A centrifugal separator includes a separation barrel having a central axis, an upper end, a lower end, a bottom, and an interior wall that is an axially-extending cylindrical surface of rotation. In particular, a unitary laser diode of the invention provides a light receiving area overlying a semiconductor substrate to correspond to a radiation area of light emitted from a laser diode so as to reduce chip size in respect to a conventional one while maintaining a monitoring current identical to the conventional one as well as improve heat-radiating features. That water shower of thin cold air intercepting screen is sprayed toward about the neck and the shoulders to the flanks of the bather. In one aspect, when users authenticate themselves to a server, the server returns a short-term supply of one-time-passwords or account numbers for use in secure access and financial transactions on other systems.