I set up a Michelson Interferometer with a 17 inch Schnupp Asymmetry to test the noie from the flexure mount. A 750 mm focal length lens is added 6 inches away from the long arm end mirror so that the beams are approximately the same size at the beam splitter. The visability is approximately 50% without alignment to maximize this.
Before the input port, I added a 10:90 (R:T) BS and photodiode to act as a power reference. When the laser's frequency is modulated, the power is also modulated. By dividing the Michelson output power by this reference power, the direct frequency dependence can be seen. This will allow us to put the Michelson on a midfringe and to test the noise from the flexure mount.
[Sander, Torrey, Daniel]
We modulated the laser using the DC Current Modulation Port, which changes the wavelength and power of the laser. Using this setup, we drove the Michelson through a fringe (wavelength change = lambda^2/(2*Schnupp Asymmetry) = 3 pm) with only a 2% change in power of the laser. We were able to lock the Michelson to a midfringe using the Moku laser lock box. We then looked at the Michelson output while playing a sound to see if there was a resonance in the flexure mirror mount, specifically around 500 Hz. We did not notice any resonance while playing a broadband white noise source like we did in the output filter cavity. We also did not notice any resonances when playing specific frequencies.