Ring-down Box

Application of the ring-down box

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

Advantages

super fast (see characterization)

without locking the resonator

Measurement Method

Evaluation

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 setup

Explanation of the operating principle

Electronic drawing (PDF-file)

Bilder rein mit dem Kurbven etc.

Characterization

List of components

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