The invention is a method and system for providing a standard interface between a client and a plurality of peripheral devices. As a sample solution is separated by centrifugal means, it is illuminated at a particular radial distance from the axis of rotation by a fine, preferably monochromatic, light beam. An acme-threaded rod passes through an acme nut mounted on each hub, one left hand threaded and one right hand threaded, such that the rod, when connected to a drive shaft and gear motor, and actuated causes the hubs to move toward each other to close the umbrella and away from each other to open the umbrella. The aperture-defining lens group includes at least one high-index lens made from a transparent high-index material having a refractive index nHI, where nHI>nSIO2 and where nSIO2 is the refractive index of silicon dioxide at the operating wavelength. The second layer is a single layer or a laminated body containing a light emitting substance. The reduction in time is attributed to the fact that CRRO can be computed by averaging position error signals over multiple tracks as opposed to total RRO which is computed by averaging over multiple revolutions on the same track.