1. An automated system for tool mark analysis comprising
an acquisition mechanism for acquiring 3D data of tool marks left on the surfaces of specimens by tools operating on the specimens, said acquisition mechanism being capable of acquiring 3D from impressed tool marks and from striated tool marks;
a signature generation module for generating tool mark signatures from the acquired data corresponding to the respective tool marks;
an analysis unit for statistically evaluating pairs of the tool mark signatures for impressed tool marks in relation to one another and for statistically evaluating pairs of the tool mark signatures for striated tool marks in relation to one another, said analysis unit being capable of computing a numerical similarity value for each pair of tool mark signatures reflecting the degree of similarity between the tool mark signatures of each pair, said analysis unit employing a frequency domain-based similarity metric to compute a similarity value for each pair of tool mark signatures for impressed tool marks and employing a relative distance similarity metric to compute a similarity value for each pair of tool mark signatures for striated tool marks; and
a database in which said similarity values are stored.
2. The automated system for tool mark analysis recited in claim 1 wherein said database comprises questioned similarity values associated with questioned tool mark signatures of unknown origin and reference similarity values associated with control tool mark signatures of known origin corresponding to control specimens.
3. The automated system for tool mark analysis recited in claim 2 wherein said analysis unit is capable of performing a statistically based classification for the questioned similarity values against the reference similarity values.
4. An automated system for tool mark analysis comprising
an acquisition mechanism for acquiring 3D data of tool marks left on the surfaces of specimens by tools operating on the specimens, said acquisition mechanism including a 2D imaging mechanism for identifying regions of interest on the surfaces of the specimens for 3D data acquisition;
a signature generation module for generating tool mark signatures from the acquired data corresponding to the respective tool marks;
an analysis unit for statistically evaluating pairs of the tool mark signatures in relation to one another, said analysis unit being capable of computing a numerical similarity value for each pair of tool mark signatures reflecting the decree of similarity between the tool mark signatures of each pair; and
a database in which said similarity values are stored.
5. An automated system for tool mark analysis comprising
an acquisition mechanism for acquiring 3D data of tool marks left on the surfaces of specimens by tools operating on the specimens;
a signature generation module for generating tool mark signatures from the acquired data corresponding to the respective tool marks;
a data pre-processing module for operating on the acquired 3D data prior to signature generation, said data pre-processing module being capable of decimating the acquired 3D data, identifying unreliable data points in the acquired 3D data, replacing the unreliable data points with interpolated values, and identifying sections of the data of greatest reliability to obtain pre-processed data for each tool mark;
an analysis unit for statistically evaluating pairs of the tool mark signatures in relation to one another, said analysis unit being capable of computing a numerical similarity value for each pair of tool mark signatures reflecting the degree of similarity between the tool mark signatures of each pair; and
a database in which said similarity values are stored.
6. The automated system for tool mark analysis recited in claim 5 and further comprising a normalization module for operating on the pre-processed data prior to signature generation, said normalization module being capable of transforming the pre-processed data for each tool mark into a Cartesian coordinate representation and normalizing the Cartesian coordinate representation with respect to a reference surface.
7. The automated system for tool mark analysis recited in claim 6 wherein said normalization module is capable of applying a second-order leveling algorithm to the pre-processed data to obtain second-order leveled data for each tool mark, and applying a first-order leveling algorithm to the second-order leveled data to obtain first-order leveled data for each tool mark.
8. The automated system for tool mark analysis recited in claim 7 wherein the tool marks are striated tool marks and said signature generation module is capable of histogram equalizing the normalized data to obtain histogram equalized data, estimating local gradients for the histogram equalized data for each tool mark, identifying the dominant gradient direction for each tool mark from the corresponding local gradients, identifying the direction of the striations for each tool mark, projecting each tool mark onto a plane perpendicular to the direction of its striations to obtain a cross-sectional profile for each tool mark, and filtering the profiles to obtain the tool mark signatures for the tool marks.
9. The automated system for tool mark analysis recited in claim 8 wherein the similarity values computed by said analysis unit are based on relative distance similarity metrics.
10. The automated system for tool mark analysis recited in claim 7 wherein the tool marks are impressed tool marks and said signature generation module is capable of creating a data set from the normalized data for each tool mark contained in a two-dimensional data set to obtain the tool mark signature for each tool mark.
11. The automated system for tool mark analysis recited in claim 10 wherein the similarity values computed by said analysis unit are based on improved fast normal cross correlations.
12. The automated system for tool mark analysis recited in claim 6 and further including a calibration module for calculating calibration parameters associated with misalignments of the acquisition mechanism for use by said normalization module to refine the acquired data to compensate for the misalignments.
