Jay Mendelsohn

Screening of cervical cytological samples using coherent optical processing. Part 3

Coherent optical signal processing methods for screening Pap smears were evaluated and are presented in a three-part sequence. In Part 1, 2-D Fourier spectra of normal and abnormal cells generated from many high resolution cell photographs are presented. Each cell spectrum was measured with a coherent optical data processing system containing a special geometry detector and automated data collection capability. Several parameters, determined from weighted measures of the cell transform intensity variations, were tested as feature discriminators to separate normal from abnormal cells. An analysis of the experimental data demonstrates that several transform features are good discriminators of normal/abnormal cells (using standard Baysian decision algorithms with quadratic decision rules). In Part 2, mathematical model studies to guide and validate the experimental work show certain transform parameters to be functionally related to cell and nucleus diameter and optical density. Other parameters appear to be related to cell characteristics such as clumping of nuclear deoxyribonucleic acid (DNA). The model studies also show that the photographic variables play a key role in cell image preprocessing prior to Fourier analysis. Part 3 discusses an optical transducer that was used as a film replacement to modulate a laser beam spatially with a cell image. Several of the feature discriminators used in Part 1 with photographic film images served also to separate normal and malignant cell types when the cell Fourier spectrum was obtained from a transducer image. Based on an understanding of the procedure from the model studies and the demonstrated ability to separate normal and malignant cells using certain transform features, a coherent optical processing system to screen Pap smears from cell or slide photographs is feasible and appears practical in terms of the number of cells to be processed. A high-speed optical transducer would be required for processing large numbers of cells without photography in a reasonable time interval.

Paraxial analysis of light scattering by biological cells in a flow system.

A special mathematical model is developed to find the scattered light pattern of biological cells in a fluid flow system. A paraxial approximation to the diffraction integral is used to accommodate nonspherical and asymmetrical cells. The paraxial approximation results are in good agreement with Mie calculations for homogeneous spheres of comparable size and refractive index. A 2-D fast Fourier transform program is used to simulate variable cell morphology and experimental conditions. Distinct signature differences for two types of cells resembling normal and abnormal malignant human cervical cells are found useful as discriminant features. The ability to handle a variety of model cell shapes and distortions by these methods is demonstrated, and use of signature features for cell discrimination is shown experimentally.

Digital Analysis Of The Effects Of Terrain Clutter On The Performance Of Matched Filters For Target Identification And Location

A digital analysis of the effect of terrain-target interactions on the signal-to-clutter (S/C) ratio of the output of a matched filter is made. Three terrain types (wood-land, village, and roadside) were included in the investigation. A photographic image of an M-60 tank used as the target was digitized (512 x 512 pixels) and a matched filter constructed digitally, using a two-dimensional FFT algorithm. The matched filter was then used to obtain the correlation between the target and the various terrain types to obtain the signal-to-clutter ratio. Various high frequency versions of the matched filter were systematically investigated for possible optimization in the S/C ratio in an attempt to optimize the design which was eventually realized in analog optical form. The computational aspects of the problem, from the point of view of doing digital image analysis on a minicomputer with limited memory, is also discussed.

Robotic Vision, Tray-Picking System Design Using Multiple, Optical Matched Filters

The optical correlator is applied to a robotic vision, tray-picking problem. Complex matched filters (MFs) are designed to provide sufficient optical memory for accepting any orientation of the desired part, and a multiple holographic lens (MHL) is used to increase the memory for continuous coverage. It is shown that with appropriate thresholding a small part can be selected using optical matched filters. A number of criteria are presented for optimizing the vision system. Two of the part-filled trays that Mendelsohn used are considered in this paper which is the analog (optical) expansion of his paper. Our view in this paper is that of the optical correlator as a cueing device for subsequent, finer vision techniques.

Application Of The Matched Filter Image Correlator To IR, SAR, And Visual Target Data

Optical matched filter image correlators (OMFICs) have usually been associated with visual sensors. This paper presents a discussion of OMFIC application to IR, SAR, and visual target data employing a validated digital simulation and/or laboratory experiments to detect, and in some cases track, targets using the three kinds of imagery. Extensive results are presented.

Validation Of A Digital Simulation Of An Optical Matched Filter Correlator Applied To Aerial Reconnaissance

Optical and digital approaches to 2-D image processors each have their unique advantages and limitations. Hybrid systems have been proposed to utilize the best of both. An equally important manner in which the two approaches can complement each other is through a digital simulation of the optical system. This paper reviews some of the problems of matched filter correlator applications and illustrates how valid models for simulations can be generated. Comparisons of the digital simulation to the analog approach are made for detection problems using specific targets and terrains. The relative merits of each technique as well as ways in which the digital simulation may be used to assist in the optimal design of the analog system are discussed.

Multiple Filter Storage

In the field of optical correlation, a number of applications have been demonstrated successfully in the laboratory. As a result, field demonstration models will be constructed soon. These include missle guidance l, word processing2, and film screening3. In each of these applications, and for nearly all other correlator applications, large memory and/or some memory adaptability is necessary for the performance of the designated task.