Can drones detect microplastics using lidar?

Microplastics have been getting a lot of attention lately because of how widespread they are and their impact on health.

Some researchers in Japan have developed a way to detect different types of plastics using lidar from a drone, with a resolution of 0.29mm.

“A drone with this lidar sensor could help track plastic pollution on land and in water, making cleanup efforts more effective,” said Toshihiro Somekawa, the lead researcher.

For more details, check out Lidar News - https://blog.lidarnews.com/raman-lidar-microplastic-detection/

Wouldn’t this technically be detecting macroplastics if it’s using a drone?

Caden said:
Wouldn’t this technically be detecting macroplastics if it’s using a drone?

They claim a resolution of 0.29mm from 6 meters away. Since microplastics are defined as anything under 5mm, this would still qualify as detecting microplastics.

@Yan
The article I skimmed didn’t mention ‘microplastics,’ just ‘plastic debris.’

Also, it’s not exactly ‘drone lidar’—the researchers made a combined green lidar and hyperspectral sensor. They mentioned it’s light enough to be mounted on a drone, but it doesn’t sound like they actually tested it that way.

And for those saying this isn’t practical, this is how research works. Scientists develop new tools, and it takes time before they’re refined for real-world use. Right now, the standard method is collecting samples manually and analyzing them in a lab. If a drone can take one scan from 6 meters up, that’s already a huge improvement.

@Yan
A 4mm piece of plastic isn’t exactly ‘micro,’ so this claim seems a bit of a stretch.

Lidar and marine environments? Not gonna work. The way light bends in water will make this unreliable.

Jay said:
Lidar and marine environments? Not gonna work. The way light bends in water will make this unreliable.

If satellite-based lidar is used for coastal mapping, why wouldn’t a drone-mounted sensor work too?

@Rowan
That’s not the same thing. Satellites work at a nearly straight angle, so light reflection isn’t as big of an issue. Drones, on the other hand, operate at different angles, meaning the lidar beam won’t hit the receiver properly due to how light bends at the air-water boundary. It’s apples and oranges.

@Jay
Didn’t mean to step on toes—just discussing. I work in hydrology, mostly with river lidar, so I was curious about how this applies to coastal mapping.

A lot of research is already being done on topo-bathymetry using UAV-mounted lidar. The accuracy isn’t perfect, but it’s usable for many applications. Does saltwater affect the results more than freshwater?

@Rowan
If you’ve worked in river mapping, you should already know that water surfaces reflect visible light.

Jay said:
@Rowan
If you’ve worked in river mapping, you should already know that water surfaces reflect visible light.

Sure, but when using green-wavelength lidar, some of the signal does reach the riverbed. Otherwise, bathymetric models wouldn’t be possible.

The point is that a portion of the energy makes it through, and green lidar is specifically used because it penetrates water better than infrared sensors.

@Rowan
And do you have any proof the Japanese team is using green lidar?

Jay said:
@Rowan
And do you have any proof the Japanese team is using green lidar?

I thought we were discussing whether drone-mounted lidar could work at all in water, not just this specific study.

But the article does say they’re using a 532nm wavelength, which is green, so that lines up with what’s typically used for water penetration.

Jay said:
Lidar and marine environments? Not gonna work. The way light bends in water will make this unreliable.

Yeah, I see your point.

So, it works from just 6 meters up? That’s below wave crests in open water, lower than most obstacles on rivers, and too low to avoid trees, kites, and infrastructure on beaches.

Unless they develop a way to sort out plastic from sand and other debris, this seems pretty limited in real-world use.

@Palmer
Hyperspectral sensors can already distinguish materials at very fine levels. We use them to tell different plant species apart and even analyze sand composition, so identifying plastic should be possible.

If the alternative is collecting random sand samples and analyzing them in a lab, then even scanning from 6 meters up is a big step forward. Also, they don’t say 6 meters is the maximum range—just that at 6 meters, the resolution is 0.29mm.

@Rowan
If you check the pictures in the article, the equipment looks huge and can only differentiate between two types of plastic in controlled conditions.

No mobility, no ability to separate different materials, and no clear path to making it practical. This seems more like a funding pitch than a real-world solution.

Sure, why not?

Since microplastics are literally everywhere, I guess the drone will never return a ‘clean’ reading. Haha.

Read the title and immediately thought ‘this sounds sketchy.’