Everything you want to know about light, and probably a little bit more!

http://www.oceanopticsbook.info/

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# Tag: Geometry

## Ocean Optics by Curtis Mobley

## Online Triangle Calculator

Everything you want to know about light, and probably a little bit more!

http://www.oceanopticsbook.info/

This is a triangle calculator.

Specifically, this is the open source triangle-calculator provided here:

https://ostermiller.org/calc/triangle.html

Since an LED emits light roughly in the shape of a cone, we can use triangle math to predict the amount of area an LED in a particular installation will light up.

After the calculator has *any* three parts (not only the ones I entered) of the triangle, it will calculate the rest of the parts.

In the calculator pictured, I’ve entered the three values that are depicted in green – the calculator figured out the rest.

For this example, I know:

- I have 90° lenses
- I have to cover a 20″+ diameter of surface area

**I need to know how high to mount the fixture to get 20″ in diameter of coverage**.

Here’s how I filled out the calculator:

- Divide the 90º lens by two to get
**angle 1**: 90° / 2 =**45**° - The light is perpendicular to the water, so
**angle 2**is**90**° - Divide the diameter by two for the radius you need to cover, for
**side 1**: 20″ / 2 =**10**“

**From this, the calculator tells us (side 2) that the light should be mounted 10″ above the water.**

Here’s a simple diagram I created based on some similar calculations: