System for using optical sensor focus to identify feature heights on objects being produced in a three-dimensional object printer
A three-dimensional object printer generates image data of an object being formed in the printer with an optical sensor and identifies the heights of object features above a substrate on which the object is being formed. A controller operates one or more actuators to move the optical sensor at a plurality of distances above the object to generate image data of the object at a plurality of heights above the object. The controller identifies the distances of the features of the object with reference to the image data generated by the optical sensor and the focal length of the optical sensor.
1. A printer comprising:
a substrate positioned opposite a material applicator to enable an object to be formed on the substrate with material received from the material applicator;
an optical sensor having at least one light source and a plurality of photo detectors arranged in a linear array, the optical sensor being configured to generate data corresponding to an upper surface of the object on the substrate;
at least one actuator operatively connected to the optical sensor or the substrate; and
a controller operatively connected to the optical sensor and the at least one actuator, the controller being configured to operate the at least one actuator to move the optical sensor or the object to a plurality of distances between the object and the optical sensor to enable the optical sensor to generate image data of features of the object as the optical sensor moves relative to the object across a width or length of the object, and to identify features of the object with reference to the data received from the optical sensor and a focal length of the optical sensor.
2. The printer of claim 1 , the controller being further configured to:
identify distances of the features of the object above the substrate with reference to the image data generated by the optical sensor; and
compare the identified distances of the features to data corresponding to expected distances of the features of the object above the substrate.
3. The printer of claim 2 , the controller being further configured to:
adjust operation of the printer in response to a difference between the identified distances of the features of the object above the substrate and the expected distances of the features being greater than a predetermined threshold.
4. The printer of claim 1 , the controller being further configured to move the optical sensor or the object bi-directionally.
5. The printer of claim 1 , the controller being further configured to:
operate the at least one actuator to position the optical sensor at the plurality of distances from the object with reference to the focal length of the optical sensor.
6. The printer of claim 1 , the at least one light source of the optical sensor further comprising:
a source of white light oriented to illuminate a field of view of the photo detectors of the optical sensor.
7. The printer of claim 1 , the at least one light source further comprising:
a pair of light sources positioned on opposite sides of the linear array of photo detectors.
8. The printer of claim 7 , the pair of light sources further comprising:
a first light source that emits light of a first color;
a second light source that emits light a second color, the first color and the second color being different; and
the controller is configured to detect the first color and the second color from the image data generated by the plurality of photo detectors in the optical sensor.
9. The printer of claim 1 , the controller being further configured to identify the height of object features from image data generated by the plurality of photo detectors in the optical sensor receiving light specularly reflected by the surface of the object.
10. The printer of claim 9 further comprising:
another actuator being operatively connected to the sensor; and
the controller being operatively connected to the other actuator, the controller being further configured to operate the other actuator to rotate the optical sensor and change the specularly reflection of the light by the surface of the object.
11. The printer of claim 1 , the controller being further configured to identify the height of object features from image data generated by the plurality of photo detectors in the optical sensor receiving light scattered by the surface of the object.