FTMW Electronics

Pictured to the left are the various electronic gadgets responsible for the spectrometer operation. From the top we have:
  • an oscilloscope (used for tracking the position of the cavity modes so as we can move the mirrors to achieve resonance at a particular frequency).
  • On top of the scope is a pressure gauge for the sample handling manifold.
  • To the right of the scope is the analog-digital converter that is connected to the computer.
  • Below this is the mirror box which controls the positioning of the mirrors. The mirrors are moved (via software commands) by a small stepper motor connected to one of the mirrors.
  • Below the mirror control box is the master oscillator, a Hewlett Packard 8671 frequency synthesizer. This is responsible for generating the polarizing microwave radiation as well as providing a 10MHz reference signal that allows synchronization of all other electronic equipment.
  • Next is the pressure gauge - the chamber pressure shown on the right hand gauge is about 2 ×10-7 torr (indicating the diffusion pumps are working fine!)
  • Next comes the all important timing box. This is responsible for making sure that everything fires in the correct sequence. It controls the sequencing of the gas pulse, microwave pulse, when the switch to the detector is opened and so on. Incorrect timing could lead to poor signal quality or even possible damage to the electronics.
  • Next comes the local oscillator which provides a radiofrequency signal that is used in the detection process to mix the microwave frequencies (of the molecular emission signal, typically several GHz) down to radiofrequency (~2.5MHz).
  • Under the local oscillator is the heater control box for controlling the heated nozzle.
  • Next is the Iota One valve controller. This controls the General Valve solenoid valve and is connected to the computer so that the various valve settings can be changed in the operating software.
  • Finally, the box at the bottom supplies power to the microwave circuit.