Techniques based on angle scanning reflectometry near the critical angle can provide high-resolution optical measurements and testing of transparent, absorbing, and turbid liquid samples. Until recently, such techniques were practical for laboratory instruments only. In this work we propose and analyze the design of a relatively simple, compact, and robust optical probe based on angle scanning reflectometry near the critical angle. The optical probe can be used as a high-resolution refractometer, permitting the measurement of the real and imaginary parts of the refractive index, or as an optical sensor to monitor physical and chemical processes in real time within complex liquids. The design offers easy handling, portability, and an adequate balance between size and stability. We study the optical characteristics of the instrument and present the results of an experimental prototype of the device.