EPJ Techn Instrum (2020) 7: 2
https://doi.org/10.1140/epjti/s40485-020-0053-9

Research Article -

Optical excitation of atomic force microscopy cantilever for accurate spectroscopic measurements

¹ Department of Physics, McGill University, 3600 rue University, H3A 2T8, Montreal, Canada
² Department of Physics, Texas State University, 601 University Drive, 78666, San Marcos, USA
³ Departamento de Fisica, Universidad San Francisco de Quito, Diego de Robles S/N, 170901, Quito, Ecuador

^a yoichi.miyahara@txstate.edu

Received: 31 October 2019
Accepted: 27 January 2020
Published online: 10 February 2020

Abstract

Reliable operation of frequency modulation mode atomic force microscopy (FM-AFM) depends on a clean resonance of an AFM cantilever. It is recognized that the spurious mechanical resonances which originate from various mechanical components in the microscope body are excited by a piezoelectric elemen that is intended for exciting the AFM cantilever oscillation and these spurious resonance modes cause the serious undesirable signal artifacts in both frequency shift and dissipation signals. We present an experimental setup to excite only the oscillation of the AFM cantilever in a fiber-optic interferometer system using optical excitation force. While the optical excitation force is provided by a separate laser light source with a different wavelength (excitation laser : λ=1310 nm), the excitation laser light is still guided through the same single-mode optical fiber that guides the laser light (detection laser : λ=1550 nm) used for the interferometric detection of the cantilever deflection. We present the details of the instrumentation and its performance. This setup allows us to eliminate the problems associated with the spurious mechanical resonances such as the apparent dissipation signal and the inaccuracy in the resonance frequency measurement.