A spectrometer apparatus for measuring spectra of a liquid sample using an integrating cavity

In order to allow measurement of the extinction and absorption spectrum of a liquid sample such as a beverage such as wine, using a single apparatus and without movement of the liquid sample, a spectrometer apparatus 1 is provided comprises an integrating cavity 3 comprising a reflective inner wall or walls 5, configured to receive a cuvette 7 containing the liquid sample within the integrating cavity 5. A combination of light inlet ports P1, P2 and light outlet ports P3, P4 are provided to receive light from at least one light source 9 and to deliver light to a spectrometer 11. A light path adjuster 13, 13B is configured to selectively adjust a light path through the integrating cavity 5 such that at least two distinct light paths are provided; wherein when the light path adjuster 13, 13B is in a first configuration, the spectrometer apparatus 1 is in a transmission mode in which light from the light source follows a first light path 15 from the or one of the light inlet port(s) to the liquid sample such that the light from the light source irradiates the liquid sample directly before the light transmitted by the liquid sample is transmitted through the or one of the light outlet port(s) and received by the spectrometer 11 for wavelength analysis of the light to provide an extinction spectrum of the liquid sample without movement of the liquid sample; and when the light path adjuster 13, 13B is in a second configuration, the spectrometer apparatus is in a diffusely reflecting mode in which light from the light source follows a second light path 17 from the or one of the light inlet port(s) into the integrating cavity, is incident onto the reflective inner wall or walls of the integrating cavity and is diffusely reflected within the integrating cavity, such that the light from the light source irradiates the liquid sample before being transmitted through the or one of the light outlet port(s) and received by the spectrometer 11 for wavelength analysis of the light to provide an absorbance spectrum of the liquid sample contained in the cuvette without movement of the liquid sample.