Abstract: A housing contains a light source, a monochromator, a photosensitive unit and an oscilloscope-type display. A flexible bundle of fiber-optic elements extends from within the housing out, and is provided at its outer end with a spacing ring. The spacing ring is placed against a skin surface, holding the ends of the fiber-optical bundle properly spaced and oriented relative to the skin surface. At the other end of the bundle, the bundle is subdivided into one branch which receives light from the source, and another branch which emits light refleced from the skin surface into the monochromator. The monochromator projects the spectrum of the skin-reflected light onto the photosensitive unit. The output signal of the photosensitive unit, in a sequential and periodic manner, contains information concerning successive spectral components of the skin-reflected light. The sweep of the display is synchronized with this periodic sequence, so as to display a spectral analysis of the skin-reflected light.

Abstract: A resonator, including a radiation generator, mirrors located at either side of the radiation generator in the path of radiation emitted from the generator, and a coupling means are arranged to couple primary radiation of predetermined frequency into the resonator and extract secondary radiation therefrom at a frequency which is shifted with respect to the frequency of the primary radiation, the frequency shift arising due to parametric interaction of the primary radiation. In accordance with the invention, the coupling means includes dichroic mirrors located in the path of radiation of the optical resonator at an inclination with respect to the path and having the characteristic of being highly reflective for radiation of the wavelength of the primary radiation and highly transmissive to radiation of a wavelength of the secondary radiation.