BACKGROUND

Technical Field

The present invention relates to automatic robotic alignment of optical components during manufacture or testing and, more particularly, to apparatus and methods for manufacturing and/or testing optical components, such as cameras or other workpieces, having wide fields of view, wide ranges of fields of view or ranges of workpieces, each having a different size field of view.

Related Art

Robots are used in many precision manufacturing and/or testing processes. For example, robots are used to precisely align lenses before digital camera sensors, such as in the manufacture or testing of cellular telephones and cameras for automobiles. In other examples, robots align ends of optical fibers before lasers or light sensors in the manufacture of telecommunication and computer network equipment. Many of the lenses are quite small, on the order of several millimeters in diameter, and must, therefore, be positioned with high precision, often on the order of about ±5 μm or less, relative to the sensors or lasers.

To keep costs down, less-than-precise methods are often used to manufacture optical elements for the lenses and to mount the optical elements in lens housings. Consequently, the optical elements and lenses are often not uniform, from piece to piece. That is, dimensions and symmetries of the components often vary from lens to lens or other optical components, resulting in variations in focal length and orientation of the optical axes of the components.

To compensate for such variations, several known methods are used to custom align each lens to its corresponding sensor. One method, developed by Automation Engineering, Inc. (“AEi”), Wilmington, Mass., involves using a robot to attach a lens barrel to an image sensor or its substrate, or to a camera housing that includes the image sensor, by an adhesive. The position of the lens barrel, relative to the image sensor, is adjusted in free space by the robot, while image data generated by the image sensor is analyzed by a processor. The processor commands the robot to position the lens barrel for best optical performance of the lens. This method is referred to as “active alignment.” The robot then holds the lens barrel in position until the adhesive cures sufficiently to prevent objectionable creep once the robot releases the lens barrel.

Using this method, the position of the lens may be adjusted along all three linear axes (x, y and z), and pitch (rotation about the x axis) and roll (rotation about the y axis) of the lens may be adjusted, to achieve a lens position and orientation, relative to the sensor, that compensates for some, most or all imperfections in the optical elements and in the way the optical elements are mounted within the barrel with respect to the position of the image sensor. This method is referred to as aligning about five degrees of freedom.

A refinement of this method, also develop by Automation Engineering, Inc., involves the robot also rotating the lens about the optical axis of the lens or about the z axis to optimize image quality, to compensate for angular lens asymmetries in this axis. Adding this refinement to the 5-degree of freedom alignment method provides a 6-degree of freedom alignment. In other cases, this 6-degree of freedom alignment is performed for sensor alignment, i.e., the lens position is fixed, while the robot holds and positions the sensor to perform the alignment.

Thus, active alignment involves measuring one or more key optical performance attributes of a combination of components during manufacture or testing and using the measured attributes in a feedback loop to control the manufacture or provide test results. For example, a visual target, such as a test pattern, may be disposed within a viewing angle (field of view) of a lens-and-image-sensor combination while a robot steps or continuously moves (collectively “scans”) the lens through a series of positions (ex., along the x, y and z axes) and orientations (ex., tips, tilts and rotations about the z axis). A processor analyzes image data from the sensor at each position and/or orientation and, based on this analysis, the processor controls the robot to position and orient the lens for optimum image quality. The lens is then fixed in position, relative to the sensor, or vice versa, such as by an adhesive. Active alignment is, therefore, able to compensate for piece to piece variations in components.

Similarly, active testing involves a robot scanning a lens, camera or other unit under test (workpiece) through a series of positions and orientations, while a processor analyzes image data from the sensor at each position and/or orientation and, based on this analysis, the processor quantifies the image quality of the unit under test. Such tests may be used for quality control, such as to accept or reject previously manufactured units.

As noted, active alignment or active testing involves a suitable target. The target should fill the field of view of the unit under test. Otherwise, portions of the field of view of the unit under test would not be tested. Similarly, target features should be appropriately sized and positioned to provide meaningful test results.

