Particle characterisation with a focus tuneable lens

A method of performing a dynamic or static light scattering measurement, comprising:

• illuminating the sample with a light beam, thereby producing scattered light by the interaction of the light beam with the sample;
• detecting scattered light along a detection optical path that intersects the light beam within the sample at a detection region, thereby obtaining data;
• adjusting at least one of a location of the detection region, a volume of the detection region, or an angle between the illumination and detection optical path at the detection region, by changing the focal length of a focus tuneable lens in at least one of the illumination and detection optical path,
• wherein a focusing reflector is configured to direct at least one of the illumination optical path into the sample and the detection optical path from the sample toward the detector;
• repeating, at least once, the step of detecting scattered light after performing at least one corresponding step of adjustment by changing the focal length of the focus tuneable lens;
• performing a static or dynamic light scattering measurement using the data obtained from at least one focal length of the focus tuneable lens.