Experimental investigation of ghost imaging of reflective objects with different surface roughness

We present an experimental demonstration of ghost imaging of reflective objects with different surface roughness.The influence of the surface roughness, the transverse size of the test detector, and the reflective angle on the signal-to-noise ratio(SNR) is analyzed by measuring the second-order correlation of the light field based on classical statistical optics. It is shown that the SNR decreases with an increment of the surface roughness and the detector's transverse size or a decrease of the reflective angle. Additionally, the comparative studies between the rough object and the smooth one under the same conditions are also discussed.

Compact long-working-distance laser-diode-based photoacoustic microscopy with a reflective objective

Photoacoustic microscopy(PAM) has quickly developed into a noninvasive biomedical imaging technique to achieve detection, diagnosis, and monitoring.Compared with Q-switched neodymium-doped yttrium aluminum garnet or optical parametric oscillator lasers, a low-cost and small-size laser diode(LD) used as an alternative light source is conducive to achieving the miniaturization and integration for preclinical transformation.However, the LD’s low peak output power needs the high numerical aperture objective to attain tight focus, which limits the working distance(WD) of the system in only2–3 mm, resulting in not achieving the backward coaxial confocal mode.Here, we present a compact visible LD-based PAM system with a reflective objective to achieve a 22 mm long WD and a 10 μm lateral resolution.Different depth subcutaneous microvascular networks in label-free mouse ears have successfully reappeared in vivo with a signal-to-noise ratio up to14 d B by a confocal alignment.It will be a promising tool to develop into a handy tool for subcutaneous blood vessel imaging.