Laser marking and engraving: Ensuring quality control with laser power measurement
Tuesday, June 18, 2019
Do you know how frequently the laser output power of your system typically changes during marking and engraving processes? Depending on the laser type, the maintenance needs and the environmental factors, the laser power consistency might not meet your expectations, which is a significant problem that impairs the quality of the marking and engraving processes.
Over the last two decades, a series of remarkable advancements in laser technology have refashioned the processing speed and efficiency of marking and engraving applications in the industry. The output power stability of the laser source, which varies depending on the laser type and architecture, is a vital parameter that determines the quality and consistency of the process. In almost all industrial lasers, short-term fluctuations due to thermal drift can be observed while you monitor the output power. Additionally, laser power might not be stable due to possible system maintenance needs or any other factors that may affect the laser power consistency over time.
For instance, the pulsed laser mode enabling high laser peak power is predominantly used in material processing applications. Moreover, diagnostic problems can deteriorate the pulse-to-pulse stability and subsequently cause power instabilities. In diode pumped systems, contrariwise, a change in the ambient temperature causes a shift in the central wavelength of the diode, which further leads to fluctuations or decrease in the output power. Such drawbacks may lower the yield and quality of your laser-based applications, this is especially true in the case of marking and engraving applications with tight laser output power tolerances.
Laser power monitoring is an instrumental step that facilitates the verification of the output power accuracy to ensure high-quality marking and engraving processes. The laser beam is focused on the material by using appropriate lenses and the beam position is generally adjusted with the help of positioning systems such as galvanometers. The penetration depth in marking and engraving applications is determined by the laser beam parameters on a material’s surface combined with the processing speed.
Particularly in material processing with tight laser output power tolerance, an intermittent output power monitoring can be performed at certain intervals by stopping your process for a short period. In this approach, the laser beam and detector can be positioned to complement each other, following this, the output power is measured by using the appropriate power detectors. In tightly focused beams, it is crucial to locate the power detector sensor out of the focus zone to prevent it from potential damage.
Laser power can also be monitored without interruption by placing the power detector out of the marking and engraving area but close to the beam. In this method, the reference power feedback reflecting from the material is determined and monitored during the process. Real-time recording of power data can also be realized for the inspection of long-term laser output power evolution by using state-of-the-art power detectors and monitors with statistics interface. In both laser power measurement approaches, the spectral range, sensitivity and response time of a power detector and its monitor play instrumental roles in the measurement of accuracy and repeatability.
So now you know that your laser source for your engraving and marking applications might not be stable over time and underestimated power fluctuations might cause unexpected results, as well as expenses. It’s important to not only ensure the quality of your throughputs, but also to take precautions in advance of potential laser source-based problems.