The present invention provides a method and apparatus for the production and labeling of objects in a manner suitable for the prevention and detection of counterfeiting. Thus, the system incorporates a variety of features that make unauthorized reproduction difficult. In addition, the present invention provides an efficient means for the production of labels and verification of authenticity, whereby a recording apparatus which includes a recording medium, having anisotrophic optical domains, along with a means for transferring a portion of the recording medium to a carrier, wherein a bulk portion of the recording medium has macroscopically detectable anisotrophic optical properties and the detecting apparatus thereon.

Authentication method and system

Introduction to surface topography.- The areal field parameters.- The areal feature parameters.- Areal filtering methods.- Areal form removal.- Areal fractal methods.- Choosing the appropriate parameter.- Characterization of individual areal features.- Multi-scale signature of surface topography.- Correlation of areal surface texture parameters to solar cell efficiency.- Characterisation of cylinder liner honing textures for production control.- Characterization of the mechanical bond strength for copper on glass plating applications.- Inspection of laser structured cams and conrods.- Road surfaces.

Characterisation of Areal Surface Texture

An image processing apparatus for tracking faces in an image stream iteratively receives an acquired image from the image stream including one or more face regions. The acquired image is sub-sampled at a specified resolution to provide a sub-sampled image. An integral image is then calculated for a least a portion of the sub-sampled image. Fixed size face detection is applied to at least a portion of the integral image to provide a set of candidate face regions. Responsive to the set of candidate face regions produced and any previously detected candidate face regions, the resolution is adjusted for sub-sampling a subsequent acquired image.

Real-time face tracking in a digital image acquisition device

Interference microscopy plays a central role in noncontact strategies for process development and quality control, providing full 3D measurement of surface characteristics that influence the functional behavior of manufactured parts. Here I briefly review the history and principles of this important technique, then concentrate on the details of hardware, software, and applications of interference microscopy using phase-shifting and coherence scanning measurement principles. Recent advances considered here include performance improvements, vibration robustness, full color imaging, accommodation of highly sloped surfaces, correlation to contact methods, transparent film analysis, and international standardization of calibration and specification.

Principles of interference microscopy for the measurement of surface topography

Thin-film optical filters, 3rd Edition

When applied to the measurement of smooth surfaces, coherence scanning interferometry can be described by a three-dimensional linear filtering operation that is characterized either by the point-spread function in the space domain or equivalently by the transfer function (TF) in the spatial frequency domain. For an ideal, aberration-free instrument, these characteristics are defined uniquely by the numerical aperture of the objective lens and the bandwidth of the illumination source. In practice, however, physical imperfections such as those in lens aberrations, reference focus, and source alignment mean that the instrument performance is not ideal. Currently, these imperfections often go unnoticed as the instrument performance is typically only verified using rectilinear artifacts such as step heights and lateral grids. If an object of varying slope is measured, however, significant errors are often observed as the surface gradient increases. In this paper, a new method of calibration and adjustment using a silica micro-sphere as a calibration artifact is introduced. The silica microsphere was used to compute the point-spread and TF characteristics of the instrument, and the effect of these characteristics on instrument performance is discussed. Finally, a straightforward method to correct for phase and amplitude imperfections in the TF is described using a modified inverse filter.

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Coherence scanning interferometry: measurement and correction of three-dimensional transfer and point-spread characteristics.

Light from a light source (4) is directed along a sample path (SP) towards a region of a sample surface (7) and along a reference path (RP) towards a reference surface (6) such that light reflected by the region of the sample surface and light reflected by the reference surface interfere. A mover (11) effects relative movement along a scan path between the sample surface (7) and the reference surface (6). A detector (10) senses light intensity at intervals to provide a series of intensity values representing interference fringes produced by a region of a sample surface. A data processor (32) receives first intensity data comprising a first series of intensity values resulting from a measurement operation on a surface area of a substrate and second intensity data comprising at least a second series of intensity values resulting from a measurement operation on a surface area of a thin film structure. The data processor (32) has a gain determiner (100) that determines a gain for the or each thin film of a thin film structure and a surface characteristic determiner (101) that determines a substrate surface characteristic on the basis of the first intensity data, that determines an apparent thin film structure surface characteristic on the basis of the second intensity data, and that modifies the apparent thin film structure surface characteristic usingthe substrate surface characteristic and the gain or gains determined by the gain determiner.

Apparatus for and a method of determining surface characteristics

This paper considers coherence scanning interferometry as a linear filtering operation that is characterised by a point spread function in the space domain or equivalently a transfer function in the frequency domain. The applicability of the theory is discussed and the effects of these functions on the measured interferograms, and their influence on the resulting surface measurements, are described. The practical characterisation of coherence scanning interferometers using a spherical reference artefact is then considered and a new method to compensate measurement errors, based on a modified inverse filter, is demonstrated.

Application of linear systems theory to characterize coherence scanning interferometry

Coherence Scanning Interferometry (CSI), which is also referred to as scanning white light interferometry, is a well-established optical method used to measure the surface roughness and topography with sub-nanometer precision. One of the challenges CSI has faced is extracting the interfacial topographies of a thin film assembly, where the thin film layers are deposited on a substrate, and each interface has its own defined roughness. What makes this analysis difficult is that the peaks of the interference signal are too close to each other to be separately identified. The Helical Complex Field (HCF) function is a topographically defined helix modulated by the electrical field reflectance, originally conceived for the measurement of thin film thickness. In this paper, we verify a new technique, which uses a first order Taylor expansion of the HCF function to determine the interfacial topographies at each pixel, so avoiding a heavy computation. The method is demonstrated on the surfaces of Silicon wafers using deposited Silica and Zirconia oxide thin films as test examples. These measurements show a reasonable agreement with those obtained by conventional CSI measurement of the bare Silicon wafer substrates.

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Measurement of thin film interfacial surface roughness by coherence scanning interferometry

In respective measurement operations on a first sample surface area having a layer structure ( 81 ) and a characterised second sample surface area ( 82 ), light reflected by the region of the sample surface and the reference surface interfere and a sensing device ( 10 ) senses light intensity representing interference fringes at intervals during the relative movement along a measurement scan path to provide first intensity data in the form of a first series of intensity values resulting from a measurement operation on the first sample surface area and second intensity data in the form of a second series of intensity values resulting from a measurement operation on the second sample surface area. A layer structure determiner ( 100 ) determines a frequency transform ratio corresponding to a ratio between the first and second intensity data and fits a layer structure model having variable model parameters related to the layer thicknesses and refractive indices of the layers of a layer structure to the determined ratio by adjusting the model parameters, thereby obtaining for the model parameters values representing the layer thicknesses and refractive indices of the layers of the sample layer structure.

Daniel Ian Mansfield

Papers

Coherence scanning interferometry: measurement and correction of three-dimensional transfer and point-spread characteristics.

Apparatus for and a method of determining surface characteristics

Application of linear systems theory to characterize coherence scanning interferometry

Measurement of thin film interfacial surface roughness by coherence scanning interferometry

Apparatus for and a method of determining a characteristic of a layer or layers