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Introduction to Nanomechanics (Spring 2012). Martino Poggio. Nanomechanical Measurements. Displacement measurement is crucial for force transduction Different types of nanomechanical displacement measurements (advantages & disadvantages) Focus on optical interferometry
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Introduction to Nanomechanics(Spring 2012) Martino Poggio
Nanomechanical Measurements • Displacement measurement is crucial for force transduction • Different types of nanomechanical displacement measurements (advantages & disadvantages) • Focus on optical interferometry • Signal-to-noise ratio Introduction to Nanomechanics
Transduction vs. Sensing • A transducer receives energy from one system and transmits it to another, often in a different form. • A sensor responds to physical stimuli (e.g. heat, light, pressure, or motion) and generates an electronic signal for detection. Introduction to Nanomechanics
Mechanical Force Transducers F • Now we require a sensor for mechanical motion. x Introduction to Nanomechanics
Sensors for Mechanical Motion • Tunneling • Optical Deflection • Optical Interferometry • Microwave Interferometry • Magnetomotive • Piezoelectric • Capacitive Introduction to Nanomechanics
Displacement Measurements STM Detection Introduction to Nanomechanics
Displacement Measurements Laser deflection Introduction to Nanomechanics
Displacement Measurements Laser interferometry Fixed mirror “spring” x Pin “Movable” mirror Introduction to Nanomechanics
Displacement Measurements Laser interferometry Introduction to Nanomechanics
Displacement Measurements Laser interferometry LIGO – Gravitational Wave Detection Introduction to Nanomechanics
Displacement Measurements Laser interferometry Introduction to Nanomechanics
Displacement Measurements Microwave interferometry – capacitive detection K. L. Lehnert, JILA Introduction to Nanomechanics
Displacement Measurements K. L. Lehnert, JILA Introduction to Nanomechanics
Displacement Measurements Magnetomotive detection (via Faraday’s Law) Figure from K.L. Ekinci, Boston U. A. Cleland & M. Roukes, 1999. Introduction to Nanomechanics
Displacement Measurements Capacitive detection Introduction to Nanomechanics
Displacement Measurements Capacitive detection Introduction to Nanomechanics
Displacement Measurements Piezoelectric detection Introduction to Nanomechanics
Displacement Measurements Capacitive detection Introduction to Nanomechanics
e- 2DEG L QPC R 2DEG QPC as a mechanical displacement detector Introduction to Nanomechanics
10-12m / (Hz)1/2 100 10-21 10-1 10-22 10-2 10-23 10-3 10-24 10-4 10-25 10-5 4.50 4.75 5.00 5.25 Frequency (kHz) Displacement Measurements Measurement of Cantilever Thermal Noise at 4.2 K Spectral Density (A2 / Hz) Spectral Density (Å2 / Hz) Introduction to Nanomechanics