Developing an optical chopper-modulated capacitive probe for measuring surface charge

Ugolini, D.; McKinney, R.; Harry, G. M.
April 2007
Review of Scientific Instruments;Apr2007, Vol. 78 Issue 4, p043702
Academic Journal
Gravitational-wave observatories such as Laser Interferometer Gravitational-Wave Observatory (LIGO) use suspended optics in a Michelson interferometer configuration to measure strains in space between 10 Hz and 3 kHz. One potential noise source in this frequency range is the buildup and motion of surface charge on the optics, which can generate fluctuating electric fields, interfere with position control, and reduce reflectance by attracting dust to the optical surface. We have developed a capacitive probe to measure the magnitude and relaxation time of surface charge deposited on smaller test optics in high vacuum (∼10-5 Torr). Our device modulates capacitance with a tuning-fork optical chopper between probe and sample, chosen for vacuum compatibility and minimal cost. We have found that the probe has a resolution of (3.5±0.5)×105 e-/cm2 in air, on the order of charging levels that could contribute noise to Advanced LIGO, and sufficient for measuring relaxation times on test optics.


Related Articles

  • High Q factor bonding using natural resin for reduced thermal noise of test masses. Schediwy, S. W.; Gras, S.; Ju, L.; Blair, D. G. // Review of Scientific Instruments;Feb2005, Vol. 76 Issue 2, p026117 

    We show that a low acoustic loss resin enables composite mechanical structures to be bonded with minimal Q degradation. The resin is excreted from the Australian native grass tree Xanthorrhoea. This resin has traditionally been used as an adhesive by the Australian Aborigines. It is shown that...

  • Liquid Flow-Control Device. PIGMAN, WARD; HAYGOOD, J. D. // Journal of Dental Research;May1962, Vol. 41 Issue 3, p713 

    The article reports on a liquid flow control device. A device was engineered to make it easier to control slow rates of flow for liquids over significant periods of time which involves a wire fit inside a glass capillary tube where the length of the wire controls the rate of flow. Also used in...

  • Theoretical and experimental analysis of a linear accelerator endowed with single feed coupler with movable short-circuit. Forno, Massimo Dal; Craievich, Paolo; Penco, Giuseppe; Vescovo, Roberto // Review of Scientific Instruments;Nov2013, Vol. 84 Issue 11, p114701 

    The front-end injection systems of the FERMI@Elettra linac produce high brightness electron beams that define the performance of the Free Electron Laser. The photoinjector mainly consists of the radiofrequency (rf) gun and of two S-band rf structures which accelerate the beam. Accelerating...

  • High resolution kinetic energy by long time-delayed core-sampling photofragment translational spectroscopy. Li, Guosheng; Hwang, Hyun Jin; Jung, Hyun Chai // Review of Scientific Instruments;Feb2005, Vol. 76 Issue 2, p023105 

    A pulsed core-sampling photofragment translational spectroscopy (PTS) method with a long time-delay, which allows an extremely high kinetic energy resolution, is presented in this article. More commonly applying a short time delay between laser and pulsed acceleration electric field leads to a...

  • A Mach–Zehnder interferometer for the detection and noninvasive optical amplification of polarization rotation. LaForge, Joshua M.; Steeves, Geoffrey M. // Review of Scientific Instruments;Jun2008, Vol. 79 Issue 6, p063106 

    We present the theory and design of a Mach–Zehnder interferometer with orthogonally polarized arms that passively, noninvasively, optically amplifies polarization rotation in one arm of the interferometer. Theoretical analysis of the electric fields in the two arms is used to compare the...

  • Multifunctional microscope for far-field and tip-enhanced Raman spectroscopy. Vannier, Christophe; Boon-Siang Yeo; Melanson, Jeremy; Zenobi, Renato // Review of Scientific Instruments;Feb2006, Vol. 77 Issue 2, p023104 

    The development of a versatile and easy-to-use instrument designed for Raman micro- and nanospectroscopy in the visible range is described in this work. An atomic force microscope, an inverted confocal microscope, and a piezostage are combined to perform an accurate and fast tip-laser alignment...

  • Design of a high precision falling-ball viscometer. Brizard, M.; Megharfi, M.; Mahé, E.; Verdier, C. // Review of Scientific Instruments;Feb2005, Vol. 76 Issue 2, p025109 

    The increase in uncertainty throughout the viscosity scale being the principal disadvantage of capillary viscometry, an absolute falling-ball viscometer has been developed, making it possible to cover a wide range of viscosities while keeping a weak uncertainty. The measurement of viscosity of a...

  • The archiving system of the Virgo antenna for gravitational wave detection Barone, Fabrizio; Garufi, Fabio; Milano, Leopoldo; Mours, Benoit // Review of Scientific Instruments;Oct97, Vol. 68 Issue 10, p3907 

    Describes the hardware and software architecture of the prototypes of the archiving system of the very long base line interferometric Virgo antenna for gravitational wave detection. Characteristics which make the system interesting and innovative; Testing of the prototype in the data...

  • NEW INSTRUMENTS. Stern, Joshua // Review of Scientific Instruments;Apr97, Vol. 68 Issue 4, p1910 

    Features scientific instruments and apparatus used in research. Mass-flow controller; Spectrometry flash system; Cryogenic cooler; Mechanical testers; Pulse generator; Micromechanical test instrument; Gas cell; Flame chamber; Thermal conductivity analyzer; Biochemical analyzer.


Read the Article


Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics