Accurate positioning and focusing are essential for consistent laser engraving results. This guide covers the key steps for using red-light preview effectively, calibrating its alignment with the actual engraving area, and identifying common issues that may affect positioning and focus.
1. Overview
1.1 What Is Red-Light Preview?
Red-light preview projects the outline of an engraving design onto the workpiece before processing. It provides a visual reference for checking the approximate engraving position and graphic size, helping you confirm the intended marking area before starting the actual engraving.
Important: The red light is an auxiliary indicator and positioning reference, not the actual processing laser. Red-light preview can help with positioning and provide a focusing reference, but it cannot replace actual test engraving.
2. How to Enable Red-Light Preview
The following procedure applies to LightBurn-type laser marking software. The exact interface may vary depending on the software version and machine configuration.
Step 1: Enable the Red-Light Output Port
Enable the red-light output port in the software or device settings.
Step 2: Create and Select the Engraving Design
Create the design you want to engrave in the software and select the graphic.
Step 3: Start Red-Light Preview
Click Frame in the software toolbar.
Step 4: Check the Projected Outline
The red light will project the outline of the selected design onto the workpiece. Use the projected outline to check whether the engraving position and approximate size are suitable before starting the actual engraving process.
3. Red-Light Preview Calibration
3.1 Why Calibrate the Red-Light Preview?
If the projected red-light outline does not align with the actual engraving result, the red-light system may require position and size calibration. Proper calibration helps ensure that the preview more accurately represents the actual engraving area.
3.2 Calibration Procedure
Step 1: Create a Reference Design
Create the em-smart reference graphic in the software and center it within the workspace.
Step 2: Perform an Actual Test Engraving
Engrave the reference graphic on the workpiece. This actual engraving result will be used as the reference for calibrating the red-light preview.
Step 3: Compare the Red-Light Outline with the Engraving Result
Turn on red-light preview and compare the projected red-light outline with the actual engraved graphic.
Step 4: Open the Red-Light Settings
Go to Device Settings → Galvo and Basic Settings → Red Dot
Step 5: Adjust the Red-Light Position and Scale
Adjust the X Offset, Y Offset, X Scale, and Y Scale in small increments. Repeat the preview and comparison process until the red-light outline aligns with the actual engraving result, then save the settings.
| Parameter | Adjustment | Result |
|---|---|---|
| X Offset | Increase | Moves the red-light outline to the right |
| X Offset | Decrease | Moves the red-light outline to the left |
| Y Offset | Increase | Moves the red-light outline upward |
| Y Offset | Decrease | Moves the red-light outline downward |
| X Scale | Increase | Increases the graphic size along the X-axis |
| X Scale | Decrease | Decreases the graphic size along the X-axis |
| Y Scale | Increase | Increases the graphic size along the Y-axis |
| Y Scale | Decrease | Decreases the graphic size along the Y-axis |
After calibration, the red-light preview should closely match the actual engraving result in both position and size.
4. Common Mistakes and Important Safety Notes
4.1 Relying Only on the Red-Light Outline
Incorrect: Use the red-light outline as the only reference and start production without performing a test engraving.
Recommended: Treat the red light as a positioning reference and perform a first-piece test engraving before batch production.
4.2 Assuming Overlapping Red Dots Always Mean Perfect Focus
Incorrect: Assume that the two red-light spots overlapping means the machine is definitely at the optimal focal position.
Recommended: Overlapping red-light spots provide a focusing reference, but they do not always guarantee the actual optimal laser focus. For high-precision applications, use a gradient focus test to verify the focal position.
4.3 Assuming the Projected Size Is 100% Accurate
Incorrect: Assume that the projected red-light outline always represents the exact size of the engraving graphic.
Recommended: Calibrate the red-light scaling to ensure that the preview more accurately corresponds to the actual engraving dimensions.
4.4 Avoid Direct Exposure to the Red-Light Spot
Do not look directly into the red-light spot. Avoid unnecessary exposure to the light source and follow the safety instructions provided with your laser equipment.
4.5 Recalibrate After Equipment Maintenance or Impact
If the galvo scanner or field lens has been removed and reinstalled, or if the machine has experienced a significant impact, recalibrate the red-light system and verify the actual focal position before resuming production.
4.6 Special Considerations for Transparent and Highly Reflective Materials
Transparent or highly reflective workpieces may cause the red-light spots to shift due to reflected light. In these situations, dual red-light focusing may not provide a reliable reference. Use test engraving or a gradient focus test to determine the actual focal position instead.
