National standards for optical components and practices have been in development since late 1940. In the past 5 years, there has been a noticable increase in the number of people and countries active in this endeavor. This paper reviews the current activities of three organizations which are influential in these activities, the American National Standards Institute (ANSI), the International Standards Organization (ISO), and the United States Department of Defense (DOD).
Good Morning. My topic this morning is entitled, "Legal Implications of Standards." What I would like to do today is try and tie together recent developments in two very diff-erent areas of the law: antitrust, and product liability.
This talk discusses two optical surface quality standards, total integrated scatter (T1S) and the scratch and dig standard (MIL-0-13830A). I begin by using Fourier optics to show that the well known expression, It/I(0) = 4 k2a2, which relates scattered power to rms roughness a, is truly valid only for certain classes of surfaces. Vector scattering theory applied to a more general case shows that in fact optics can measure only a bandwidth limited roughness that can be related to scattered power only if the surface statistics are known. For this reason, the standard should perhaps be regarded as a scattered light standard and not as a surface roughness standard. I conclude by describing our use of a novel optical system to develop an objective measurement technique to aid in the manufacture of the artifacts used to implement the scratch standard.
The surface quality of optics used in an extremely sensitive laser instrument, such as a Ring Laser Gyro (RLG), is critical. This has led to the development of a Variable Angle Scatterometer at the Air Force Wright Aeronautical Laboratories at Wright-Patterson Air Force Base, which can detect low level light scatter from the high quality optics used in RLG's, without first overcoating with metals. With this instrument we have been able to identify damage effects that occur during the typical processing and handling of optics which cause wide variation in subsequent measurements depending on when, in the process, one takes data. These measurements indicate that techniques such as a Total Integrated Scatter (TIS) may be inadequate for standards on extremely low scatter optics because of the lack of sensitivity of the method on such surfaces. The general term for optical surfaces better than the lowest level of the scratch-dig standards has become "supersmooth", and is seen in technical literature as well as in advertising. A performance number, such as Bidirectional Radiation Distribution Function (BRDF), which can be measured from the uncoated optical surface by equipment such as the Variable Angle Scatterometer (VAS) is proposed as a method of generating better optical surface specifications. Data show that surfaces of average BRDF values near 10 parts per billion per steriadian (0.010 PPM/Sr) for 0-(301 = 0.5, are now possible and measurable.
Those of us who design things like to believe that the goal of design engineering is to produce the best product for a given cost. Others, less enlightened, might imply that our goal is to design an acceptable product at the lowest cost. However we approach it, few would disagree that cost/performance trade-offs play a crucial role in design engineering. We will explore how production quantity affects these trade-offs and thus the way we go about designing, specifying, purchasing and/or manufacturing optics.
Many customers for Optical Grade Germanium and Silicon blanks have expressed a need for formal specifications for these products, and several have, indeed, written their own. Blanks have been procured under such individual specifications for many years. The effort to establish industry-wide specifications which will help eliminate quality risks without unduly raising production costs for these materials continues with this paper.
A brief description of the chemical vapor deposition (CVD) manufacturing process for zinc selenide (ZnSe) is given. Some of the known associated material imperfections are described. A useful qualitative visual grading system for ZnSe is briefly described. This system is based on evaluating the three major types of material defects found in commercially available ZnSe. The three parameters considered are inclusions, powder, and clouds. An accurate calorimetric testing method for the absorptivity of ZnSe was used to gather data over a two year period. The results of this study show that the visual grading method is good for initial selection of "laser grade" ZnSe. Also reported is a lower surface absorption (0.0001 per surface) than previously published. The bulk absorption coefficient derived is higher than generally reported for ZnSe. The measured ZnSe bulk absorption coefficients range from 0.0005 to 0.0015 per centimeter, with an average of 0.00095 per centimeter for laser grade material.
This paper deals with standards issued by the U.S. Government and American National Standards Institute, Inc., that can be used to specify the physical, environmental, and spectral properties of thin films coated onto optical surfaces. It also includes other information about coatings that must be considered.
Plastic optics have found widespread use in a variety of optical systems ranging from amateur photographic products to projection television optics and fiber optics. This paper serves to survey the current state-of-the-art in plastic optics and to describe the advan-tages and limitations of their use. Special attention will be paid to injection molded optics.
Since the replication process is a relative newcomer to optical component manufacture, it had to be adopted to existing call-outs of both commercial and military specifications. In the past most marketing activities by replication houses were directed at the technical staff of user companies. The resultant incorporation of replicated elements into the various optical systems tended to be functional and, for the most part, did not conflict with standard specifications. Now that thin film replication has become an accepted mode of fabrication, larger numbers of people with only a cursory understanding of the "replication process" are put into positions where they have to make decisions of its final use. This may conceivably lead to conflicts in specifications since a variety of substrate materials may be involved, requiring very specific heat treating and surface preparations. Unless the document issuing authority is very familiar with these processes, it should refrain from de-tailed work instructions. In most cases it is much more functional to only specify performance and en-vironmental requirements and leave it up to the component manufacturer to select his own process. This paper will attempt to clarify potential areas of conflict.
Single point diamond machining of optics has progressed to the point where it is now a recognized prototype and production manufacturing process for optical components. This paper will compare this process to the more conventional grinding and polishing methods.
The term "large" has specific implications about types of optics and their uses. In this paper large optics are defined and figure, beauty, and blank characteristics are specified with tolerances for each. Because it is useless to discuss specifications for properties that cannot be measured, tests for each specification are described. The specification of a large optic takes far more thought and insight than is the case for small optics because of the high cost and demanding applications of large optics.
The developments in the field of lasers and laser optics have placed increasingly demanding requirements on optical components designed for use in state of the art laser systems. Specifications for these components are often imposed without considering the requirements of the fabricator and can result in excessive costs and lengthened delivery times. The dichotomy of the specifying user and the component fabricator needs to be explored and resolved industry wide.
The stated objectives of this workshop were to establish guidelines related to existing optical specifications and standards, and to address the issue of future trends and needs. The format was that of a panel discussion followed by an open forum.