Particle characterization

1. A particle characterization apparatus comprising:

first body part, a second body part, a light source, a sample cell and a detector; wherein:

the light source is operable to illuminate a sample comprising dispersed particles within the sample cell with a light beam along a light beam axis so as to produce scattered light by interactions of the light beam with the sample;

the sample cell comprises a first wall and a second wall, each of the first wall and second wall comprising an internal surface arranged to be in contact with the sample and an opposite external surface, the first and second wall being arranged so that the light beam axis passes through the external surface of the first wall, then through the internal surface of the first wall, then through the sample, then through the internal surface of the second wall, then through the external surface of the second wall;

the light source is fixed to the first body part and the first body part is configured to engage with the first wall;

the detector is fixed to the second body part and the second body part is configured to engage with the second wall;

the first body part is separable from the second body part to enable access to the internal surface of each of the first wall and second wall for cleaning.

2. The particle characterization apparatus of claim 1 , wherein the detector is configured to provide an output that is suitable for determining a particle size distribution.

3. The particle characterization apparatus of claim 2 , wherein the detector comprises a plurality of detectors, each arranged to receive light scattered at a different range of scattering angles.

4. The particle characterization apparatus of claim 1 , wherein the apparatus comprises an instrument main body that is configured to split into the first body part and the second body part.

5. The particle characterization apparatus of claim 1 , wherein the first and second wall of the sample cell are separable.

6. The particle characterization apparatus of claim 1 , wherein the first and second body parts can be separated without detaching the light source from the first body part, and without detaching the detector from the second body part.

7. The particle characterization apparatus of claim 1 , wherein the first and/or second wall comprise a plano-convex lens, the respective external surface being a convex surface of the lens and the respective internal surface being a planar surface of the lens.

8. The particle characterization apparatus of claim 1 wherein the first body part comprises a first mount that directly engages with the first wall.

9. The particle characterization apparatus of claim 1 wherein the second body part comprises a second mount that directly engages with the second wall.

10. The particle characterization apparatus of claim 1 wherein the first mount and/or the second mount engages only with the external surface of the respective first and/or second wall.

11. The particle characterization apparatus of claim 1 , wherein the first mount and/or the second mount is configured to have only three points of engagement with the external surface of the respective first and/or second wall.

12. The particle characterization apparatus of claim 1 , wherein the first mount and/or second mount are configured to engage with the respective first and/or second wall only via spherical bearing surfaces of the respective mount.

13. The particle characterization apparatus of claim 1 , wherein the first body part and second body part together further comprise a third mount, by which the first body part is engageable with the second body part in a kinematically determinant manner.

14. The particle characterization apparatus of claim 1 , wherein the apparatus comprises a first base portion for standing the assembled apparatus on a planar surface with the first light beam axis substantially normal to the planar support surface.

15. The particle characterization apparatus of claim 1 , wherein one of the first body part and the second body part comprises the first base portion, and the other of the first body part and the second body part comprises a second base portion for standing the respective body part on a planar surface when the first body part is separated from the second body part.

16. The particle characterization apparatus of claim 1 , further comprising a seal element, configured to engage with the internal surfaces of the first and second walls when the first body part is engaged with the second body part, to contain sample between the first and second walls.

17. The particle characterization apparatus of claim 1 , wherein the external surface of the first and/or second wall are spherical.

18. The particle characterization apparatus of claim 1 , wherein the external surface of each of the first and second wall are spherical, and the centre of curvature of the respective external surfaces of the first and second walls are offset when the apparatus is assembled with the first wall engaged by the first body part, the second wall engaged by the second body part, and the first body part engaged with the second body part.

19. The particle characterization apparatus of claim 1 , further comprising a first housing part attached to the first body part, the first housing containing the light source, and a second housing part attached to the second body part, the second housing part containing the detector.

20. The particle characterization apparatus of claim 1 , wherein the first housing and first wall form a dust proof enclosure when the first wall is engaged with the first body part, and/or the second housing and second wall form a dust proof enclosure when the second wall is engaged with the second body part.