A Scientist’s Warning: The Longer B1 40W, and the Critical Truth About Class IV Laser Safety

We live in a remarkable time for creation. In workshops and garages around the world, desktop machines are performing feats once reserved for industrial factories. I recently came across a prime example of this revolution: the Longer B1 40W, a laser engraver that boasts the ability to slice through 20-millimeter-thick plywood in a single pass. As a materials scientist, I was impressed. This is the kind of power that truly changes what an individual creator can achieve.

But as I delved into the specifications, my admiration was punctured by a sharp sense of unease. On the machine’s popular retail page, I found a small, seemingly innocuous detail in its description: “laser class ii.” This detail, this tiny label, was a jarring contradiction to everything I knew about physics and laser safety. It was a contradiction that, if misunderstood, could have dangerous consequences. This isn’t just a product review; it’s the conversation we must have when immense power becomes this accessible.

How Do You Fit an Industrial Engine into a Desktop Body?

First, let’s appreciate the engineering that makes such performance possible. The B1 40W’s heart is its 48,000mW (a true 44-48W) optical power output. This isn’t achieved through a single, massive laser source. Instead, it’s a marvel of optical engineering called Beam Combining.

Imagine eight powerful, separate streams of water. Individually, they are strong. But if you could use a series of precisely angled channels to merge them all into one single, high-pressure jet, the result would be immensely more powerful. This is, in essence, what the B1 40W does with light. It takes the output from eight individual 6W diode lasers and, using a sophisticated array of lenses, combines them into one intensely concentrated beam. A key part of this process involves Fast Axis Collimation (FAC) lenses, which essentially tame the unruly nature of each laser’s light, making it more orderly and vastly easier to focus into a tiny, energy-dense spot.

The result is scientifically sound and genuinely impressive. This is why it can vaporize wood and mark steel with such authority. This power is real. And it is the fundamental reason we must treat this machine with the utmost respect.

A Glimpse of the Sublime: Painting on Steel with Physics

This immense power doesn’t just destroy; it can create with breathtaking subtlety. One of the most fascinating capabilities of the B1 40W is engraving colorful patterns onto stainless steel. This isn’t done with pigment or ink. It is, quite literally, painting with physics.

The principle at work is called Thin-Film Interference. You’ve seen it in the swirling, rainbow colors on a soap bubble or a drop of oil on wet pavement. The color comes from light waves bouncing off the top and bottom surfaces of a microscopically thin layer. Depending on the layer’s thickness, certain colors (wavelengths) of light cancel each other out, while others are reinforced, producing the color we see.

When the B1 40W’s laser strikes the steel, its intense, controlled heat grows a transparent oxide layer on the surface. By modulating the power and speed with incredible precision, the machine controls the thickness of this layer down to the nanometer. A slightly thicker layer will produce a different color. It’s like sculpting a rainbow on a nanoscale canvas. This ability to manipulate matter with such finesse is a beautiful testament to the laser’s power. It’s also a stark reminder of the energy we are handling.

The Conversation We Must Have: A Tale of Two Laser Classes

Now we arrive at the heart of the matter—the reason I felt compelled to write this. The “Class II” label is not just an error; it’s a dangerously misleading one. According to the international safety standard IEC 60825-1, and confirmed by the machine’s own detailed user manual, the Longer B1 40W is unequivocally a Class IV laser.

Let’s be perfectly clear about what this means.

• Class II lasers are very low-power devices, like a grocery store barcode scanner. They are considered safe because your natural blink reflex is fast enough to prevent eye damage from a brief, accidental exposure.

• Class IV lasers are at the opposite end of the spectrum. They are high-power devices with the potential to cause immediate and severe injury. The hazards are multiple:

  1. Direct Eye Hazard: A direct or reflected look into the beam, even for a fraction of a second, can cause permanent blindness.
  2. Scattered Radiation Hazard: This is the most misunderstood danger. The bright point of light where the laser hits the material is itself a laser light source, scattering energy in all directions. Looking at this “dot” without proper protection is like looking at a miniature sun; it is also extremely dangerous to your eyes.
  3. Skin Hazard: The beam can cause serious burns to the skin.
  4. Fire Hazard: The laser can easily ignite flammable materials in the work area.

To mistake a Class IV laser for a Class II is like mistaking a professional chainsaw for a butter knife because they both have handles. The consequences of underestimating the tool are dire. Operating this machine requires adopting a professional safety mindset. The provided safety glasses, which are specifically rated to filter the 450-460nm wavelength of this laser, are not a suggestion; they are a non-negotiable piece of personal protective equipment (PPE) for anyone in the vicinity of the operating machine. A well-ventilated space and a readily accessible fire extinguisher are equally essential.

The Machine’s Intelligent Reflexes

To its credit, Longer has equipped the B1 40W with a suite of “intelligent reflexes”—a nervous system designed to mitigate some of these risks. It includes a flame sensor that will halt a job and sound an alarm, and a gyroscopic sensor that stops the laser if the machine is bumped or tilted. The automated air assist is another part of this system, intelligently controlled by software commands (M8 for on, M9 for off) to blow away smoke and suppress flare-ups, resulting in cleaner and safer cuts.

These features are brilliantly engineered. They are like the advanced safety systems in a modern car—traction control, automatic braking, airbags. They can and will save you from a bad situation. But they are no substitute for an alert, knowledgeable, and responsible driver. Your brain remains the most important safety feature.

The Creator’s Pact

The Longer B1 40W is a testament to how far technology has come. It places truly formidable power onto the desktops of creators everywhere. But it is not merely a product you buy; it is a pact you enter into.

The machine offers you its incredible power to cut, to shape, and to create art from pure physics. In return, it demands your unwavering respect for that power. It demands your knowledge of its risks and your diligence in mitigating them. True creativity, the kind that endures, is not born from the reckless application of force, but from the masterful and responsible command of it.

So, by all means, be thrilled by the possibilities this tool unlocks. But before you press “start” for the first time, take a moment. Read the manual. Check your safety glasses. Clear your workspace. Understand the pact. With your eyes wide open to both its phenomenal potential and its profound risks, you are finally ready to create.