Characterization of an amplified piezoelectric actuator for multiple-reference optical coherence tomography

The characterization of an amplified piezoelectric actuator (APA) as a new axial scanning method for multiple-reference optical coherence tomography (MR-OCT) is described. MR-OCT is a compact optical imaging device based on a recirculating reference-arm-scanning optical delay using a partial mirror that can enhance the imaging depth range by more than 10 times the reference mirror's scanning amplitude. The scanning amplitude of the used APA was varied between 30 μm and 250 μm, depending on the scanning frequency of between 0.8 kHz and 1.2 kHz. A silver-coated miniature mirror was attached to the APA via ultraviolet-cured optical adhesive, and the light source was a super-luminescent diode with 1310 nm center wavelength and 56 nm bandwidth. The sensitivity was measured with and without the partial mirror in the reference delay line as a function of scan speed, frequency, and range, therefore providing results for MR-OCT and TD-OCT modes. It was found that the APA provides more than twice the mechanical scanning range compared to other opto-mechanic actuators, but results indicate degradation of signal-to-noise ratio and sensitivity at larger imaging depths. In conjunction with MR-OCT, the scan range of maximum 200 μm can be enhanced up to 1-1.5 mm by using a reduced amount of orders of reflections, which could be of interest to increase sensitivity in the future.