A computer rendered drawing of the four stages that comprise the testbed motion system. Two translation stages move along the X and Z directions. The elevation rotation stage is mounted to the azimuth rotation stage by a counterweighted right-angle mounting platform. A mirror is mounted in a cell on the elevation stage. The combination of the two rotation stages can point the mirror in any direction. Drawings courtesy of Newport Corporation (Irvine, CA).
AWARE-2 camera on the testbed setup. The testbed consists of two 600 mm translation stages and two rotation stages (elevation and azimuth). The object space is focused at infinity by using a telescope, which projects an arbitrary image from the mini projector or resolution target. The projector area corresponds to an image size on the micro-camera sensor of 248 × 166 pixels. The source path from either the projector or resolution target follows through the telescope, reflects on the elevation stage mirror, and propagates through the Gigagon objective and into the micro-camera optics. The projector is located on the opposite arm of the resolution target, enabling both targets to be used.
A ray trace of the telescope, the objective, and a micro-camera. The mirror is in the beam path between the telescope and the camera to direct the field into the camera entrance pupil.
A rendering of the chief ray beam path using a Python-based testbed simulator. This program tests the range of motion of the stages to ensure that these are within the limits of the testbed, and also is used to control the testbed.
A diagram of a ray incident from the telescope, reflected from the mirror, and into the camera entrance pupil. The vectors including the unit vector incident onto the mirror, reflecting from the mirror, and into the camera are marked. A Rodriguez rotation defined by the axis and rotation angle ω C transforms the testbed coordinates to camera coordinates.
Distance errors between two placements of the camera relative to the testbed after coordinate transform correction. The entire camera was rotated, moved, and then re-calibrated. The errors are still significant due to pointing errors of the micro-optics introducing errors in the coordinate transform. Reproduced with permission from D. S. Kittle, D. L. Marks, and D. J. Brady, Proc. SPIE 8660, 866006 (2013). Copyright 2013 Society of Photo-Optical Instrumentation Engineers.
Errors between two different placements of the camera on the testbed before coordinate transform. The errors in Fig. 6 are decreased by 85% after the coordinate transform. Reproduced with permission from D. S. Kittle, D. L. Marks, and D. J. Brady, Proc. SPIE 8660, 866006 (2013). Copyright 2013 Society of Photo-Optical Instrumentation Engineers.
Thermal drift in time for micro-camera one at the center of the field. The temperature differential was 25°C at time zero and 32°C at 3000s. The camera was then cooled back to ambient temperature with steady-state operation near 7000 s.
Zone plate measurements for micro-camera number one. The distortion, image space mapping, and illumination profile are evident from this data set, consisting of 81 independent object-space vectors projected into the AWARE-2 objective.
Comparison between MTF calculation methods. Imatest slanted edge method using an edge from a chrome 1951 USAF resolution target and flat field correction with 30 averaged frames, Imatest without flat field correction, Zemax Model * pixel transfer function, proposed sinusoidal method using a monochrome sensor, sinusoidal method using a color Bayer sensor, and Imatest slanted edge at 48 m without testbed system and telescope.
MTF values at the center for 87 micro-cameras at 45 cycles/mm. Micro-cameras with poor MTF performance indicate optics that are not aligned correctly, incorrect focus calibration, and focal plane mis-alignment. Using this data, micro-cameras can be quickly assessed and repaired before taking the camera out in the field. Reproduced with permission from D. S. Kittle, D. L. Marks, and D. J. Brady, Proc. SPIE 8660, 866006 (2013). Copyright 2013 Society of Photo-Optical Instrumentation Engineers.
MTF surface for the replacement micro-optic and Gigagon at 133 cycles/mm. The MTF surface was calculated for 81 Chebyshev node points on the detector.
Flat field measurement for a glass micro-optic, averaged over thirty frames to better estimate the sensor values over time.
Telescope prescription for use with projector. Glasses are Schott (Elmsford, NY) type. Lenses are from Thorlabs (Newton, NJ) and Edmund Optics (Barrington, NJ).
List of variables used in analysis.
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