Compact image scanner with large depth of field by compound eye system

Abstract

A compact image scanner is designed by using a compound eye system with plural optical units in which a ray path is folded by reflective optics. The optical units are aligned in two lines and take each image of a separated field of view (FOV), slightly overlapped. Since the optical units are telecentric in the object space and the magnification ratio is constant regardless of the object distance, the separated pieces of a total image are easily combined with each other even in the defocused position. Since the optical axes between adjacent optical units are crossed obliquely, object distance is derived from the parallax at each boundary position and an adequate deblurring process is achieved for the defocused image.

Compound eye image scanner optimally arranged for image combining and suppressing axial chromatic aberration by wavefront coding

“…We previously reported its reflective mirror version. 10,12 Since the diameter of the first lens is larger than the field of view due to telecentricity, the imaging units are aligned in a two-line staggered arrangement. As the object is scanned along the Y direction relative to the image scanner, the unit images shift one after the other with a gap in the two lines in the Y direction [Fig.…”

“…We previously developed two types of image scanners to achieve compactness: a lensless image scanner 9 and a compound eye image scanner implementing the above electrical combining processing. 10,11 Although the former type is very thin, its 300-dpi resolution is insufficient for a copier. The latter consists of plural reflective mirror imaging units, resulting in no chromatic aberration; however, high accuracy in the mirror shape and alignment, especially the tilt adjustment, is required.…”

Lensless image scanner using multilayered aperture array for noncontact imaging

“…We have developed an imaging scanner with 600-dpi resolution whose depth of field is larger than that of the traditional rod lens array scanner, by using reflective mirror arrays. 10,11 It is comparable in size to the traditional one. We apply the lensless direct contact method to make our scanner thinner.…”