Various types of polarizing prisms can be made from Calcite, a natural crystal which is useful in a spectral region slightly greater than the Visible. Other crystals can be used for other ranges, but the types of prisms that can be made from them are less numerous. The basic types are reviewed, and the restrictions imposed by the optical properties of the materials are discussed. Other polarization components made from birefringent crystals, such as retarders and scramblers are also discussed.
Enhanced stability of PVA-iodine type polarizers can be effected through esterification of the PVA matrix with boric acid. The extent of esterification, and hence stability, can be greatly influenced by reaction conditions. Conditions examined in this study, and their relative influence, include reaction time and temperature, concentration of the boric acid, pH of the reaction medium, and the reaction medium itself.
A generalized optical model for wire grid polarizers is derived based on the form birefringence of composite media of either parallel slabs or cylinders. It is shown that a wire grid polarizer can be represented by a thin sheet of uniaxially anisotropic material with complex refractive indices. This model also applies to sheet polarizers.
This paper presents a study of the hydrolytic stability of high contrast polyvinyl alcohol-iodine type polarizers. The central topic is the relationship between visible light transmission, polarization efficiency and their effect on hydrolytic stability. The format includes a series of graphs, illustrating first the dependence of polarization efficiency on visible light transmission. The spectral distribution of transmitted light before and after hydrolytic stability conditioning is also discussed. Of particular interest is the transmission dependence of hydrolytic stability. This is first presented as the rate of degradation in polarization efficiency as a function of conditioning time for selected transmissions. This data is then presented in a more condensed form. These graphs will illustrate the time required for polarization efficiency degradation to 90% of initial efficiency as a function of visible light transmission and temperature. A new generation of American Hoechst Corporation Film Division polarizers exhibit improved hydrolytic stability. Their performance will be compared with other polyvinyl alcohol-iodine liquid crystal display polarizers.
Thin metal films have been fabricated by vacuum evaporation, which polarize transmitted light at near-infrared and visible wavelengths. Polarization of normal-incidence light was observed for silver, gold and copper films made by this technique. The polarizing films were produced by directing a beam of metal atoms onto the smooth surface of an optically transparent substrate at a large angle of incidence. The film structure revealed by electron-microscope examination is a dense array of parallel metal whiskers aligned opposite the direction of the incident metal atom beam. Polarization is produced by the hertzian parallel-wire effect, which is also the polarization principle of the conventional wire-grid polarizer. The resulting polarizer material can be produced in sheet form or applied as a coating to optical elements.
In 1969 at Sandia Laboratories, optical transparency was achieved in lead zirconate-titanate ferroelectric ceramics by substituting moderate amounts of the element lanthanum (8-12%) for lead. These compositions exhibit the quadratic (Kerr) electrooptic effect. The excellent optical qualities of these materials (designated PLZT) has permitted the practical utilization of their electrooptic properties in a number of devices. All of these devices utilize the classic Kerr cell arrangement. A PLZT wafer with optical axis oriented at 45° with respect to the axes of polarization is sandwiched between crossed polarizers. Since the PLZT material is optically isotropic in the zero field state, the crossed polarizers provide the "OFF" or closed state and large "ON/OFF" contrast ratios may be achieved.
A PLZT electrooptic filter is being used to control the intensity of light transmitted to a video camera from samples undergoing pulsed electron beam thermal testing. This electron beam test system is part of a materials development program for fusion energy applications. During the testing, sample surface temperatures may reach 3000°C and the intense light from these pulses is potentially damaging to the camera. The use of a variable density electrooptic filter prevents this damage and provides improved image quality during rapid changes of surface temperature.
A PLZT Reflection Modulator has been developed for single fiber bidirectional transmission. This coupler approach will allow low power (<0.2 W), small size, and remote modulation (<50 KHz) of optical signals. Potential applications are optical monitoring in hazardous environments, fiber optic sensors, and optical switching.
Electro-optic shutter devices employing lead lanthanum zirconate titanate (PLZT) ceramics and linear dichroic polarizers have been adapted for viewing stereoscopic displays generated both by NTSC compatible video techniques and by computer driven displays. Numerous recent improvements have been made in the fabrication and operating characteristics of PLZT electro-optic shutters. Integration of the PLZT electro-optic shutters into human engineered systems has also evolved. Significant engineering advances relating to PLZT electro-optic shutters are presented and are discussed in terms of their impact on the design and operation of current and future stereoscopic display systems.
Lead lanthanum zirconate titanate (PLZT) shutters have been developed and proposed for several military and industrial applications. To achieve electronic simplification in the control circuitry it is desirable to lower the voltage operating level to less than 600 volts, and to minimize logistic problems relating to spare lens inventories it is desirable to produce shutters with a relatively constant operating voltage. Experimental data is presented for a number of electrode gap/PLZT wafer thickness ratios which indicate that this 600 volt maximum can be attained. A procedure is then described whereby manufactured shutters or lens assemblies can be electroded to operate over a narrow voltage range.
