Astronomy 512 -- Spring 2006 -- Assignment 6 -- Due Tuesday May 2

  1. The output amplifier for the Triplespec HAWAII-2 array is illustrated below (in the dashed box in the lower right of the diagram; blown up with jumper options in the solid box in the upper right). This amplifier provides a buffer between the (wimpy) on-chip array circuitry and the outside world. Its voltage gain is close to 1.0 which may seem useless, but its strength lies in the ability to drive that signal through wires and into external circuitry with little or no influence on the input signal. The input transistor is a J270 JFET. These devices draw little or no current on their input gate (so they don't load their voltage sources).

  2. Use a laser to determine the groove spacing and blaze angle of the two diffractiong gratings that have been set out in the lab. Use the same technique to see if you can determine the physical density of the information stored on a CD vs. a DVD.