Drop characteristic measurement

1. A droplet measurement apparatus, comprising:

a light source having a collimating optical system;

an imaging device disposed to receive light from the collimating optical system;

a droplet illumination zone;

a steering optic that defines an optical path of light emitted by the light source and received by the imaging device; and

a droplet receptacle, wherein a portion of the optical path is directed through the droplet illumination zone across the droplet receptacle and the imaging device has an adjustable working range to vary a focal plane along the portion of the optical path.

2. The droplet measurement apparatus of claim 1 , further comprising a linear positioner coupled to the imaging device.

3. The droplet measurement apparatus of claim 1 , further comprising a lens with adjustable focal length optically coupled to the imaging device.

4. The droplet measurement apparatus of claim 3 , further comprising a linear positioner coupled to the imaging device.

5. The droplet measurement apparatus of claim 1 , wherein the optical path comprises a first portion between the collimating optical system and the droplet illumination zone and a second portion between the droplet illumination zone and the imaging device, and the first portion is not parallel to the second portion.

6. The droplet measurement apparatus of claim 1 , wherein the steering optic comprises at least two refractive or reflective members.

7. The droplet measurement apparatus of claim 1 , wherein the droplet receptacle is located below the portion of the optical path.

8. The droplet measurement apparatus of claim 1 , further comprising an alignment optic to align light from the light source with the steering optic.

9. A printing system, comprising:

a base;

a substrate support supported on the base; and

a print assembly supported on the base, the print assembly comprising:

a dispenser support extending across the substrate support; and

a dispenser assembly movably coupled to the dispenser support; and

a droplet measurement apparatus supported on the base, the droplet measurement apparatus comprising:

a housing;

a light source disposed in the housing, the light source comprising a collimating optical system;

an imaging device disposed to receive light from the collimating optical system;

a droplet illumination zone;

a steering optic that defines an optical path of light emitted by the light source and received by the imaging device; and

a droplet receptacle, wherein a portion of the optical path is directed through the droplet illumination zone across the droplet receptacle and the imaging device has an adjustable working range to vary a focal plane along the portion of the optical path.

10. The printing system of claim 9 , further comprising a linear positioner disposed in the housing and coupled to the imaging device.

11. The printing system of claim 9 , further comprising a lens with adjustable focal length disposed in the optical path between the droplet illumination zone and the imaging device.

12. The printing system of claim 11 , wherein the steering optic comprises at least two refractive or reflective members.

13. The printing system of claim 11 , further comprising a linear positioner disposed in the housing and coupled to the imaging device.

14. The printing system of claim 11 , wherein the imaging device is movable with respect to the housing.

15. The printing system of claim 11 , wherein the steering optic comprises two prisms, the dispenser assembly comprises one or more dispensers, and a distance between the prisms is greater than a dimension of a dispenser of the one or more dispensers.

16. The printing system of claim 15 , wherein the dispenser assembly further comprises a nozzle plate, and the nozzle plate has notches with spacing that matches the spacing of the prisms.

17. The printing system of claim 9 , wherein the dispenser assembly is movable to position the dispenser within the illumination zone.

18. A printing system, comprising:

a base;

a substrate support supported on the base; and

a print assembly supported on the base, the print assembly comprising:

a dispenser support extending across the substrate support; and

a dispenser assembly movably coupled to the dispenser support; and

a droplet measurement apparatus supported on the base, the droplet measurement apparatus comprising:

a housing;

a light source disposed in the housing, the light source comprising a collimating optical system;

an imaging device disposed to receive light from the collimating optical system;

a droplet illumination zone;

a steering optic that defines an optical path of light emitted by the light source and received by the imaging device; and

a droplet receptacle, wherein a portion of the optical path is directed through the droplet illumination zone across the droplet receptacle and the imaging device has a lens with adjustable focal length, a linear positioner, or both to vary a focal plane along the portion of the optical path.

19. The printing system of claim 18 , wherein the steering optic comprises two prisms, the dispenser assembly comprises one or more dispensers, and a distance between the prisms is greater than a dimension of a dispenser of the one or more dispensers.

20. The printing system of claim 19 , wherein the droplet measurement apparatus further comprises an alignment optic to align light from the light source with the steering optic.