This "invisible" mark can only be viewed when tilted at the correct incident angle in a well- lit environment

Marked area when viewed at normal conditions

Need to mark text or identifying information on acrylic parts without detracting from the look of the piece? If so, follow the steps below to create a mark that is invisible unless viewed at the correct incident angle.

For this demonstration, we used a SYNRAD 10W CO2 laser, FH Series marking head (with a 200 mm focusing lens), and WinMark Pro software. After creating two lines of stroke text (Simple font), we identified the following mark parameters:

Set Velocity to 15 inches per second.

Set Power to 10% (the goal is to mark with approximately 1.5 Watts of power. On this particular laser that corresponded to a duty cycle percentage was 10%.

Set Resolution to 750.

Set Text Height (on the Format tab) to 0.165 inches.

We also adjusted Pline delay values to minimize hot spots at the beginning and end of line segments. For this example, we set Pline Start Delay to 100, Pline End Delay to 550, Interseg Delay to 0, and Off Vector Delay to 300.

All other mark parameters were left at their default values. At these settings, we marked the 25-character text string in 0.48 seconds. As the photos illustrate, the text is not noticeable until carefully inspected at the proper angle.