However, some workpieces, such as front-view automotive cameras, are used for several tasks, such as collision avoidance, sign reading, lane keeping and pedestrian tracking. When building or testing such a camera, the test should include several different fields of view, for example: (a) an on-axis (0 degrees) at 100 m (meters) field of view for down-road collision avoidance, (b) a 10 degrees field of view for sign reading, (c) a 20 degrees field of view for lane keeping and (d) a 40 degrees field of view for pedestrian tracking. It would be desirable to build or test a workpiece at several different fields of view and/or at several different focal distances on the same equipment, without requiring changes in equipment hardware.

In some cases, equipment is used to manufacture or test multiple types of workpieces, each type of workpiece having a different field of view. For example, a narrow, such as a 10 degree, field of view camera may be manufactured or tested during a morning shift, and a surround-view, such as a 180 degree, camera may be manufactured or tested in an afternoon shift on the same equipment. It would be desirable to be able to build or test both cameras on the same equipment, without requiring changes in equipment hardware. However, no single target may be appropriate for all the camera types. Similarly, each camera type may require the target to be located a different optical distance from the unit under test.

Current robotic manufacturing or testing equipment requires labor-intensive reconfiguration to handle workpieces having a wide range of fields of view and/or a wide range of optical distances.

SUMMARY OF EMBODIMENTS

An embodiment of the present invention provides a system for automatically aligning, and/or testing alignment of, a workpiece. The workpiece has a workpiece optical axis. During a first time period, the workpiece includes a first lens and a first image sensor collectively having a first field of view. During a second time period, the workpiece includes a second lens and a second image sensor collectively having a second field of view. The second field of view is wider than the first field of view.

The system includes a processor, a target and an intermediate lens. The target is configured to translate substantially along the respective workpiece optical axis, in response to a first command from the processor, to a position specified by the processor. The processor is configured to thereby selectively adjust optical spacing between the target and the workpiece.

The intermediate lens is disposed optically between the target and the workpiece. The intermediate lens is configured to form, during the first time period, a first image of the target on the first image sensor, via a sequence of the intermediate lens and the first lens. The first image fills a first fraction of the first image sensor.

The intermediate lens is configured to form, during the second time period, a second image of the target on a central portion of the second image sensor, via a sequence of the intermediate lens and the second lens. The second image fills a second fraction of the second image sensor smaller than the first fraction.

The system also includes a plurality of collimators. The plurality of collimators is disposed peripheral to the intermediate lens. Each collimator has a respective reticle. Each collimator is configured to project, during the second time period, a respective image of the reticle, through the second lens, on the second image sensor, without the image of the reticle passing through the intermediate lens. The image of the reticle extends outside an outer boundary of the second image of the target on the second image sensor.

The system also includes a robot. The robot is configured to grasp and, in response to a second command from the processor, scan at least a portion of the workpiece along a trajectory.

The processor is configured to analyze signals acquired from the workpiece while the workpiece is scanned along the trajectory and thereby quantitatively assess a degree of optical alignment of the workpiece.

Optionally, in any embodiment, focal length of each collimator of the plurality of collimators may be adjustable. Each collimator may be configured to adjust its focal length in response to a third command from the processor.

Optionally, in any embodiment, the plurality of collimators may include at least four collimators.

Optionally, in any embodiment, the plurality of collimators may be immobile, relative to the intermediate lens, along the workpiece optical axis.

Optionally, in any embodiment, the first field of view may be less than about 60°.

Optionally, in any embodiment, the second field of view may be greater than about 60°.

Optionally, in any embodiment, each collimator of the plurality of collimators may be oriented toward an entrance pupil center of the workpiece. Location of the entrance pupil center may be based at least in part on a field of view of interest.

Optionally, any embodiment may also include, for each collimator, a respective folding optical element. The folding optical element may be configured to redirect the respective image of the reticle toward an entrance pupil center of the workpiece. Location of the entrance pupil center may be based at least in part on a field of view of interest.

