Why Measuring Laser Performance Is Vital for Micromachining

In the world of medical device manufacturing, precision isn’t just a goal—it’s a mandate. From catheter components to micro-sized implants, flawless processing is required. At the heart of many of these manufacturing processes lies a powerful tool: the laser. But even the most advanced laser systems are only as reliable as the measurements used to monitor their performance. Laser performance is not just a technical necessity; it’s a strategic imperative for manufacturers committed to quality and precision.

The Role of Lasers

Lasers have become indispensable in medical device production due to their ability to deliver high precision, minimal thermal impact, and repeatable results. Applications range from cutting and drilling micro-sized features in catheters to marking serial numbers for traceability. Their ability to interact cleanly with materials like polymers, metals, and ceramics makes them ideal for producing intricate components that meet stringent regulatory standards.

But this precision comes with a caveat: laser systems are physical and electronic components that degrade over time. Without consistent measurement and monitoring, even minor shifts in performance can lead to defective parts, compromised safety, and regulatory non-compliance.

Why Measurement Matters

Laser engineers are accustomed to hearing that the success of any laser system really depends on a laser that performs consistently. In medical device manufacturing, this consistency is non-negotiable. A slight drift in laser power or beam size can mean the difference between a clean cut and a failed product.

Frequent measurement of the laser in the process ensures the success of the overall process as well as several other factors. First is process repeatability, which is essential for producing identical parts across thousands of units. Second is regulatory compliance, as medical devices must meet strict FDA and ISO standards. Third is cost efficiency, where early detection of performance issues prevents costly rework and scrap. Fourth is patient safety, since devices must function as intended without risk of failure due to manufacturing defects.

Key Performance Indicators

To maintain consistency, manufacturers must monitor key performance indicators (KPIs).

Output power: Measured anywhere from milliwatts to kilowatts, output power quantifies the amount of light the laser delivers to the material. In medical applications, where materials are often delicate, precise control of power is critical. For example, a gradual drop in power during the process can result in incomplete cuts and scrapped parts.

Beam size and geometry: The beam’s diameter and shape at the worksite affect how energy is distributed. When applying the laser, it is critical that the beam size remains consistent during the process so the laser performs as engineered for the application. Beam profiling tools help visualize and quantify these parameters.

Power density: Usually defined as “watts per square centimeter,” power density combines output power and beam size to express how intensely the laser interacts with the material. It’s a high-level indicator of process effectiveness. Changes in either power or beam size can drastically alter power density, impacting weld or cut quality and repeatability.

Pulse characteristics: For pulsed lasers, pulse width, shape, and frequency are vital to measure and understand. These parameters influence how the laser interacts with the material over time. In drilling applications, for example, pulse frequency affects hole depth and cleanliness.

Focus position (Z-axis): Focus shift due to thermal effects or component wear can move the laser’s focal point away from the intended location when unintentional absorption of laser light happens in laser components. This affects beam size at the work site and will result in exponential drops in power density, causing the laser to perform adversely.

Beam alignment (X-Y position): In micromachining, even a few microns of misalignment can result in defective parts. Monitoring beam position ensures the laser hits the exact spot intended.

Unique Challenges 

Medical device manufacturing presents unique challenges that make measurement even more critical. First, because the parts require micro-scale precision, with components often measured in microns, there is usually very little room for error. Second, because of material sensitivity, where polymers and exotic metals are used, especially when thicknesses are small, parts can be easily damaged by excess heat or energy. Third, parts often involve complex geometries. Devices may require intricate cuts, holes, or markings that demand consistent beam behavior. Fourth, processes usually involve high-volume production, where repeatability across thousands of units is essential. Finally, because of environments where regulatory bodies oversee processes, strict documentation is required, resulting in detailed records of manufacturing parameters, including laser performance.

Without robust measurement protocols, manufacturers risk producing parts that fail inspection—or worse, fail in the field.

Measurement Tools 

Since there is a need to better understand laser performance in medical device manufacturing and advances in instrumentation technology, measuring and analyzing these KPIs is easier than ever before. There are many useful tools available to those who need to collect this information.

