z

CCD Microscope Artificial camera objective apposition compound eye PC

IOF

In an experimental setup for position detection using hyperacuity (top), a point source at infinity or on an edge at a finite distance is used as the object within the field of view of an artificial apposition compound eye (APCO; bottom). Rotating the ensemble of the APCO, the microscope objective, and the CCD camera simulates object movement.

To demonstrate the technique, the researchers fabricated an artificial compound eye as a microlens array on a planar glass substrate. To complete the imaging system, a sensor array with a pixel pitch different from that of the array was placed at the focal plane of the microlens array (reimaged via a relay lens) to record the image. To improve resolution, a pinhole array was placed at the actual (nonrelayed) focal plane of the microlens array (see figure).

In this multiaperture imaging device, the object space is sampled by the angu-lar-sensitivity functions of the different optical channels, which exhibit a finite angular width. The width is characterized by the acceptance angle, which also approximates the smallest resolvable angle between two image details. For example, 84 × 64 channels are sampling an overall FOV of 25° × 25° with an acceptance angle of 0.65°. The overlap between the FOVs of adjacent optical channels enables the extraction of subpixel information when the profile of the ASF is known.

 

Signal independent
of irradiance
An object—represented by a contrast
change—at some angular distance