Optionally, in any embodiment, an angle of each respective folding optical element may be adjustable.

Optionally, in any embodiment, an optical axis of each collimator of the plurality of collimators may be oriented parallel to the workpiece optical axis.

Optionally, in any embodiment, an optical axis of each collimator of the plurality of collimators may be adjustable, relative to the workpiece optical axis.

Optionally, in any embodiment, the plurality of collimators may be attached via a kinematic mount.

Optionally, any embodiment may also include an optical stage configured to releasably receive the plurality of collimators. Number and/or disposition of collimators in the plurality of collimators may be adjustable.

Optionally, in any embodiment, each collimator of the plurality of collimators may be individually removable.

Optionally, in any embodiment, at least some of the respective reticles of the plurality of collimators may be different from other of the respective reticles of the plurality of reticles.

Optionally, in any embodiment, at least some collimators of the plurality of collimators may be configured to project respective images of the respective reticles with different wavelengths of light from other of the collimators of the plurality of collimators.

Optionally, in any embodiment, wavelength of light from the plurality of collimators may be adjustable.

Optionally, in any embodiment, color and/or intensity of the images of the respective reticles may be adjustable.

Optionally, in any embodiment, at least some collimators of the plurality of collimators may be configured to project respective images of the respective reticles at different angles, relative to the workpiece optical axis, from other of the collimators of the plurality of collimators.

Optionally, in any embodiment, the plurality of collimators may be configured to translate along the respective workpiece optical axis, in response to a fourth command from the processor, to a position specified by the processor. The processor may be configured to thereby selectively adjust optical spacing between the plurality of collimators and the workpiece in coordination with the optical spacing between the target and the workpiece.

Optionally, in any embodiment, the plurality of collimators may be immobile, relative to the intermediate lens, along the workpiece optical axis.

Optionally, in any embodiment, the plurality of collimators may be mobile, relative to the intermediate lens, along the workpiece optical axis.

Optionally, in any embodiment, the processor may be configured to automatically control projection by the plurality of collimators of the respective images of the respective reticles, based at least in part on magnitude of the field of view of a current workpiece.

Another embodiment of the present invention provides a non-transitory computer-readable medium. The Medium is encoded with instructions. When executed by a processor, the instructions establish processes for performing a computer-implemented method of automatically aligning, and/or testing alignment of, a workpiece. The workpiece has a workpiece optical axis. During a first time period, the workpiece includes a first lens and a first image sensor collectively having a first field of view. During a second time period, the workpiece comprises a second lens and a second image sensor collectively having a second field of view wider than the first field of view.

The processes include a process configured to translate a target substantially along the respective workpiece optical axis, in response to a first command from the processor, to a position specified by the processor. The processor is configured to thereby selectively adjust optical spacing between the target and the workpiece. The processor is configured, during the first time period, to cause formation of a first image of the target on the first image sensor, via a sequence of an intermediate lens, disposed optically between the target and the workpiece, and the first lens. The first image fills a first fraction of the first image sensor. The processor is configured, during the second time period, to cause formation of a second image of the target on a central portion of the second image sensor, via a sequence of the intermediate lens and the second lens. The second image fills a fraction of the second image sensor smaller than the first fraction.

The processes also include a process configured to control a plurality of collimators. The plurality of collimators is disposed peripheral to the intermediate lens. Each collimator has a respective reticle. Each collimator is configured to project, during the second time period, a respective image of the reticle, through the second lens, on the second image sensor, without the image of the reticle passing through the intermediate lens. The image of the reticle extends outside an outer boundary of the second image of the target on the second image sensor.

The processes also include a process configured to control a robot. The robot is configured to grasp and, in response to a second command from the processor, scan at least a portion of the workpiece along a trajectory.

The processes also include a process configured to analyze signals acquired from the workpiece while the workpiece is scanned along the trajectory and thereby quantitatively assess a degree of optical alignment of the workpiece.

Optionally, the plurality of collimators may be immobile, relative to the intermediate lens, along the workpiece optical axis.

