Reflective axicon based energy-efficient extended depth of focus quasi-Bessel beam probe for common-path optical...

This work presents an optical fiber negative/reflective axicon probe that generates an energy-efficient quasi-Bessel beam (QBB) having a central spot (CS) possessing ∼20% of the QBB power. With silver coating around the axicon, the CS power has been increased by ∼45%. The QBB possesses a large depth of field, ∼400µm, with a micron order spot size as obtained experimentally. The probe has further been explored for common-path optical coherence tomography. The probe length has been optimized to minimize the path length difference between the reference and sample signal. With a divergence angle of just 0.013°, the beam provides a lateral resolution of ∼2.5 to ∼16µm for an axial distance of 0.1 to 1.0 mm. The imaging results are presented for standard samples such as onion and Scotch tape.