Power and energy sensors: The use of a power meter system—a combination of sensor and display—has become commonplace in the medical device arena. Thermopile sensors measure continuous-wave or average power over time. Pyroelectric sensors are used to capture pulse-to-pulse energy on repetitive pulse lasers. These sensors are paired with handheld meters or PC interfaces to record, analyze, store, and present data. In some cases, these systems are integrated directly into manufacturing systems for continuous monitoring.

Beam profilers: These systems capture beam size and shape data where the laser is doing its work, along with what the laser is doing at and around the focused spot, using an imager to make the invisible laser light visible. The image is then analyzed for a wide variety of measurements by software running on a local PC connected to the imager. Optical systems, usually fixed to the imager, will be used to optimize both the laser power and the laser size reaching the imager. 

Fast photodiodes: These devices, coupled with an oscilloscope, capture and verify pulse width, shape, and frequency in real time. These are often essential for verifying that pulsed lasers operate within programmed parameters on repetitive pulse lasers.

Stand-alone and integrated systems: Different operational scenarios may require power measurement and/or beam profiling systems to be integrated into the process for frequent measurements. Some sensors are built into manufacturing cells, providing real-time feedback and enabling automated adjustments. In other cases, a stand-alone system can be set up on the system when it is not in use to measure these parameters. Either way, these tools provide a more complete picture of the laser’s behavior at the worksite. By capturing both the numerator (power) and denominator (beam size) of the power density equation, engineers can ensure the laser is delivering energy precisely and consistently.

Common Causes of Performance Drift

Regardless of the process and the environment, even stable laser sources can experience performance drift for different reasons. In some cases, contaminated, faulty, or aged optics can cause problems. Dust or debris can absorb laser energy, reducing output power. Thermal effects can often result from compromised optics. Heat buildup can shift the focus point or alter beam shape. Also, environmental factors play a role where vibration, humidity, and temperature changes affect alignment and stability.

Best Practices for Measurement

To maintain laser performance in medical device manufacturing, consider the following best practices. 

Measure at the worksite: Always capture data where the laser interacts with the material, not just at the source. Some products will provide real-time feedback on part of the laser system, which can be useful. However, it doesn’t measure the entire system, including where laser problems likely happen.

Monitor over time: Establish baseline measurements and track changes to detect drift early. Measure a new system frequently to better understand how the system may change over time. Then, take less frequent measurements over time to ensure overall system stability.

Use appropriate sensors: Match the sensor type to the laser’s characteristics and the information that you need to capture. Rely on trusted resources, like a company’s field sales engineer, to select the correct equipment for your application, your system, and your use.

Calibrate regularly: Ensure sensors and meters are calibrated to maintain accuracy. Power and energy measurement systems will usually require a roughly 12-month recalibration. Often, this is required in medical device manufacturing. 

Establish good documentation practices: Maintain detailed records for compliance and troubleshooting. Anticipate problems that may arise with your laser system so you can return it to an as-new condition when conducting preventative or corrective maintenance.

Measurement Enables Mastery

Medical device manufacturers operate in a high-stakes environment where quality, safety, and precision are paramount. Lasers offer unmatched capabilities, but only when their performance is measured and maintained. Measurement of the performance is crucial to verifying and ensuring its consistency. By investing in robust measurement tools and protocols, manufacturers can ensure consistent product quality meets regulatory requirements, reducing downtime and waste, protecting patient safety, and ultimately extending the life of their laser systems.

In short, measurement isn’t just a technical task—it’s a strategic advantage. For medical device manufacturers committed to excellence, it’s the key to unlocking the full potential of laser technology.

John McCauley is principal sales territory manager and high power laser application specialist for MKS Ophir, with a focus on medical, automotive, and directed energy applications. From 2009 to 2016, he served as the company’s Midwest regional sales manager and product specialist for all markets. Since 1998, his background has been as an end user of, and an applications engineer working with, laser marking and engraving systems. He has also worked closely with several mid-Indiana metal fabricating customers. He can be reached at [email protected].