Philip H. Jones, Onofrio M. Maragò & Giovanni Volpe
Fig. 9.15 — Noise tests
Noise tests. (a) Dark spectrum: the power spectrum recorded with the diode in total darkness is a measure of the electronic noise level. The spike at 50 Hz is caused by the power supply. All values are a factor of 103 to 105 below the optically trapped particle spectrum (grey spectrum). (b) Light spectrum: the power spectrum recorded with the trap’s laser light impinging directly onto the photodiode with no microsphere in the trap is a measure of the stability of the set-up. The low-frequency noise is most likely caused by the presence of mechanical instabilities in the set-up.