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Compact Interferometric Atomic Force Sensor

IP.com Disclosure Number: IPCOM000035658D
Original Publication Date: 1989-Jul-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Greschner, J: AUTHOR [+3]

Abstract

An atomic force microscope (AFM), as described by G. Binnig et al. in Phys . Rev . Letters, 56, 9, pp. 930-933 (March 1986), is combined with sensitive interferometric signal detection. The measurement head consists of a micromechanical Si lever 2 with a sharp end tip arranged in close proximity to the surface of sample 1. Lever 2 is firmly attached to the lower surface of a glass block 3 which contains beam splitter 3a for an optical beam 9 entering its top surface. The top surface of lever 2 and the neighboring surface area on the lower surface of glass block 3 are covered with metal layers 2a and 2b forming the plates of a capacitor to apply an electrostatic bending force to lever 2; layer 2b is provided with an opening in the optical path of optical beam 9.

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Compact Interferometric Atomic Force Sensor

An atomic force microscope (AFM), as described by G. Binnig et al. in Phys . Rev . Letters, 56, 9, pp. 930-933 (March 1986), is combined with sensitive interferometric signal detection. The measurement head consists of a micromechanical Si lever 2 with a sharp end tip arranged in close proximity to the surface of sample 1. Lever 2 is firmly attached to the lower surface of a glass block 3 which contains beam splitter 3a for an optical beam 9 entering its top surface. The top surface of lever 2 and the neighboring surface area on the lower surface of glass block 3 are covered with metal layers 2a and 2b forming the plates of a capacitor to apply an electrostatic bending force to lever 2; layer 2b is provided with an opening in the optical path of optical beam 9.

Laser 8 with a g/2 plate 7 and a polarizer P at its output generates a beam 9 with two orthogonal polarization directions M, R whose relative phase is changed in phase modulator 6 before the beam enters lens 5 and glass block 3; the latter acts as a Michelson interferometer for the two partial beams M, R, measurement beam M being reflected at lever 2 and reference beam R at mirror 3b. After reflection, beam R will have passed g/4 plate 3c twice such that its polarization direction coincides with that of beam M and both beams pass polarizer P before entering detector 4. The output signal of detector 4 is evaluated for the phase difference between beams M and R by...