Gravitational lens simulator
Specify the parameters below and hit Submit. The result will be a 128x128 grid with the lensed image of a source at the specified position plotted in yellow contours. The source is indicated by a red dot and the galaxy (fixed at (64,64) on the grid) by a green dot. If requested, the caustics are plotted in blue and the Fermat surfaces in purple. You can obtain help on any parameter by clicking on its name.