Underwater laser camera trap

Hi Guys,

I am completely new to Arduino and need some help with a thought of feasibility of the project. I am interested to use Arduino Uno to build an underwater camera trap. The problem is that I cannot use the "tripwire" concept using a laser and a reflector or light sensor on the other side. The idea is that an animal "breaks" the laser beam and triggers the camera.

I have been searching on the internet now for some time and came across some (but very few) possibilities and I am know down to two serious options.

Any thoughts and more ideas are more than welcome! Thank you!

Why "laser" instead of plain light? What kind of distances are you interested in?

Lasers are needed to prevent a decrease of intensity of normal light as it is absorbed quickly underwater.

Guido167:
Lasers are needed to prevent a decrease of intensity of normal light as it is absorbed quickly underwater.

This is why I was asking about the distances involved. If you're hoping to trigger an event from a fish coming within, say a foot, of your sensor, you could expect to see a difference in the light being reflected from a plain LED. Alternatively, you could detect it's shadow without providing any light source of your own.

KenF:
This is why I was asking about the distances involved. If you're hoping to trigger an event from a fish coming within, say a foot, of your sensor, you could expect to see a difference in the light being reflected from a plain LED. Alternatively, you could detect it's shadow without providing any light source of your own.

Thank you Ken, sorry I did not reply on the favorable distance. The favorable distance is more in the range of 10 to 40 meters, but that is also hugely dependent on water turbidity.
Just using the fact that approaching animals cast a shadow on light sensors is not going to work as this would not allow the camera trap to function at night. Furthermore, this would be highly dependent on the position of the incoming sunlight and the approaching direction of the animal.

10 - 40 meters away is quite a distance. Even a 2 meter long shark at that distance would be quite a small target. AND at night in turbid waters. The only technology I can think of that would have a chance would be some kind of sonar.

The favorable distance is more in the range of 10 to 40 meters, but that is also hugely dependent on water turbidity.

If you can't use the visible light spectrum to trigger the sensor, what are the chances you will be able to use a camera that uses the visible light spectrum, especially if the camera depends on reflected light for the photograph? In the range you describe, the water will need to be very clear.

Hi guys,
thank you for the feedback. The most important range is 0-10 m, whereas in seas like the Mediterranean I think a larger range is feasible. However, the question is if the technique with the laser sensor (option 1 in the opening post) actually works.

The advantage of lasers over normal light is the very narrow angle of divergence. This allows them to travel great distances without loosing too much intensity. Therefore a sensor placed a long way away, in the direct path of the laser, will still be able to detect a laser of very low power.

Once that laser hits a target, (such as a fish), it just becomes visible light like any other. Detecting it is a matter of detecting that dot in the scene. Image processing could be used to capture such a dot, but this is beyond the scope of the typical arduino.

Detecting a broken beam is relatively easy, detecting the reflected dot of a laser is a totally different story.

Guido167:
Hi guys,
thank you for the feedback. The most important range is 0-10 m, whereas in seas like the Mediterranean I think a larger range is feasible. However, the question is if the technique with the laser sensor (option 1 in the opening post) actually works.

The below has a lot of laser detector projects which might be of use to you.

https://www.google.com/search?num=100&lr=&as_qdr=all&q=arduino+laser+tripwire&oq=arduino+laser+trip&gs_l=serp.1.0.0i67j0j0i22i30.7098.9870.0.12038.5.5.0.0.0.0.137.513.3j2.5.0.msedr...0...1c.1.60.serp..0.5.500.VikAm5CiWik