13. An automated method for tool mark analysis comprising the steps of
acquiring 3D data of tool marks left on the surfaces of specimens by tools operating on the specimens;
generating tool mark signatures for the respective tool marks from the acquired 3D data via a computer;
statistically evaluating pairs of the tool mark signatures in relation to one another via the computer, wherein said step of statistically evaluating includes implementing a frequency domain-based similarity metric where the pairs of tool mark signatures are for impressed tool marks and said step of statistically evaluating includes implementing a relative distance similarity metric where the pairs of tool mark signatures are for striated tool marks; and
providing a numerical similarity value via the computer for each pair of tool mark signatures reflecting the degree of similarity between the tool mark signatures of each pair.
14. An automated method for tool mark analysis comprising the steps of
acquiring 3D data of tool marks left on the surfaces of specimens by tools operating on the specimens;
preprocessing the acquired data to eliminate unreliable data points;
normalizing the preprocessed data to eliminate extraneous artifacts;
generating tool mark signatures for the respective tool marks from the acquired 3D data via a computer subsequent to said steps of preprocessing and normalizing;
statistically evaluating pairs of the tool mark signatures in relation to one another via the computer; and
providing a numerical similarity value via the computer for each pair of tool mark signatures reflecting the decree of similarity between the tool mark signatures of each pair.
15. The automated method for tool mark analysis recited in claim 14 wherein said step of preprocessing includes decimating the data, identifying unreliable data points, replacing unreliable data points with interpolated values, and identifying the most reliable section of the data.
16. The automated method for tool mark analysis recited in claim 14 wherein said step of normalizing includes transforming the preprocessed data into a Cartesian coordinate representation and normalizing the Cartesian coordinate representation with respect to a reference surface.
17. The automated method for tool mark analysis recited in claim 16 wherein said step of normalizing includes second order leveling of the data and first order leveling of the data.
18. The automated method for tool mark analysis recited in claim 17 wherein the tool marks are impressed tool marks and said step of generating includes filtering the normalized data.
19. The automated method for tool mark analysis recited in claim 16 wherein the tool marks are striated tool marks and said step of generating includes histogram equalizing the normalized data, estimating local gradients for every point of the histogram equalized data, identifying the dominant gradient direction, identifying the direction of the striations of the tool mark, obtaining a cross-sectional profile of the tool mark, and filtering the profile.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
What is claimed is:
1. An optical tap for selectively removing a portion of an optical signal communicated through a waveguide comprising:
a substrate having at least two waveguides disposed thereon;
a respective junction formed by each intersection of the waveguides;
each waveguide formed from materials selected to allow optical signals to communicate therethrough; and
a respective electrode heater disposed adjacent to each junction of the waveguides for use in heating the associated junction to direct, by internal reflection, the portion of the optical signal from one of the waveguides to the other waveguide.
2. The optical tap of claim 1 further comprising:
a first array of waveguides and a second array of waveguides; and
the waveguides of the first array intersecting the waveguides of the second array at a selected angle ().
3. The optical tap of claim 2 further comprising the selected angle () having a value between approximately two degrees and eight degrees depending on microstructure of the junction and associated index of refraction of the waveguides.
4. The optical tap of claim 2 further comprising the selected angle () having a value of approximately three degrees.
5. The optical tap of claim 2 further comprising the selected angle () having a value of approximately six degrees.
6. A variable optical tap for selectively removing a portion of an optical signal communicated through a waveguide comprising:
a first array of waveguides and a second array of waveguides disposed on a substrate;
the waveguides of the first array extending substantially parallel with each other and the waveguides of the second array extending substantially parallel with each other;
the waveguides of the second array intersecting the waveguides of the first array at a selected angle ();
the intersection of the waveguides of the first array and the second array forming a plurality of respective junctions;
a layer of cladding disposed over the waveguides including the respective junctions;
the layer of cladding disposed between adjacent waveguides;
a plurality of electrode heaters respectively disposed on the layer of cladding adjacent to the junctions;
a source of electrical current coupled with the electrode heaters; and
each electrode heater operable to selectively heat the respective junction to provide internal reflection which directs the portion of the optical signal from one waveguide of the first array to an associated waveguide of the second array.
7. The optical tap of claim 6 further comprising the selected angle () having a value greater than two degrees.
8. The optical tap of claim 6 further comprising the selected angle () having a value less than eight degrees.
9. The optical tap of claim 6 further comprising the selected angle () having a value of approximately six degrees.
10. A method for selectively tapping a portion of an optical signal communicated through a waveguide comprising:
communicating the optical signal through a first waveguide formed on a substrate;
supplying electrical current to a electrode heater disposed adjacent to a junction formed by an intersection between the first waveguide and a second waveguide formed on the substrate;
heating the junction with the associated electrode heater to provide internal reflection at the intersection of the waveguides; and
varying the amount of electrical current supplied to the electrode heater to vary the portion of the optical signal directed from the first waveguide to the second waveguide by the internal reflection.
11. The method of claim 10 further comprising monitoring the optical signal directed to the second waveguide and adjusting the electrical current supplied to the electrode heater based on the optical signal directed to the second waveguide.
