Photography – Plural image recording – Stereoscopic
Reexamination Certificate
1999-02-25
2001-08-21
Gray, David M. (Department: 2851)
Photography
Plural image recording
Stereoscopic
C356S370000, C250S201800
Reexamination Certificate
active
06278847
ABSTRACT:
BACKGROUND
Different techniques are known for three dimensional imaging.
It is known to carry out three dimensional particle imaging with a single camera. This is also called quantative volume imaging. One technique, described by Willert and Gharib uses a special defocusing mask relative to the camera lens. This mask is used to generate multiple images from each scattering site on the item to be imaged. This site can include particles, bubbles or any other optically-identifiable image feature. The images are then focused onto an image sensor e.g. a charge coupled device, CCD. This system allows accurately, three dimensionally determining the position and size of the scattering centers.
Another technique is called aperture coded imaging. This technique uses off-axis apertures to measure the depth and location of a scattering site. The shifts in the images caused by these off-axis apertures are monitored, to determine the three-dimensional position of the site or sites.
There are often tradeoffs in aperture coding systems.
FIG. 1A
shows a large aperture or small f stop is used. This obtains more light from the scene, but leads to a small depth of field. The small depth of field can lead to blurring of the image. A smaller F stop increases the depth of field as shown in FIG.
1
B. Less image blurring would therefore be expected. However, less light is obtained.
FIG. 1C
shows shifting the apertures off the axis. This results in proportional shifts on the image plane for defocused objects.
The
FIG. 1C
system recovers, the three dimensional spatial data by measuring the separation between images related to off-axis apertures b, to recover the “z” component of the images. The location of the similar image set is used find the in-plane components x and y.
The current systems have certain drawbacks which are addressed by the present disclosure.
SUMMARY
The present system caries out aperture-induced three dimensional measuring by obtaining each image through each aperture. A complete image detector is used to obtain the entire image. The complete image detector can be a separate camera associated with each aperture, or a single camera that is used to acquire the different images from the different apertures one at a time.
The optical train is preferably arranged such that the aperture coded mask causes the volume to be imaged through the defocusing region of the camera lens. Hence, the plane of focus can be, and is intentionally outside of, the volume of interest. An aperture coded mask which has multiple openings of predefined shape, not all of which are necessarily the same geometry, and is off the lens axis, is used to generate multiple images. The variation and spacing of the multiple images provides depth information. Planar motion provides information in directions that are perpendicular to the depth. In addition, the capability to expose each of the multiple images onto a separate camera portion allows imaging of high density images but also allows proper processing of those images.
REFERENCES:
patent: 4645347 (1987-02-01), Rioux
patent: 5018854 (1991-05-01), Rioux
patent: 5075561 (1991-12-01), Rioux
patent: 5168327 (1992-12-01), Yamawaki
patent: 5270795 (1993-12-01), Blais
Dabiri Dana
Gharib Morteza
Modares Darius
California Institute of Technology
Fish & Richardson P.C.
Gray David M.
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