Day 1 Week 3

Published on: Mon Jun 20 2011

For the past few days I have been deep into my project on an optical Turing machine. My notebook is full of drawings of various component layouts to produce different effects, and I have been creating charts like this:

1    1    L
0    0    L

That means
Read a 1
Move one element left 
Write a 1.
Read a 0
Move one element left
Write a 0.

I've been putting together various combinations like this, and trying out different arrangements of elements. An element is one RWM chart for a 1/0 combination. I'm working on a google sketch-up model of an element. I think the RW components and the M component will be separable, so I can combine various RW instructions with different M instructions, making it easier to 'program' the computer.

This does mean my Turing machine operates differently than the idealized machine, of the infinite tape, read/write head and table of instructions. The table of instructions is really the core of my Turing machine. This means to change the program a different table of instructions needs to be assembled. Because of this I'm not sure if this machine is actually a Turing machine. It is more like Charles Babbage's difference engine.

While thinking of different elements for my Turing machine, I have been reading about optical elements in greater detail. It also occurred to me that instead of arranging mirrors to move the light around, I could use fiber optic cable to send light from one element to the next. To do this I need a single mode fiber, and putting together fiber optic cable is apparently quite a tricky skill to acquire. I also learned about neutral density filters. This could be useful for adjusting the intensity of the output.