High-resolution imaging of biological cell with fiber-based composite interferometer

Abstract

We proposed and demonstrated an optical system for high-speed and high-resolution imaging of surface profiles. The system is a fiber-based composite interferometer in which a Michelson interferometer is used for the measurement of the surface profile of the sample and a Mach-Zehnder interferometer is used for compensation of phase deviation due to the systematic errors and environmental perturbations. In the system, a laser diode with wavelength of 531 nm was used as the light source. A two-axis translation stage was used for lateral scanning of the sample. In the reference arm, a reflection mirror was arranged on a translation stage driven by a piezoelectric transducer as the axial scanning component. The phase difference between the interferograms of both interferometers was acquired to obtain the surface height of the sample. The axial accuracy of ±5 nm was achieved where the imaging was acquired within one minute for a frame. The lateral resolution was at the diffraction limit of light. The system possesses the advantages of low cost, portability and flexibility. Furthermore, it can perform high-resolution imaging in large area without special shielding of the system as well as any special preparation of the sample.