Constant magnification lens for vision system camera
First Claim
1. A vision system for acquiring images of objects over a range of focal distances within a field of view comprising:
- an image sensor operatively connected to a vision processor;
a constant magnification lens assembly oriented along an optical axis that receives light from a scene and transmits the light to the image sensor, the constant magnification lens assembly including a front lens assembly and a rear lens assembly such that an aperture stop of the constant magnification lens assembly is between a back surface of the front lens assembly and a focal point of the front lens assembly; and
wherein the front lens assembly has a first dimension that is smaller than a second dimension associated with the field of view.
1 Assignment
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Accused Products
Abstract
This invention provides a lens assembly for a vision system, allowing for a constant magnification at various focal distances. The lens assembly resides movably/adjustably along the optical axis relative to the sensor. In an embodiment, the lens assembly includes a fixed rear lens and a front lens that is moved mechanically to focus the object image on the image sensor. The lens assembly can alternatively include a liquid lens that is controlled to adjust magnification with respect to a fixed front lens so as to maintain a constant system magnification. The liquid lens resides between the (fixed) front lens assembly and the image sensor and can be controlled to focus the image onto the image sensor.
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Citations
15 Claims
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1. A vision system for acquiring images of objects over a range of focal distances within a field of view comprising:
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an image sensor operatively connected to a vision processor; a constant magnification lens assembly oriented along an optical axis that receives light from a scene and transmits the light to the image sensor, the constant magnification lens assembly including a front lens assembly and a rear lens assembly such that an aperture stop of the constant magnification lens assembly is between a back surface of the front lens assembly and a focal point of the front lens assembly; and wherein the front lens assembly has a first dimension that is smaller than a second dimension associated with the field of view. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A vision system for acquiring images of an object over a range of focal distances within a field of view comprising:
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an image sensor operatively connected to a vision processor; a constant magnification lens assembly oriented along an optical axis that receives light from a scene and transmits the light to the image sensor, the constant magnification lens assembly including a liquid lens assembly oriented between the image sensor and a front lens assembly, the front lens assembly comprising one or more fixed lenses, and the liquid lens assembly including an electrical interface that varies a magnification m2 of the liquid lens assembly, wherein the front lens assembly and liquid lens assembly are arranged in a fixed spatial relationship therebetween; and a controller that selectively adjusts the magnification m2 of the liquid lens assembly to maintain focus on the object at a constant system magnification M at each focal distance of the range of focal distances, wherein M is defined as a distance between the liquid lens assembly and the image sensor (d2) divided by a distance between the liquid lens assembly and the front lens (d1) such that M=d2/d1. - View Dependent Claims (8, 9, 10, 11, 12, 13)
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14. A method for acquiring images of an object over a range of focal distances within a field of view comprising the steps of:
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providing an image sensor operatively connected to a vision processor and a constant magnification lens assembly oriented along an optical axis that receives light from a scene and transmits the light to the image sensor, the constant magnification lens assembly including a front lens assembly and a rear lens assembly such that an aperture stop of the constant magnification lens assembly is between a back surface of the front lens assembly and a focal point of the front lens assembly; and iteratively adjusting the constant magnification lens assembly until the object achieves a desired focus at the image sensor. - View Dependent Claims (15)
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Specification