Common path interferometer based on ball lens probe and silver coated mirror

A common path interferometer has been made with a ball lens packaged in a metal cylinder, silver coated mirror, and lucent type connector (LC) fiber patch cord. By simply placing mirror and a ball lens directly in front of a fiber patch cord, a compact and potentially disposable sensing probe for optical sensor could be implemented. A working distance of up to 1.6 mm and transverse resolution of 14 μm were achieved. With sensing probe, measurement of the refractive index was implemented.