Proc. SPIE 0307, Light Transmission Characteristics Of A High Density Electro-Optical Light Gate Array Based On Lead Lanthanum Zirconate Titanate (PLZT) Ceramics, 0000 (17 May 1982); doi: 10.1117/12.965907
The requirement for high gate densities, together with the necessity to limit the driving voltage of the gates, leads to gate configurations with unfavorable gate width to material thickness ratios. This results in a nonuniform field distribution between the electrodes and in halfwave voltages significantly higher than calculated from the average halfwave fields known from wider gate configurations. This paper sums up some results of light transmission tests and discusses the light transmission conditions as function of the gate geometry.
Several types of liquid crystal devices need polarizers to be able to perform their function properly. The plastic sheet polarizers used for this application are fairly complex layer systems and, more often than not, the problems that result from a wrong understanding of the nature of polarized light or from inappropriate handling of the material are underestimated. This paper is a summary of the properties and construction of plastic sheet polarizers. It explains why the various layers are there and how the user can check quickly if the material he receives does satisfy his needs.
This paper addresses the application of Raman scattering from liquid water molecules to the remote sensing of subsurface ocean temperature. Polarization Raman spectroscopy has been shown to produce the most accurate subsurface measurements if depth penetration of more than one attenuation length is required. A unique two channel receiver, with large diameter circular polarizers, is described.
Ocular counterrolling (OCR) and torsion refer to twisting eye movements that rotate the eyes about the line of sight. OCR is useful in assessing the activation of the gravito-inertial sensors (otoliths) of the inner ear (vestibular system). Information on otolith function is used in medical and experimental work on human orientation. As valuable as this information is, continuous measurement of OCR is still not readily available. This paper describes a method of continuously measuring OCR using polarized light, a system of polarizers and a contact lens. A polarized hard contact lens is placed between two soft lenses and caused to adhere to the eye by soaking in deionized water. The phase difference between the incident rotating polarized light and the reflected light from this lens gives a measure of eye torsion with little contamination from other eye movement modes. Application and performance of this instrument will be discussed.
Instruments used to detect polarized light from astronomical objects are briefly compared. Photoelastic-modulator polarimeters, introduced in 1970, have advantages particularly for extreme-sensitivity measurements of linear and circular polarization, down to the levels 0.01% and below. They have made possible several discoveries. Versions of such instruments for the u.v.-visible and for the infrared (1 - 13μ) are described.
For many years the behavior of collections of optical elements which have the ability to transform the polarization state of light has been studied. These systems not only have been treated as a fundamental problem in optics but have been applied to the development of narrow band filters especially for use in astronomy. Recently it has been shown that collections of such elements can be utilized to transform the temporal shape of short pulses of light. Not only is it possible to transform short pulses into longer distributions but under certain special conditions it is possible to compress pulses temporally. In this paper I will review these achievements beginning with the work of R. Clark Jones and show how an extension of his calculus can be used to formulate optical systems that can be utilized to compress certain optical pulses.
Liquid crystal technology can be applied to the development of alternatives to devices currently used in large high peak power laser systems. This paper explores two such alternatives. One is the use of nematic liquid crystal compounds in place of standard crystalline materials such as quartz and mica, as large aperture waveplates. The other is the use of selective reflection exhibited by the cholesteric class of liquid crystals to construct circular polarizer/optical isolators. The principles of operation, fabrication details, and performance data for both applications are presented.
This paper describes one phase of an ongoing development program in tunable optical filter techniques. Like previous efforts in this program, the goal of this phase is to find practical implementations of sophisticated concepts in birefringent filters. In particular, in this phase we are concerned with a practical implementation of Solc filters. The implementation which is described below incorporates theoretical developments reported previously in a mechanical design suited for laboratory development. In Section 1, a brief introduction to Solc lossless filters is presented. A particular type of lossless filter, the generalized split element, is introduced in Section 2. Its advantages and limitations are noted. The application of waveplates and their engineering implication is described in Section 3. Finally, in Section 4, the actual mechanical and optical components are shown. Attention is given to the relationship between the spectral objectives and the engineering implementation.
Trains of polarizers and retarder elements can be devised to produce nearly any desired color. This paper is concerned with the values of retardation which will produce the largest color contrast between the two positions of parallel and crossed polarizers. The specific systems investigated consist of the case of a retarder between two polarizers and the case of three polarizers and two retarders.
A waveplate is any optical device which retards one polarization component of an incident wave relative to the orthogonal component. This subject is much too general for our purposes so we will restrict the discussion to retardations of one quarter or one half of a wavelength. In particular, we will be concerned with phase retarders which are constant or nearly so over a significant spectral region.