Solid-state imagers with integrated scanning circuits offer many advantages over beam-scanned camera tubes in cost, reliability, size, and range of applications. Solid-state electrical imagers are the realization of available methods for organizing and transferring charges from an image-sensing area to electrical readout ports. Surface acoustic waves (SAWs) traveling on a piezo-electric medium have been shown to support charge transfer in a solid-state device: charges can be injected into electric potential wells that travel at the acoustic speed and may be collected at a different location on the surface. The principles of SAW charge-transfer devices (SAW-CTDs) are reviewed. Design concepts are presented for SAW-CTDs and CCD-CTDs for use as electrical or optical waveform recorders and as imaging devices, e.g., streak and framing cameras, operating in single-shot and continuously cycling modes.
This paper presents a new positioning technique, called omnidirectional dynamic vision positioning, for use in navigating a mobile robot. A fisheye lens image system is used as an omnidirectional vision device. A positioning algorithm used with reference beacons determines the position of the robot in terms of a global positioning coordinate system. An accuracy analysis was conducted, and positioning errors were characterized. The experimental results verify the practicability and realizability of the new technique. The advantage of omnidirectional vision for navigation is the simplicity of recording an entire 2 tt radian scene without camera scanning.
Polarization differences between subapertures of an optical array can seriously degrade system performance. Experimental data and a theoretical model are presented that show far field performance as a function of relative polarization in a simple Young array.
Experimental and theoretical diffraction intensities are studied for large spherical aberrations ranging from 5X to 50X. In addition, diffractive and geometric rms spot sizes are compared. The experiments and analysis show that for large spherical aberrations there is a core near-axis intensity region that is independent of the aperture radius. This is verified by a stationary phase expansion of the diffraction intearals.
The effect of vignetting on the measured angular light energy distribution in a particle size distribution measuring system is studied theoretically and experimentally. A series of correction charts are produced that allow the vignetted light energy distribution from a homogeneous particle field to be corrected, depending on the position and extent of the particle field with respect to the collection lens. This phenomenon is of great importance in the measure-ment of particle size distribution of systems where (1) the particle field cannot be within the focal length of the collection lens owing to difficulty in optical access, (2) the particle field extent is larger than the required collection lens focal length, or (3) an extended beam path is desirable owing to low concentration of the particles in the field.
A gas-filter correlation spectrometer that employed a wide spectral band of infrared radiation and gas-filter cell has been built and successfully tested to measure methanol concentrations up to 113 ppm. The instrument demonstrates a detection limit of approximately 1.0 um. The interference of nonmethanol gases is negligible when automobile exhausts are used for the test. The most prominent, though not serious, problem appears to be the signal drift, which is believed to be improved by thermally insulating the instrument. The analyzer demonstrated its capability for real-time analysis of emissions from methanol-fueled vehicles due to its simplicity and fast response as compared with wet chemical methods.
A system has been developed to investigate documents that are suspected of having been altered, forged, or erased. The system is based on the fact that each ink and paper has characteristic luminescence properties. Lasers are used to excite luminescence from the document, and the luminescence, along with its spectral distribution, is detected by a set of scanning mirrors that efficiently couple the light to a wavelength selector (monochromator) and photodiodes. Compared to previous systems, this system offers major improvements in sensitivity, versatility, and convenience of operation. These refine-ments are achieved by exploiting the capabilities of the lasers and of digital data processing/acquisition.
A technique is described for the instantaneous measurement of the two-dimensional distribution of the OH radical in spray flames based on planar laser-induced fluorescence. Sheet illumination is used with the resulting fluorescence imaged at 90° onto an intensified photo-diode array camera. Details of the excitation/detection strategy, experimental apparatus, and detection limits are described, and representative results are presented.
A simple method to measure the resolution of digital image input devices is reported. The method, called the curve-fitting method (CFM), is based on a Gaussian impulse response model for the devices and a curve-fitting technique. The advantage of the CFM over the contrast transfer function (CTF) method is its great convenience, especially when a local measurement is intended. The average time of the measurement, which is made by running a curve-fitting program, is about 15 s.
Holograms made using only the phase of an object's Fourier transform (FT) have been demonstrated by others to contain enough information to produce a noisy but recognizable reconstruction. However, no mathematical analysis has been available. In this paper, a theory is developed that explains many features observed in numerical experiments. It was found that splitting the original function into a sum of even and odd parts results in a useful equation for the FT phase. This made it possible for example to see mathematically why edge enhancement occurs and why the phase from one object and the amplitude from another will produce an image of the former. It was also found that zero crossings in the FT of the even part of the input function play a dominant role in determining the nature of a reconstruction.
An improved real-time optical image subtraction method based on the work of Zhao and Liu ["Real-time optical interferometric image subtraction by wave polarization," Appl. Opt. 21, 3864 (1982)] is proposed. A hologram of the beams from a Wollaston prism is recorded and used as an optical element in the system. It is shown that a dark field over a larger area for image subtraction can be obtained with such a system.
Many conventional experimental tunnel test sections are enclosed by metallic cylinders. For optical applications, a relatively inexpensive approach is to replace the metallic test section of the cylinder with a plastic or glass tube. This paper describes several ways to neutralize the cylindrical optical power, and hence the astigmatism, of these transparent tubes. One approach is to enclose the test section in a rectangular tank filled with the tunnel fluid. The outer radius of curvature of the tank neutralizes the residual cylindrical power. Another approach is to use an external cylindrical lens without the tank surface modifications. Finally, an external lens can be employed when the tube-fluid combination is used in air without the tank.
Geometric moments are useful in pattern recognition, and several optical methods have been proposed for their calculation. In this paper, we present a new hybrid optical/digital processor that computes the geometric moments using the recently introduced Hartley transform (HT). This transform has the attractive property of being real when the signal is real. We prove an important result, that all geometric moments of an image can be computed recursively from the various partial derivatives (near origin) of the HT intensity. An analytical example is provided to illustrate the proposed method.
This past year brought a number of changes to Optical Engineering, the most significant of which was the increase in publication frequency from bimonthly to monthly. A few changes were merely cosmetic in nature (e.g., an increase in type size), where-as others were adopted to make the journal more informative' and interesting to the reader (inclusion of reference titles, biographical sketches and photos of authors, etc.). Based on the many positive comments I have received, I am convinced that the majority of readers appreciate these changes and regard them as improvements to the journal.
This book hardly needs an introduction,
since its first edition appeared 17 years ago.
In the mid-1970s I was teaching a course on
optical coatings to a group of optical coating
engineers from various industrial coating
shops. I chatted with engineers from Texas
Instruments who had learned about optical
coatings essentially on their own, with little
tutoring from experienced workers. They
referred to Prof. Macleod's book as their
"bible." While this reviewer does not mean to
imply any irreverent comparison, it still
serves to remind us that Macleod's book has
remained the standard textbook on optical
coatings for nearly two decades. Other books
have appeared during this period, for example,
Z. Knittl's Optics of Thin Films and
more recently H. Pulker's Coatings on Glass.
Although they cover some topics that
Macleod does not, Thin-Film Optical Filters
has remained the standard reference and text
in this field.