ABSTRACT
An aperture-scanning technique for determining a two-dimensional light distribution is described. Results are obtained by moving a wedge-shaped, knife-edge aperture and comparing measurements from adjacent scans. The scanning procedure described herein overcomes deficiencies inherent in alternative methods that use a two-dimensional detector array or one-dimensional motion of a knife-edge aperture.
ABSTRACT
Some polarization properties of photopolymers are determined. Photopolymers on a Mylar substrate alter an incoming linearly polarized laser beam to an elliptical polarization. The extinction ratio is of the order of 10:1 for the samples tested. Polarization effects were found to change over different regions of each sample by approximately ±10%. The Mylar substrate alone was found to distort the incoming polarization to a comparable degree.
ABSTRACT
A new nonlinear regression procedure for classical dispersion relations has been developed to represent simultaneously both refractive-index and aborption coefficient data. The technique is applied to experimental data for several solids.
ABSTRACT
The nonlinear amplitude transmittance or amplitude reflectance-to-writing light level dependence of a spatial light modulator (SLM) introduces distortions in the output response. The resulting harmonic and intermodulation distortion levels are computed for a representative SLM at several write light illumination levels. The presence of these distortions in the diffraction pattern of an image is also illustrated experimentally. The need for the technical community to quantify these distortions in a universal manner is stressed.
ABSTRACT
A rotated coordinate system is used to evaluate the irradiance distribution of a Fresnel diffraction pattern. Arbitrary diffracting objects are defined in a bounded input plane. Fresnel patterns for linear chirp functions are simply related to the single-slit pattern. Features of the single-slit pattern are developed for use as optical system design criteria.
ABSTRACT
A hybrid optoelectronic system for Fourier transform measurements of temporal signals is described. The magnitude and phase of the signal transform are system outputs. High resolution spectral analysis operation is accomplished by proper spatially dependent phase corrections equivalent to aperture synthesis. Configurations for 1-D and 2-D input data formats are discussed. The system can process signals with continuous spectral content as well as narrow spectral lines.
ABSTRACT
A number of spherical and cylindrical lens combinations are described to achieve a 1-D image and an optical Fourier transform normal to the imaging direction. Both output distributions must be coplanar. Optical features dealt with are the image and transform magnification, lens separation, and input-to-output plane distance. Variable magnification setups with fixed focal length combinations are given.
ABSTRACT
A 1-D optical Fourier spectrum analyzer system is used to detect fatigue cracks as small as 0.5 microm in titanium test samples. Signatures obtained from scans of reflected laser light diffraction patterns show features linked to the presence of surface cracks. Signature characteristics are preserved without a need for critical focusing or optics-to-sample positioning. Analytic modeling of a crack surface profile is used to explain the primary cause of the observed signature properties.
ABSTRACT
The far-field pattern of light scattered by a small rough metallic surface area is obtained with a coherent optical system and used to quantify roughness measurements of machined surfaces. The distribution is usually anisotropic due to tooling marks. A cylinder lens forms a 1-D transform at favorable angular orientations about the optic axis to circumvent this problem and provides useful spectrum averaging. The integrated Gaussian curve fits to experimentally observed scattered light patterns from individual roughness samples yield an empirical linear relation between a Gaussian width parameter and average roughness height.
ABSTRACT
A new procedure to test and evaluate imaging properties of liquid crystal optical transducers is described. The method involves the observation of temporal histories of image-related Fourier spatial frequency signals and is demonstrated for a grating input. Results show that information on timing of spectrum events can be used to modify coherent light imagery. A comparison of spectral features for two liquid crystal transducer types is given.
ABSTRACT
A linear Sayce grating model is described. Expressions for the Fourier transform spectrum of this general pattern are derived. Several important parameters are identified from the analysis. A number of spectrum signature properties are illustrated by means of a few sample calculations.
ABSTRACT
This paper is Part 2 of a three-part sequence dealing with coherent optical signal processing methods for screening Pap smears. Part 2 is devoted to model analysis and evaluation. A mathematical cell model is established to develop the radial spatial frequency profiles of representative cells F(rho). The quantity rho(2)|F(rho)|(2) is shown to be most effective in bringing out normal/malignant cell transform differences. Photographic contrast and gamma play a major role in amplifying cell discriminant features and reducing the effects of the aperture contribution.
ABSTRACT
The interaction of a directed beam of radiation with an absorber is described using a two-level model. Transmitted light intensities and level populations are treated as functions of temporal and spatial independent variables. The general rate equations are given as partial differential equations. Combinations of material constants are identified as scale parameters and used to express the rate equations in nondimensional form as a hyperbolic partial differential equation in canonical form. One integration yields a time-independent relationship between two transmitted beam intensities at different wavelengths. Several calibration experiments are described to evaluate material parameters.
ABSTRACT
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.
ABSTRACT
Several two-lens systems are considered for imaging an input record with specified magnification and focal lengths. Under certain conditions the total length of each setup from input record to image can be minimized (absolute). Alternately, limiting values of minimum length configurations are determined in the neighborhood of the open endpoints of a range of operation.
