Ring-down Box

You can measure the finesse of a resonator with the ring-down box without locking the resonator!

1. super fast (see characterization)
2. without locking the resonator

Use this formula to analyse the datapoints:
y(x)=A*exp^(-x/t)+y0 with x:=time, t:= delay time

Afterwards calculate the finesse with F=2pi*t*FSR with FSR:=free spectral range.

• Electronic drawing (PDF-file)

Bilder rein mit dem Kurbven etc.

• Inverter: LT1363
  • Invert negativ input voltage to positiv
  • Datasheet_LT1363
  • Power supply: +/-5V
• Comparator: AD8561
  • Compare input voltage and threshold value
  • Datasheet_AD8561
  • Power supply: +/-5V
  • High speed timing: 7ns @ 5V
• Flip-Flop: SN74HC74
  • Output of trigger
  • Datasheet_SN74HC74
  • Power supply: +5V
  • High speed timing: 15ns

• 1x XLR connector
• 1x Power supply +/-5V
• 1x single switch
• 1x double switch
• 3x BNC connctors
• 1x Potentiometer
• 1x big red button
• 2x 8-pin holder
• 1x 14-pin holder
• 3x PSK 3-pin cables
• 5x 100n capacitors
• some resistors (3x 100k, 1x 4.7k, …)
• 1x Al-box
• 2x PCB´s