Conclusion
We confirmed that a resonant frequency peak of a mirror on a mount that is similar to IFI STM 2 is around 120Hz.
Details
・Introduction
We conducted two experiments today.
・Displacement measurement of IFI STM 2's mount using LK-500
・Displacement measurement of a mirror and mirror mount similar to IFI STM 2's mount, conducted outside the vacuum chamber
・Displacement measurement of IFI STM 2's mount using LK-500
As reported in yesterday's Klog, we were unable to measure the displacement of IFI STM 2's mount using LV-9300A. Therefore, we re-conducted the displacement measurement using LK-500, which can measure displacement even with diffuse reflected light. To validate the measurement results, an accelerometer (TEAC-710) was attached on the LK-500's mount, and the coherence between the output signals of the accelerometer and LK-500 was measured.
During this experiment, we confirmed that the signal was within the dynamic range of the measurement instrument. Please refer to the first picture for the experimental setup. The results are shown in the second picture.
As a result, we were unable to measure the displacement. Despite applying external vibrations to the ground by shaking it with a shaker or tapping it manually, no signal was detected by the measurement device on time-domain data nor spectra, resulting in the failure of the experiment.
・Displacement measurement experiment using a mirror mount similar to IFI STM 2's mount, conducted outside the vacuum chamber
Due to the failure of the previous experiment, we conducted a measurement of the resonant frequency of a mirror and mirror mount with a structure similar to that of IFI STM 2.
Please refer to the fourth picture for the experimental setup. A resolution of LV-9300A is 0.15 nm. A distance between LV-9300A and a target is around 20 cm.
We measured several points of displacement. We mainly report the mirror displacement.
- Displacement measurement of the mirror plane displacement
A red point in the fourth picture is a measurement point. The result is fifth picture. We can confirm that a resonant peak is around 120Hz.
- Displacement measurement of the others points
We measured several points of displacement and upload all results in the sixth picture. We also attach pictures that show measurement points of each result.
Next
・Measuring a displacement of the mirror mount without the mirror and with shaking by hand or shaker.
・Measuring a displacement depending on how much necessary it is.
