Weekly Reports

Week 2: Sept 9-12

This week so far our group has decided on our preferred projects for the course as well as considered some of optics involved. Presently our group's first choice of project is the traffic monitoring system, with the free-space optical communication device as a second choice. We have also decided to use, at least as a testbed, a visible red laser pointer as a source and basic phototransistors as receivers. Examining the parts catalogs has shown that these components will be feasible in terms of cost and we intend to put in an order in lab next week unless there in a change in plans.

The general design for the traffic monitoring system at this point is to have two lasers on one side of the road, and two detectors on the other side. When a vehicle or pedestrian goes by a laser beam, the beam will not reach the detector. By having two sets of lasers and detectors, we can deduce the speed of the person/vehicle based on when each laser is blocked. We can deduce if it is a person or vehicle based on whether or not both lasers are ever blocked simultaneously. Our group discussed the possibility of minimizing the cost of the system by incorporating just one laser and one detector, and splitting the beam into two different intensities, sending them across the road at 2 different places using mirrors, and recombining them at the detector. The issue we had was that this was inherently unstable, with small changes in the positions of the mirrors misaligning the paths to the detector.