Laser-Wobble: Show amplitude spectral density instead

Calculations/Laser-Wobble/Laser-Wobble.md

@@ -87,7 +87,7 @@ print(f"Video processing took {processing_time:.2f} seconds ({processing_time /
     Snapshot capture of frame   2331 at  77.70s: Intensity 12.612
     Snapshot capture of frame   2664 at  88.80s: Intensity 12.257
     Snapshot capture of frame   2997 at  99.90s: Intensity 12.728
-    Video processing took 251.50 seconds (0.084 seconds per frame).
+    Video processing took 257.32 seconds (0.086 seconds per frame).
 
 
 
@@ -202,8 +202,11 @@ pass
 ```python
 from scipy import signal
 
-fx, psd_x = signal.periodogram(np.nan_to_num(laser_position[:, 1]), frame_rate)
-fy, psd_y = signal.periodogram(np.nan_to_num(laser_position[:, 0]), frame_rate)
+frequency_x, power_spectral_density_x = signal.periodogram(np.nan_to_num(laser_position[:, 1]), frame_rate)
+frequency_y, power_spectral_density_y = signal.periodogram(np.nan_to_num(laser_position[:, 0]), frame_rate)
+
+amplitude_spectral_density_x = np.sqrt(power_spectral_density_x)
+amplitude_spectral_density_y = np.sqrt(power_spectral_density_y)
 ```
 
 ## Spectral Analysis
@@ -214,15 +217,16 @@ The following figure looks at the spectral density in the displacement along X a
 fig, ax = plt.subplots(2, 1, figsize=(16, 8))
 
 ax[1].axvline(x=2.822, color="red")
-ax[1].annotate(" theoretical spring resonance", xy=(2.822, 2e5))
+ax[1].annotate(" theoretical spring resonance", xy=(2.822, 1080 / 2 - 150))
+
+ax[0].loglog(frequency_x, amplitude_spectral_density_x, label="X axis")
+ax[1].loglog(frequency_y, amplitude_spectral_density_y, label="Y axis")
 
-ax[0].loglog(fx, psd_x, label="X axis")
-ax[1].loglog(fy, psd_y, label="Y axis")
 for a in ax:
     a.set_xlabel("frequency / Hz")
-    a.set_ylabel("spectral density")
+    a.set_ylabel("amplitude spectral density")
     a.set_xlim(0.5, 15)
-    a.set_ylim(1, 5e5)
+    a.set_ylim(1, 1080 / 2)
     a.legend()
     a.grid(axis="x", which="both")
     a.grid(axis="y", which="major")