Calculating Phase Noise from the D2-135
Q: What is the phase-noise on my laser beat-note going to look like when locked with the D2-135 Offset Phase Lock Servo (OPLS)? A: There are a lot factors that affect the final lock performance of the D2-135. Like frequency noise, phase noise is measured in terms of a noise density — or noise within a frequency band: dBc/Hz. The “Hz” tells us the width of the frequency band is 1 Hz. The “c” in dBc is for “carrier” as dBc is the ratio of the power of the phase noise relative to the carrier. The density of noise will [...]
Introduction to Servos Part I
What is Servoing? The goal of a servo is to adjust some output to keep an input at a constant value (typically 0). Think about how the cruise control feature on a car works: the cruise control adjusts the gas throttle (the servo’s output) in order to keep the speedometer reading (the servo’s input) a specific value. The servo accomplishes this goal by feedback: if the speed is too low, the servo gives the car more gas and the car speeds up and visa versa. Even though the speed of the car is a function of many variables (the amount [...]
Introduction to Servos Part II
Time-dependent Servoing Coming Soon…
