in recognizing and aligning workpieces, which results in increased setup time, operator training requirements, and potential misplacement or distortion of images, especially when workpieces are larger than the camera's field of view or are oriented improperly.
Innovation Solution
The system captures multiple images from different locations within the marking field and stitches them together to create a composite image, allowing for the identification and orientation of larger workpieces, and uses a through-the-lens camera arrangement to image workpieces directly from above, avoiding issues with external cameras that may cause shading and obstructions. This approach enables easy training of workpieces for run-time vision processing and reduces job setup time by allowing workpieces to be placed in any orientation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single camera field of view is used to capture the marking field, then the device complexity is reduced, but the manufacturing precision deteriorates due to inability to capture larger workpieces and maintain alignment accuracy
Solution Approach 1:
The marking field is divided into multiple image tiles captured at different locations. Each tile is individually corrected using calibration models specific to its location, and then stitched together to form a composite image. This segmentation approach allows accurate capture of large workpieces across the entire marking field while maintaining alignment precision.
2Manufacturing precision
If multiple image tiles are captured and stitched to form a composite image, then the manufacturing precision is improved for larger workpieces, but the loss of time increases due to additional image processing steps
Solution Approach 1:
Image calibration models are generated in advance at multiple locations across the marking field during a setup phase. These pre-computed calibration models store distortion and geometric correction data for each location. During actual workpiece marking, the system simply retrieves and applies the appropriate pre-generated calibration model, avoiding time-consuming real-time calibration computations.
3Area of stationary object
If external cameras are used to image workpieces, then the area of coverage is increased, but object-generated harmful factors increase due to shading and obstructions
Solution Approach 1:
A beam splitter or dichroic mirror is introduced as an intermediary optical element that allows the camera to capture light reflected from the workpiece surface without blocking the laser beam path. This intermediary enables the camera to image the workpiece from above through the same optical path as the laser, eliminating shading and obstruction issues while maintaining full field of view coverage.
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 solution allows for consistent marking of larger workpieces in any orientation, reducing setup time and improving alignment accuracy, while avoiding the limitations of external cameras and ensuring accurate image representation across the entire marking field.
Implementation Method 1
a laser, an image capture device, a marking head including electromagnetic energy deflectors and at least one lens, a beam path of the laser and a beam path of the image capture device both passing through the at least one lens
Implementation Method 2
a marking head including electromagnetic energy deflectors and at least one lens
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
A laser marking system includes a laser, an image capture device, a marking head including electromagnetic energy deflectors and a lens, beam paths of the laser of the image capture device both passing through the lens, and a computer system. The computer system is programmed to perform a method including generating an image calibration model at each of multiple areas across a marking field of the laser marking system, adjusting the electromagnetic energy deflectors to direct the beam path of the image capture device to multiple different locations within the marking field of the laser marking system, and capturing image tiles at each of the multiple different locations with the image capture device, wherein at each of the multiple different locations, if a location corresponds to an area at which an image calibration model was generated, correcting the image tile according to the image calibration model generated at the location.