Patent ID: 8797528

Claim:
A flow cell assembly for use in a liquid sample analyzer, the liquid sample analyzer including a radiation source, a sensing device and a liquid sample source to supply a liquid sample, the flow cell assembly comprising: a liquid core waveguide including a cladding layer formed of a material having a lower refractive index than the liquid sample, wherein the cladding layer defines: an axially extending waveguide bore to receive the liquid sample, the waveguide bore having a bore input end and a bore output end; and an input opening at the bore input end; an input optical fiber having an optical fiber end face mounted at the input opening to transmit radiation from the radiation source into the waveguide bore, which radiation is transmitted through the waveguide bore and the liquid sample therein to the sensing device; and a nonresilient mask member interposed between the optical fiber end face and the input opening, the mask member defining an aperture through which light is transmitted from the optical fiber end face into the waveguide bore, wherein the mask member blocks light from the optical fiber end face not directed through the aperture.