12. An optical attenuator for selectively reducing the signal level of an optical signal communicated through a first waveguide comprising:
at least a second waveguide and a third waveguide intersecting the first waveguide to form respective junctions with the first waveguide;
each waveguide formed from materials selected to allow optical signals to communicate therethrough;
the first waveguide having an input and an output;
a respective electrode heater disposed adjacent to each junction;
the electrode heaters operable to heat the respective junction to produce internal reflection which direct a portion of the optical signal in the first waveguide to the second waveguide and another portion of the optical signal in the first waveguide to the second waveguide; and
a heater controller operable to supply an electrical current to at least one electrode heater to selectively adjust the signal level of the optical signal at the output of the first waveguide.
13. The optical attenuator of claim 12 further comprising the second waveguide operable to dump a portion of the optical signal communicated through the first wave guide.
14. The optical attenuator of claim 13 further comprising:
a fiber optic cable coupling an output of the third waveguide with a detector;
the detector operable to determine the signal level of the optical signal communicated through the first waveguide; and
the heater controller operable to receive a signal from the detector corresponding with the signal level of the optical signal communicated through the first waveguide and to vary the electrical current supplied to the electrode heater associated with the second waveguide.
15. The optical attenuator of claim 12 further comprising:
an array of first waveguides disposed on a substrate;
an array of second waveguides and third waveguides disposed on the substrate; and
the second waveguides and the third waveguides intersecting the first waveguides at a selected angle ().
16. A method of forming a dynamic, variable optical attenuator operable to attenuate respective optical signals communicated through a first array of waveguides comprising:
forming a first array of waveguides and a second array of waveguides disposed on a substrate with the waveguides of the first array intersecting the waveguides of the second array at a selected angle () to form respective junctions;
forming a layer of cladding over the waveguides and the respective junctions; and
forming the waveguides and the cladding at least in part from materials selected from the group consisting of polymers and other combinations of monomers which produce internal reflection at the respective junctions in response to thermal optic, electrooptic, magnetooptic or acoustooptic effects.
17. The method of claim 16 further comprising coupling at least one of the waveguides of the second array with a detector to monitor the signal level of an optical signal communicated through at least one of the waveguides of the first array.
18. The method of claim 16 further comprising:
placing an electrode heater adjacent to each junction to heat the associated waveguides to produce the internal reflection;
coupling selected waveguides of the second array with a detector to monitor the signal level of optical signals communicated through the waveguides of the first array;
coupling a heater controlled with the electrode heaters to supply electrical current to the electrode heaters; and
coupling the detector to the heater controller to allow the detector to send a signal to the heater controller to adjust the electrical current supplied to at least one of the electrode heaters.
19. The method of claim 16 further comprising:
placing an electrode heater adjacent to each junction to heat the associated waveguides to produce the internal reflection;
coupling at least a first waveguide of the second array with a detector to tap and monitor the signal level of an optical signal communicated through at least one of the waveguides of the first array;
coupling the electrode heater associated with a junction between the first waveguide of the second array and the at least one waveguide of the second array and the at least one waveguide of the first array with a heater controller; and
coupling the electrode heater associated with a junction between a second waveguide of the first array with the heater controller.
20. The method of claim 15 further comprising:
coupling an optical signal detector with selected waveguides in the secondary;
placing electrode heaters adjacent to each junction to heat the associated waveguides to produce the internal reflection; and
coupling the electrode heaters with a heater controller operable to supply a respective electrical current to each electrode heater.
21. A communication system having a plurality of dynamic, variable optical attenuators, each optical attenuator comprising:
an intrinsically wide band device covering all S-band, C-band and L-band optical signals formed in part by a first array of waveguides and a second array of waveguides;
each waveguide defined in part by a core respectively disposed in a channel formed in a layer of cladding;
each waveguide formed from material selected to allow optical signals to communicate therethrough;
the waveguides of the first array intersecting with the waveguides of the second array at an angle () to form respective junctions; and
a respective electrode heater disposed on the layer of cladding adjacent to each junction for use in heating the junction to attenuate optical signals communicated through waveguides of the first array by directing a selected portion of the optical signals communicated through the waveguides of the first array to selected waveguides of the second array by internal reflection of the optical signals at the respective junctions.
22. An optical attenuator for selectively reducing the signal level of an optical signal communicated through a first waveguide comprising:
at least a second waveguide and a third waveguide intersecting the first waveguide to form respective junctions with the first waveguide;
each waveguide formed from materials selected to provide an intrinsically wide band device covering all S-band, C-band and L-band optical signals;
the first waveguide having an input and an output;
a respective electrode heater disposed adjacent to each junction;
the electrode heaters operable to heat the respective junction to produce internal reflection which direct a portion of the optical signal in the first waveguide to the second waveguide and another portion of the optical signal in the first waveguide to the second waveguide; and
a heater controller operable to supply an electrical current to at least one electrode heater to selectively adjust the signal level of the optical signal at the output of the first waveguide.