Archive for February, 2009

Bouncing light beam redux

Monday, February 9th, 2009

Bouncing light beam. A long tank of water is presented sideways, with a laser beam entering the end on the right.  The laser is held by two rods and two clamps with three degrees of freedom.  The laser tube is below the tank, shooting up at a low angle from horizontal. The ...

When the buses are good.

Thursday, February 5th, 2009

I left work yesterday at 6 pm, and headed out to Mass. Ave. to catch the bus.  No hurry. The 96 bus pulled up and I hopped right on.  Bus pass means never waiting in the cold, at least until the bus routes diverge. The 96 caught all green lights, and pulled ...

Lens in and out of water

Monday, February 2nd, 2009

A ten gallon fish tank is illuminated on the side by a slide projector at a distance of six meters. The water contains a small amount of fluorescein, so a yellow cylinder of light spans the small faces of the tank.  A 15 cm lens held in the beam just outside ...