Optical Proof of Principle

The optical proof of principle will demonstrate the refractive properties of a glass prism, whose refractive index depends on the wavelength of light. The test will demonstrate the optical equipment mounting mechanisms which are adopted for this design, as well as the effectiveness of the prism to separate different colored LED’s.

The mounting system involves equally sized blocks of wood. To mount the lens, a rubber wheel of the same diameter is used to surround the lens. A slot is then cut out of a block of wood with a width slightly smaller than that of the wheel. The flexible rubber is then forced inside this slot, where it holds firmly. The metal sheet with a small hole in it is mounted inside a narrow slit made in a different block of wood. The prism is rested on top of two blocks of wood. The height of the lens is not critical. The diodes to be testes are taped using electrical tape to blocks of wood. The blocks of wood were chosen such that the diodes are lined up almost at the optical plane. Slight bending of the diode contacts is needed for fine adjustments. Finally, a box with a white paper is used as the image screen.

All of the above modules are movable on the table, and so experimentation with different spatial dimensions is very easy. Once all the locations are chosen, the modules will be fastened to one large board using deck screws. The diodes need to be interchangeable, and so they cannot be fastened permanently. For the proof of principle test the diodes will be placed in location by hand, but for the final design they will have a designated fixed grove, where they can be placed a secured temporarily.

Once all the modules are aligned in the arrangement outlined in the final design report, the four diodes will shine through the small hole, from where the beam will be collimated towards the prism, and collected on the image screen. Pencil will be used to mark down the location of each LED beam on the screen. If the different colors end up far enough apart to be distinguishable, then we will consider the optical system to be successful.

During preliminary tests, we were able to get the spot sizes to be ~0.5-1cm apart, which will be distinguishable by the movable diode whose active area is less than that.