Nanosecond vs picosecond lasers: what the terms mean

In descriptions of tattoo removal lasers we see the words nanosecond and picosecond, because the duration of the laser pulse is measured in exactly these units. So it is worth understanding what the terms really mean, in order to choose exactly the equipment you need (and to protect yourself from careless sellers).

In general, it is extremely hard to simply imagine how long a nanosecond lasts. Especially since, in popular usage, "nanotechnology" is the name given to everything that is not an adjustable wrench.

Let's picture the scale:

1 nanosecond = one billionth of a second, or

1 second divided by 1,000,000,000

Can you picture it? If it is still vague, here is the next, most vivid example:

Imagine that 1 nanosecond became an ordinary second — then 1 second would turn into 32 years! Yes, years! So 1 nanosecond relates to 1 ordinary second the way 1 second relates to 32 years.

What about picoseconds?

Picosecond lasers are already appearing, with pulses even shorter than those of nanosecond lasers. I will draw the same analogy as above.

Let's picture the scale:

1 picosecond = one trillionth of a second, or

1 second divided by 1,000,000,000,000

And now the scale in years. If 1 picosecond became 1 second, then 1 second would turn into 32,000 years!

Which lasers are the most common?

Among commercial laser models, the most common are sub-nanosecond lasers. That is, they are not true 1–2 picoseconds, but about 500–750 picoseconds. Compared with nanosecond lasers, this value is slightly less than 1 nanosecond: 750 picoseconds = 0.75 nanoseconds. This is close to 1 nanosecond but still not equal to it, hence the name sub-nanosecond lasers.

We are still waiting for truly picosecond lasers in the 10–100 picosecond range that would work in the same way as nanosecond ones.

The laser industry is growing, and femtosecond lasers are starting to appear in industry — and a femtosecond, as you can guess, is even shorter than a picosecond! So as not to get confused by the parameters, watch my next videos: I will explain why and how to read device descriptions, what the abbreviations ms, ns and ps mean, and why you will need them.