Apparatus for optical inspection of small volumes of liquid sample and cuvettes therefor

An apparatus for optical interrogation of a sample comprising:

• a base;
• a channel in the base;
• a single optical source for an optical signal positioned in a first aperture in the base such that the base defines a single optical path from the single optical source;
• and
• a first detector positioned in a second aperture in the base to receive the optical signal scattered by a sample disposed in a cuvette in a linear array of cuvettes received by the apparatus, wherein the channel is adapted to receive the linear array of cuvettes, wherein both the channel and each cuvette in the linear array of cuvettes has a narrower, lower portion and a wider, upper portion, the wider, upper portion having a perimeter larger than the perimeter of the narrower, lower portion, and wherein the narrower, lower portion of the cuvettes and the wider, upper portion of the cuvettes each comprises a plurality of planar side walls, each side wall at an angle from an adjacent sidewall, the cuvette further comprising a tapered portion from the wider, upper portion to the lower, narrower portion, wherein the channel is adapted to receive the tapered portion and conform thereto, the apparatus further adapted to position a cuvette in the array of cuvettes so that the lower, narrower portion of the cuvette is suspended in the single optical path from the single optical source such that the first detector detects the optical signal transmitted from the first aperture and scattered by the sample only in the narrower, lower portion of the cuvette;
• and
• wherein the single optical source and first detector are at least partially disposed in apertures in the base, and wherein the linear array of cuvettes is advances through the channel.

A method for measuring a turbidity of a sample comprising:

• separating at least one linear array of cuvettes from a stack of linear arrays of cuvettes;
• providing the separated linear array of cuvettes to a nephelometric apparatus each cuvette in the linear array of cuvettes comprising a narrower, lower portion and a wider, upper portion the wider, upper portion having a perimeter larger than the perimeter of the narrower, lower portion such that the narrower, lower portion of a first cuvette will fit within the wider, upper portion of a second cuvette thereby permitting the first cuvette to be stacked onto the second cuvette, wherein the narrower lower portion and the wider upper portion each comprises a plurality of planar side walls, each side wall at an angle from an adjacent sidewall, the cuvette further comprising a tapered portion from the wider, upper portion to the narrower, lower portion the cuvette having a sample for inspection disposed in at least the narrower, lower portion;
• receiving the cuvette in a channel in a base, wherein the channel has a tapered portion and the channel conforms to the tapered portion and positions the cuvette such that a planar sidewall of the narrower, lower portion of the cuvette is positioned in an optical path defined by an aperture or series of apertures from a light source that emits light directed only into the narrower, lower portion of the cuvette through the aperture or the series of apertures;
• transmitting light from the light source through the aperture or the series of apertures along the optical path, wherein the optical path is a single optical path further defined by the base and through a planar sidewall of the narrower, lower portion of the cuvette and into the narrower, lower portion of the cuvette;
• detecting, using a scattered signal detector, an optical signal from the optical source scattered by contents in the lower portion of the cuvette, the scattered signal detector having a surface positioned in an aperture orthogonal to the aperture in which the light source is placed, wherein the detector surface is approximately parallel to the optical path from the optical source;
• and
• advancing the linear array of cuvettes to position another cuvette in the array of cuvettes in the optical path and detecting, using the scattered signal detector, the optical signal from the optical source scattered by contents in the narrower, lower portion of the another cuvette in the array of cuvettes, the scattered signal detector having a surface positioned in an aperture orthogonal to the aperture in which the light source is placed, wherein the detector surface is approximately parallel to the optical path from the optical source.