Particle detection system implemented with an immersed optical system
Fluid-based particle detection exhibits improved light collection and image quality from a light collection system that uses immersed optics on a flow-through cell for collecting and detecting scattered light from particles carried by the fluid. The flow-through cell includes first and second body sections that are coupled to form a unitary article and have opposed interior surface portions configured to form opposed walls of a flow channel through which the fluid flows. First and second optical elements are associated with the respective first and second body sections. In certain embodiments, at least one of the first and second optical elements is an integral part of its associated body section. A lens element constructed as an integral part of the unitary flow-through cell eliminates additional interfaces or bonding joints that cause scattering and absorption of light.
1. In a particle detection system for detecting particles entrained in a fluid stream that flows along a flow axis, the particle detection system having a view volume in which a light beam propagating along a light propagation path transversely intersects the fluid stream such that entrained particles upon which the light beam is incident cause portions of the light beam to scatter from the view volume as scattered light components, at least some of the scattered light components propagating through a light collection lens system that has a light collection lens system axis and being incident on a light detector that produces a signal representing the intensity of the scattered light components propagating through the collection lens system and incident on the light detector, the improvement comprising:
a foxy-though cell including first and second body sections coupled to form a unitary article, the first and second body sections associated with respective first and second optical elements;
each of the first and second body sections having opposed interior surface portions configured to form opposed walls of a flow channel through which the fluid stream flows;
a pair of spacers positioned between and coupled to the first and second body sections, the spacers spaced apart from each other to define the opposed interior surface portions that form the opposed walls of the flow channel; and
the unitary flow-through cell sized for insertion into the particle detection system in an orientation that positions the first and second optical elements along the light collection lens system axis.
2. The particle detection system of claim 1 , in which the pair of spacers is formed of optically transparent material to function as ingress and egress windows of the view volume for the light beam.
3. The particle detection system of claim 2 , in which the light beam has a beam width and the light beam egress window has a window width, the beam width and the window width being substantially the same to illuminate the entire flow channel.
4. The particle detection system of claim 2 , in which the light beam has a beam width and the light beam egress window has a window width, the beam width being focused to a size that is smaller than the window width to enable higher intensity light detection of smaller particles entrained in the fluid stream.
5. The particle detection system of claim 1 , in which the first and second body sections and the pair of spacers are fused into an integral structure, the pair of spacers defining surface interfaces between the spacers and the first and second body sections without bonding material present.
6. The particle detection system of claim 1 , in which the second body section is positioned between the view volume and the light collection lens system when the unitary flow-through cell is inserted into the particle detection system.
7. The particle detection system of claim 6 , in which the first optical element is selected from a group consisting essentially of a transparent optical element, a lens, and a mirror.
8. The particle detection system of claim 6 , in which the second optical element is a lens.
9. In a particle detection system for detecting particles entrained in a fluid stream that flows along a flow axis, the particle detection system having a view volume in which a light beam propagating along a light propagation path transversely intersects the fluid stream such that entrained particles upon which the light beam is incident cause portions of the light beam to scatter from the view volume as scattered light components, at least some of the scattered light components propagating through a light collection lens system that has a light collection lens system axis and being incident on a light detector that produces a signal representing the intensity of the scattered light components propagating through the collection lens system and incident on the light detector, the improvement comprising:
a flow-though cell including first and second body sections coupled to form a unitary article, the first and second body sections associated with respective first and second optical elements one of which being an integral part of its associated body section;
each of the first and second body sections having interior surface portions configured to form opposed walls of a flow channel through which the fluid stream flows; and
a pair of spacers positioned between and coupled to the first and second body sections, the spacers spaced apart from each other to define the opposed interior surface portions that form the opposed walls of the flow channel.
10. The particle detection system of claim 9 , in which the one of the first and second optical elements being an integral part is a lens.
11. The particle detection system of claim 9 , in which the one of the first and second optical elements being an integral part includes one of the interior surface portions configured to form opposed walls of a flow channel.
12. The particle detection system of claim 9 , in which the pair of spacers is formed of optically transparent material to function as ingress and egress windows of the view volume for the light beam.
13. The particle detection system of claim 12 , in which the light beam has a beam width and the light beam egress window has a window width, the beam width and the window width being substantially the same to illuminate the entire flow channel.
14. The particle detection system of claim 12 , in which the light beam has a beam width and the light beam egress window has a window width, the beam width being focused to a size that is smaller than the window width to enable higher intensity light detection of smaller particles entrained in the fluid stream.
15. The particle detection system of claim 9 , in which the first and second body sections and the pair of spacers arc fused into an integral structure, the pair of spacers defining surface interfaces between the spacers and the first and second body sections without bonding material present.
16. The particle detection system of claim 9 , in which the second body section is positioned between the view volume and the light collection lens system when the flow-through cell is inserted into the particle detection system.
17. The particle detection system of claim 9 , in which the first optical element is selected from a group consisting essentially of a transparent optical element, a lens, and a mirror.
18. The particle detection system of claim 9 , in which the second optical element is a lens.