Accurate red light alignment helps ensure that the preview position, actual laser marking area, and focus position of your fiber laser remain consistent.

This guide explains how to calibrate both the red light preview frame and the center focus indicator dot on em-smart Nova, Basic, and MOPA fiber laser marking machines.

Calibration may be required during initial machine setup, after replacing the galvo scanner or field lens, after optical components have been removed or adjusted, during routine maintenance, or during on-site machine inspection.

Important: The two procedures are different. Preview-frame calibration is performed in EZCAD and does not require opening the machine. Center red-dot calibration requires access to the galvo housing.

Calibrating the Red Light Preview Frame

The red light preview frame shows the approximate marking area before the laser starts engraving. If the red preview frame does not match the actual engraved position or size, it should be recalibrated.

When Should You Calibrate the Preview Frame?

You may need to perform this calibration if:

• The red preview frame is larger or smaller than the actual marked pattern.
• The red preview frame and the actual laser marking are in different positions.
• The alignment becomes inaccurate after replacing the field lens or moving the machine.

Tools required: black metal card, Phillips screwdriver, and 1 mm hex key.

Step 1: Create a Reference Square

Place a black metal card flat on the worktable. In EZCAD, left-click an empty area of the canvas so that no text or object is selected. Click Preview in the lower-left area of the software.

 

Two red dots will appear, and a pop-up message will indicate that the machine is in focusing mode.

Adjust the height control knob or handle until the two red dots overlap. This indicates the marking focus position.

Next, draw a square in EZCAD. A 30 mm × 30 mm square is recommended.

Step 2: Mark the Reference Square

Use the following parameters as the reference settings:

• Basic / Nova: Power 50%, Speed 500 mm/s
• MOPA: Power 50%, Frequency 48 kHz, Speed 500 mm/s

Start marking to engrave the solid reference square onto the metal card.

Do not move the metal card after marking. Its position must remain unchanged during the following calibration steps.

Step 3: Compare the Preview Frame with the Actual Marking

Activate the red light preview again. The machine will project a red rectangular frame onto the metal card.

Compare the red preview frame with the square that was actually engraved. There are two main types of misalignment:

• Position error: the red frame is shifted left, right, up, or down.
• Size error: the red frame is larger or smaller than the engraved square.
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EZCAD uses two groups of parameters to correct these differences:

• Red Light Offset X/Y: moves the entire preview frame horizontally or vertically.
• Red Light Scale X/Y: enlarges or reduces the preview frame.

Step 4: Adjust the Red Light Position

Press F3 on the keyboard to open the EZCAD parameter window. Locate Other → Red Light Pointer.

Adjust the Red Light Offset X and Red Light Offset Y values.

• Positive X: moves the frame to the right.
• Negative X: moves the frame to the left.
• Positive Y: moves the frame upward.
• Negative Y: moves the frame downward.

Change the value by only about ±0.1 at a time. Save the parameter, activate the preview again, and repeat the adjustment until the preview position is correctly aligned.

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Step 5: Adjust the Preview Frame Size

In the same F3 red light settings, adjust Red Light Scale X and Red Light Scale Y.

• A scale value greater than 1 enlarges the red preview frame.
• A scale value below 1 reduces the red preview frame.

Make very small adjustments of approximately 0.002 at a time. Save the parameters and activate the red light preview after each adjustment.

Continue until all four sides of the red preview frame approximately overlap the four sides of the engraved reference square.

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Step 6: Save Your Calibration Parameters

Once the preview frame is correctly aligned, save the configuration in the F3 parameter window.

We also recommend taking a screenshot of the final settings and backing up the parameter file. This makes it easier to restore the correct configuration if the computer or software is reinstalled.

Calibrating the Center Red Focus Indicator Dot

Unlike the preview-frame calibration above, this procedure requires opening the front section of the galvo housing.

You may need to perform this calibration if:

• The two red focus dots overlap, but the marking result is extremely weak or unclear.
• The two red dots cannot be made to overlap by adjusting the machine height.

Tools required: Phillips screwdriver, 1 mm hex key, and stainless steel plate.

Safety notice: Wear appropriate laser safety glasses when performing laser marking tests. Power off the machine before removing or reinstalling the galvo housing cover.

Step 1: Remove the Front Galvo Cover

Power off the machine. Use a Phillips screwdriver to remove the two fixing screws underneath the front cover.

Carefully remove the front cover from the lower gap and disconnect the white connector cable attached to the cover.

Step 2: Find the Correct Laser Focus

Power on the machine and open EZCAD. Place a stainless steel plate flat on the worktable. You may place a sheet of paper or a thin wooden board underneath the plate to prevent scratches.

Draw a square in EZCAD that fits completely within the stainless steel plate. In the original calibration example, a 110 × 110 mm square is used with a 200 × 200 mm stainless steel plate. If your plate is smaller, simply reduce the square size accordingly.

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Wear laser safety glasses. Set the power to 100% and enable continuous marking. Observe the laser reaction on the stainless steel while adjusting the height control.

According to the calibration procedure, the correct focus is indicated by a bright marking point, visible sparks, and a clear marking sound. If the marking reaction is weak or unclear, the focus position is incorrect.

For Nova, adjust the machine's height control. For Basic and MOPA models, use the column height adjustment handle to locate the correct focus position.

Important: Once the correct focus has been found, do not change the machine height, move the machine, or remove the stainless steel plate until the center red-dot calibration is complete.

Step 3: Identify the Small Red Dot

Left-click an empty area of the EZCAD canvas and click Preview. Two red dots will appear.

To identify the small red indicator dot, cover the lower opening with your hand. The red dot that disappears is the small red indicator dot.

Step 4: Align the Small Red Dot

Observe the position of the small red dot relative to the other red dot. The goal is to adjust the small red dot until the two dots completely overlap at the correct focus position.

Use the 1 mm hex key to adjust the two side screws shown on the red light assembly. These screws control the left/right position of the small red dot.

To adjust the vertical position, slightly loosen the two fixing screws on the red light holder with a Phillips screwdriver. Carefully move the holder upward or downward by hand, then retighten the screws after alignment.

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Step 5: Reassemble the Galvo Cover

After the two red dots are correctly aligned, tighten all adjustment screws.

Reconnect the front-cover cable and reinstall the galvo front cover securely.

The center red focus indicator calibration is now complete. You can return to normal height adjustment and material positioning.

Final Check

After completing the calibration, verify that the red preview frame corresponds to the actual marking area and that the two focus indicator dots overlap at the correct laser focus.

Keeping a backup of your EZCAD calibration parameters can make future maintenance, lens replacement, or software reinstallation much easier.