In this article, we will explore the different powers of marking lasers and the pulse duration, focusing on wavelength. We will try to understand how these three parameters define the markings we make on components.
Laser markers can have either pulsed or continuous lasers. This is what we call the operating mode. With continuous-wave lasers, energy flow is constant. This means that the laser continuously emits a single, uninterrupted laser beam. The most common example of an uninterrupted laser beam is a laser pointer. Continuous-wave lasers are commonly used for laser cutting and laser welding.
With pulsed lasers, the laser beam is interrupted at regular intervals, allowing the energy to accumulate, reaching a higher peak power than continuous-wave lasers. The laser beam is released as pulses that last a certain amount of time, called the pulse duration. This high energy is required for many applications, such as laser marking.
Continuous-wave lasers may appear more powerful than pulsed lasers, but this is not always true. This is because, in reality, the power indicates the average laser power, and the average laser power of pulsed lasers is usually lower, even if the peaks are higher.
For example, a continuous 6,000 W laser continuously releases 6,000 W of laser power. On the other hand, a 100 W pulsed laser can release 10,000 W pulses each time.
Here, we will discuss the variable pulse duration version of the Fiber lasers, or LASIT’s FlyMOPA, which is ideal for marking plastic and all metal.
Pulsed lasers are subdivided into different categories based on the duration of their pulses. A modulator is used to control the number of pulses per second. Consequently, each pulse has a precise time length, called pulse duration, pulse length, or pulse width. The pulse duration is the time between the start and end of a pulse. There are different modulating methods to pulse laser beams. Q-switching, gain-switching, and mode-locking are a few examples. The shorter the pulse, the higher the energy peaks. These are the most common units used to express the pulse duration.
Milliseconds (one-thousandth of a second) are the longest time unit used to express the pulse duration and therefore have the lowest energy peaks. For example, the pulses of a hair removal laser can vary between 5 ms and 60 ms based on the thickness of the hair.
Microseconds (one-millionth of a second) are probably the most common pulse durations. They can be used for working materials. Microsecond lasers can be used for applications like spectroscopy and hair removal.
Nanoseconds (one-billionth of a second) are peak durations most commonly used in working materials, distance measurements, and remote detection applications.
Picoseconds (one-trillionth of a second) and femtoseconds (one-quadrillionth of a second) are the shortest pulse durations, a reason for which they are used for ultrashort laser pulses or ultrafast lasers. These lasers offer the most precise results and have areas subject to lower heat exposure. This prevents unwanted melting and allows for very precise engraving. They are used for processing materials in medicine (such as eye surgery), microscopy, measuring, and telecommunications. LASIT has developed its own picosecond laser, the FlyPico. It is highly effective for imperceptible marking, very dark black, and no reflection marking.
The MOPA laser marker is a fiber laser with a 1064 nm wavelength distinguished from traditional fiber lasers because it lets you control the pulse duration, which allows you to attain impossible results with traditional lasers, especially on plastic or color laser marking.
The Powermark FlyPico laser has a fiber source laser well known for its precision in black and imperceptible picosecond laser marking. It is the first choice when it comes to post-marking treatments, like citric or nitric passivation cycles.
The power of the laser affects its processing speed. Contrary to what many believe, the depth and bearing of the marking are independent of the laser wattage.
Below are a few examples of marking where the incisions were made with the same laser source with different powers. In this manner, it is clear how the power influences the speed of the laser marking process.
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