Camera calibration for Aurora 8

Camera calibration for Aurora 8

This calibration method applies to AURORA 8 machines shipped before October 17, 2023, and to machines that have a large error in camera accuracy after importing the calibration file;
For machines shipped after October 17, 2023, the camera has been calibrated and the camera calibration file has been saved to U-Disk.

Since the LightBurn software does not recognize the control card of the AURORA 8 PRO, the AURORA 8 PRO does not be calibrated.

How to load the camera calibration file 


Customers who need to use the camera function only need to import the corresponding camera calibration file according to the field lens. 

The AURORA 8 camera is calibrated at the factory.

Each type of field lens has a corresponding camera calibration file.
(Select the camera calibration file based on the text on the field lens.)

The camera calibration file is saved on the U-Disk that come with the machine.
Where you can find the calibration file of camera.
AURORA 8


AURORA 8 UV


How to calibrate the camera using LightBurn

Step 1: Print the calibration image
Print images on A4 paper; You can find the relevant image files in"Calibration file of camera" folder on the U-Disk that come with the machine.
If you still can't find it, please download it from the article attachment.

1. Select "lightburn Calibration Image.png", right-click, select Open with>> Photo


2. Select Print.



3. Choosing the right size.

Print Size Requirements:
AURORA 8 UV:
Field lens F=170(100mm) select 2 x 3 in.
Field lens F=254(150mm) select 3.5 x 5 in.
AURORA 8:
Field lens F=160(110mm) select 2 x 3 in.
Field lens F=220(150mm) select 3.5 x 5 in.
Field lens F=290(200mm) select 100 x 148 mm.
Attachment comes with three sizes of calibration image PDF files.

Step 2: Print Accuracy Verification Image
This validation accuracy image will be used in step 7.
1. Open Accuracy Verification File.
If your machine is an AURORA 8, please open “Fiber Marking Machine Accuracy Verification Image.PDF”
If your machine is an AURORA 8 UV, please open “UV Marking Machine Accuracy Verification Image.PDF”


2. Printing Verification Accuracy Images.


3. Select Print to Actual Size to print the actual object.


If you are printing a UV precision verification image, select Color for the Color option.


Step 3:Pre-calibration preparation
1.Place a white paper on the working platform to minimize calibration errors.


2. Press autofocus to achieve the correct focal length.


3. Adjusting the sharpness of the camera.
①Remove the cover.


②Turn on your computer's camera function.
(If the computer does not support the camera function, use the AMCAP2a please.
The AMCAP2a software can be found in "Calibration file of camera" folder on the U-disk that come with machine.


③Place a sheet of printer paper with text in the working platform.
The paper content should be in the smallest possible font. Arial font size 9 is recommended; the smaller the font, the smaller the error in adjusting the camera's sharpness.
If the image is clearly visible and does not need to be recalibrated for sharpness, please skip to step 4.
If it's not clear.


④ Unlock the fixing ring slightly counterclockwise.

⑤ Rotate the camera to adjust the sharpness.


⑥ Until the image is clearly visible.
Please don't use too large a font to adjust sharpness.


⑦ After making sure it is clearly visible, lock the fixing ring clockwise.


Step 4:Importing AURORA's field lens calibration files(.cor)
Each type of field lens has a corresponding calibration file.
The correct calibration file needs to be imported and then start the next step.
1. Select the field lens calibration file based on the text on the field lens.

Fiber lens:
f=160 mean 110mm field lens.
f=220 mean 150mm field lens.
f=290 mean 200mm field lens.

UV lens:
f=170 mean 100mm field lens.
f=254 mean 150mm field lens.

Finding the correct field lens correction file.
(You can find it under "Correction File" on the U-Disk that come with machine.)



2. Load the correct calibration file.

After loading the correct calibration file, the woring platform dimensions will be modified according to the parameters included in the calibration file.

After replacing the field lens with a new one, the calibration file (.cor) for the field lens also needs to be replaced.

Step 5: Calibrate the camera
1. Selection the camera.


2. Follow the prompts to place the calibration paper and capture the image.


Calibration requirements:
①Captured image score must be less than 1.0, and the smaller the score the better the calibration results.


②The degree of distortion of the captured image must be very small.
Ensures that the captured image is identical to the camera's live image.


③The captured image has distortion, you need to move the correction paper slightly and re-capture the picture until the distortion disappear.

Placement of calibration paper: Horizontal, either way is possible, as shown below.





Main center:


Bottom center:


Center left:


Center right:


Upper center:


Bottom right corner:


Bottom left corner:


Upper left corner:


Upper right corner:


Step 6: Alignment camera

1. Aligning the camera at the end of image capture.



2. Place a black card stock on the working platform and select the camera.
Select a black card stock that is similar in thickness to A4 paper.


3. Click on the Frame and start marking.
(Use the default values for the marking parameters.)




4. Proceed to the next step and follow the prompts to capture the image.


5. Double-click to mark the center of the four points and click Next.





6. Complete camera alignment.


Step 7:Verify accuracy after camera calibration
1. Place the printed image of inspection accuracy on the working platform.
Ensure that the Verification Accuracy image paper is placed flat on the platform, like below.
Verification of Fiber laser Inspection Accuracy Images:


Verification of UV laser Inspection Accuracy Images:


2. Select the corresponding camera and click Update Overlay to make the latest image appear on the canvas.


3. Click on "Tracks" to adjust thresholds.

Adjust the threshold until the purple circle encircles the black area, then box the portion that is unadulterated and the purple circle is intact.
Suitable thresholds:                                                                                                                  

Unsuitable thresholds:


Frame the image of 2*3 circles on the verified accuracy paper.


4. Set the corresponding marking parameters, and then start marking. 
(Fill graphics only on the paper pattern to avoid cutting through the paper.)
Suggested Marking Parameters:
AURORA 8 UV 5W:
Speed:1000mm/s;Frequency:50kHz;Q-Pulse:5μs;Interval:0.05mm
AURORA 8 20W:
Speed:1000mm/s;Frequency:50kHz;Power:50%;Interval:0.05mm
AURORA 8 50W:
Speed:1000mm/s;Frequency:50kHz;Power:40%;Interval:0.05mm

Parameters are available for reference and can be modified according to the actual situation.



Step 8:  Check for errors in the marking results
(Error range as close to 0mm as possible)
1. AURORA 8 Inspection Accuracy Standards: The marked circle covers the circle of the picture as much as possible, and the closer the error range is to 0mm, the better the camera is calibrated.
The error is less than 1mm, the result is qualified:

The error is greater than 1mm, the result is not qualified:

Qualified physical drawing:


2. AURORA 8 UV  Inspection Accuracy Standard: A marking circle exceeding the red area indicates a deviation of more than 1 mm, and exceeding the green area indicates a deviation of more than 2 mm. Experimentally derived marking machine error within 1mm indicates that the camera calibration effect is good, otherwise the need to re-calibrate the camera.
The error is less than 1mm, the result is qualified:

The error is greater than 1mm, the result is not qualified:

Qualified physical drawing:

The marking result is qualified, proceed to the next step.

Step 9:Exporting camera calibration files
Export the camera calibration file and save it to your computer.
If the calibration file is lost it can be re-imported.




END.

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