Optical: systems and elements – Single channel simultaneously to or from plural channels – By surface composed of lenticular elements
Reexamination Certificate
1997-11-04
2001-06-26
Mack, Ricky (Department: 2873)
Optical: systems and elements
Single channel simultaneously to or from plural channels
By surface composed of lenticular elements
C359S626000, C250S234000
Reexamination Certificate
active
06252717
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a device for three-dimensional investigation of an object.
A device of this kind is known from DE 40 35 799. In that patent, an illuminating grid with a pixel size is imaged on a receiver array, which matches the pixel size of the photosensitive areas of the receiver array or is a whole-number multiple of said array. The diaphragm action of the receiver array is utilized. A system of this kind has the disadvantage that during the evaluation of images taken from various object planes to determine the depth values, the absolute brightness values are always evaluated and their maximum must be determined.
A device that makes it possible to determine the distance of a measured location with zero signal detection and with anamorphic imaging of a point is also known. The light from a laser diode is imaged on the object to be illuminated and the light reflected from the object is imaged by an anamorphic lens in such fashion that an approximately circular image of the point results in an intermediate plane between the two focal planes defined by the anamorphic lens. Outside this intermediate plane, with sufficient evaluation of the image by radiation receivers designed for the purpose, a system of this kind supplies a directional signal that indicates in which direction the position of the measured object differs from the set position. Systems of this kind are used in compact disk players. However, only a single point on the object is picked up in the course of this process. Therefore, measurements using a system of this kind require a great deal of time in metrology, with many measurement points having to be detected in a short time. This is especially true when large areas of the object are to be measured.
BRIEF SUMMARY OF THE INVENTION
The present invention has the goal of providing a device that makes it possible to determine the set interval using zero signal detection and in this way to detect many measurement points at the same time.
The system according to the invention has the advantage that the spacing of the individual measurement points is determined for example by zero signal detection and that very many measurement points are detected simultaneously. This is performed economically because receiver arrays, preferably CCD arrays and arrays made of anamorphic lenses, are used as the radiation receivers, which can be manufactured economically by compression molding for example.
Signal detection is implemented by the arrangement of the receiver array relative to the array of anamorphic lenses in such fashion that, at the set spacing, the image of the light reflected from the illuminated point on the sample and imaged by an anamorphic lens falls in the shape of a circle on four radiation receivers (pixels) of the receiver array in such fashion that each radiation receiver receives the same amount of light or an amount of light that is determined relative to the amounts of light that fall on the radiation receiver or receivers associated with this point.
The system according to the invention differs from the system described in Patent DE 40 35 799 in that the diaphragm function of the radiation receivers arranged in an array is utilized in the latter, with the photosensitive areas of said receivers being separated from one another by gaps. Spacing detection is performed by evaluating the intensity maximum detected on each pixel of the radiation receiver array. For this purpose, a measurement series is performed that stores the values for several different z-positions of the object in the computer. For each pixel, this determines the z-position at which its intensity has its maximum. The spacing value to be determined is obtained from the latter. In the present invention, on the other hand, the difference or a set ratio of the signals of adjacent pixels of the receiver array is evaluated. The place where the zero value or the set ratio is reached is the set position that supplies the depth value to be determined. Receiver arrays are used for this purpose that have no zone that is insensitive to light, or only a very small zone of this kind, between adjacent pixels. For detecting the spacing signal in the present invention, it is necessary to use receiver arrays with photosensitive areas that are directly adjacent to one another. For this reason, the system according to the present invention differs basically from that described in the abovementioned DE.
The system according to the invention is especially suitable for three-dimensional measurement of mechanical parts in incident light and for recording 3-D images of fluorescent objects. For mechanical parts, a semi-transparent mirror is placed in known fashion in the beam path to separate the illuminating light from the light reflected from the object. For fluorescence applications, a dichroic mirror is used in a manner known of itself, and possibly light filters as well, to separate the illuminating light and the light emitted by fluorescence from the object.
REFERENCES:
patent: 5239178 (1993-08-01), Derndinger et al.
patent: 5260826 (1993-11-01), Wu
patent: 5369659 (1994-11-01), Furumoto et al.
patent: 5493391 (1996-02-01), Neal et al.
patent: 26 34 655 C2 (1984-05-01), None
patent: 4017485A1 (1991-12-01), None
patent: 69313024T2 (1993-12-01), None
patent: 64-55513 (1989-03-01), None
Fish & Richardson P.C.
Mack Ricky
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