Light Path Simulator

Simulation Description

This web simulates the path of light from one or more laser in a custom medium. The simulation is based on Snell's Law, so reflection and intensity variation are not accounted for. In addition, the simulation is limited in a 2D space with a rectangular medium.

In this mockup version, the simulation doesn't work yet. The visualization given is just a placeholder.

How to Use

This application has two inputs:

• n(x,y): math expression
  The index of refraction of the medium, as a function of x and y. The expression should be parsable by JavaScript's eval() function, with x and y as variables. For example, "x^2 + y^2" or "Math.sin(x) * Math.cos(y)".
• Laser spec: side;position;angle;color
  The specification of the laser(s) to be simulated. Each laser is defined by its rectangle side hit (left (0), top (1)), position of incidence (normalized distance from the top left corner of the rectangle), angle relative to the normal of the sides (in degrees), and display color (in hex format). Multiple lasers can be specified by separating them with new lines.

This application has two outputs:

• Canvas
  Visual representation of the light paths inside and outside the medium. The rectangle itelf will be colored according to the index of refraction, with darker color representing higher index.
• Output Terminal
  Textual display of simulation status and results.

How It Works

The rectangle is split into a grid of cells. In this grid, the laser is treated as an object that occupies a single cell and have a direction of travel. In each iteration, the object has a probability of going either one step along the x axis or y axis with the probability proportional to the direction's components. Everytime the object moves by one cell, Snell's Law is applied. Using the the target and origin cell's index of refraction as well as the initial direction, the new direction after refraction is calculated. The interface of the refraction is taken to be the border between cells.

The simulation is run until all lasers exit the medium or a maximum number of iterations is reached. The position of each laser is tracked throughout the simulation and displayed on the canvas.