The purpose of this paper is to review the inter-relationships between some critical issues in lens design and the integration of electro-optical systems. It is meant to be of use to the systems engineer responsible for integrating the various disciplines (e.g. optical, thermal, etc.) that make up a full system. It is assumed that the reader has some optical knowledge but is not expert in lens design. The intent is to describe the function of the optical designer and the contribution of optical design programs, to refresh the reader's memory of some important optical issues and relationships, and highlight others that may not be as well known. Representative references are included which the reader can consult to get more detailed information.
The state of the art in visible spectrum solid-state area arrays is discussed from an historical perspective. The major development during the decade of the 1960's was the first demonstration of self-scanned solid-state area imagers using transistors as photosensors. During the decade of the 1970's, major advances included the charge-coupled concept, temporal and spatial noise reduction and the understanding of aliasing vs. MTF. During the 1980's, solid-state imaging has continued to mature with advances in the control of defects, development of color filters for one-chip color camera, development of vertical anti-blooming and anti-smear structures and the use of thin films for vertical photosites.
The noise considerations in staring-mode cameras are different in many respects from those of scanning mode cameras. In this paper some of the features which distinguish staring from scanning mode operation are investigated, and discussed in terms of camera design. A graphical method for predicting camera performance is described and utilized to analyze several hypothetical cameras. The limitations of post processing algorithms used to reduce focal plane array non-uniformity are discussed. The effects of both variations in spectral response and variations in the nonlinearities of the detectors across the array on the post processing algorithms is discussed, and ways of reducing their impact on the image quality are presented. Finally, comparisons are made between cameras operating in different spectral bands with different quantum efficiencies, with the conclusion that, unlike scanning mode cameras, increasing the detector quantum efficiency does not necessarily increase the sensitivity of the cameras.
One of the important factors that affect the performance of aerial image detecting systems is the presence of sensor angular velocities during image recording. The primary contributors to these unwanted angular velocities are: - Velocity of the aircraft relative to the earth. - Low frequency aircraft angular motions. - Vibration induced angular velocities.
A critical survey and current status of transform coding technology is complemented by a review of additional potential improvements. The discussion provides an overview on transform coding technology and assesses the relative importance of the various algorithm classes. The discussed topics include adaptive procedures in both the spatial and transform domains, block size variations and buffering. The importance of preprocessing is reviewed. The conclusions support the view that additional advances in the field are possible and likely to occur.
An overview is presented of digital recording technology for storing electronic imaging system data. Image sensors characteristically produce very high rate data and require very high density storage devices. Of the technologies currently available, magnetic recording represents the only viable techniques for many imaging requirements. The advantage of magnetic recording over competing technologies is expected to continue well into the 1990's. Although optical recording on a tape media is an interesting alternative to magnetic recording, this technology is currently in the research stage and is not expected to be a production technology for some time to come.
The modern electro-optical (E-0) system designer must integrate a data gathering sensor system with a host of other equipment representing various disciplines. This paper provides a systems level overview of the techniques and technologies used in integrating an E-0 data link. The requirements of the data gathering sensor systems and its environment directly impact the synthesis of the various parts of a data link. These parts are described along with some selection analysis and technology thrusts.
Low, medium, and high-level vision algorithms as well as new scene analysis techniques for electro optic sensors are reviewed. Pattern recognition, target detection and object recognition are the applications considered. Applications for electro optic image processing include: ATR, reconnaissance, robotics, inspection, medical image processing, etc. We consider primarily IR and visible imagery, but make note of the need for and increased research in multisensor imaging techniques involving range imagery and multiple wavelength imagery.
The first electro-optical system that generated hardcopy output was the photographic camera. Its invention is generally accredited to the French physicist Joseph Nicephore Niepce (1765 - 1833) who made the first permanent image in the camera obscura, shown in Figure 1. He exposed a light sensitive metal plate in the camera, and then used an engraving process to "fix" the image. This photograph was made 160 years ago in 1826 and still exists today. Fundamentally we are still trying to perform the same function, to transfer a real scene to a hardcopy that can be handled. Since then it has been made faster, with higher resolution , over wider environmental ranges , with an operating requirement of transferring the imaged scene, target or observation to somewhere else for use.
This paper is limited to the soft copy display of electro-optical imagery obtained by reconnaissance systems. The topic is further limited to the author's human factors experience in developing techniques, analyses and procedures which have contributed to the development of soft copy (CRT) displays, having image quality (interpretability) equal or superior to hard copy (film). The results of an early study comparing hard and soft copy by photo interpreters are reviewed. Following this is a description and discussion of various techniques, aids, and analyses which contributed to the results. These include: a discussion of image quality, its measurement, and its visual side; a digital target for measuring a display's potential for high quality presentations; a procedure for determining a display's "best gamma" function; an analytical approach determining a display's size, and pixel spacing and size; and the importance of facility lighting, including some recent experimental data. Finally, an interpretation of the various experiences is given.
Although many of the principles described here may be applied to the performance prediction for a wide variety of electro-optical sensors, the specific types of detectors addressed consist of linear and quasi-linear (TDI) imager based systems which operate in the visible and near-infrared spectrum. By way of background, a brief outline and description of the kinds of sensor systems covered and their modes of operation is presented. This is followed by the description of the techniques applied in arriving at performance predictions.