Shutter Type Research Articles

CO2 laser pulse shortening by laser ablation of a metal target

A repeatable and flexible technique for pulse shortening of laser pulses has been applied to transversely excited atmospheric (TEA) CO(2) laser pulses. The technique involves focusing the laser output onto a highly reflective metal target so that plasma is formed, which then operates as a shutter due to strong laser absorption and scattering. Precise control of the focused laser intensity allows for timing of the shutter so that different temporal portions of the pulse can be reflected from the target surface before plasma formation occurs. This type of shutter enables one to reduce the pulse duration down to ~2 ns and to remove the low power, long duration tails that are present in TEA CO(2) pulses. The transmitted energy is reduced as the pulse duration is decreased but the reflected power is ~10 MW for all pulse durations. A simple laser heating model verifies that the pulse shortening depends directly on the plasma formation time, which in turn is dependent on the applied laser intensity. It is envisaged that this plasma shutter will be used as a tool for pulse shaping in the search for laser pulse conditions to optimize conversion efficiency from laser energy to useable extreme ultraviolet (EUV) radiation for EUV source development.

Note: Fast, small, and low vibration mechanical laser shutters

We present three novel mechanical laser shutter designs based, respectively, on a stepper motor, a relay, and a piezoelectric actuator. Each shutter type is ideally suited to a specific shuttering application. The stepper motor is well suited for applications requiring low vibrations, the relay is compact and capable of rapid bursts, and the piezoelectric is 2 orders of magnitude faster than other available mechanical shutters.

Design of a fast rotational chopper for X-ray pump–probe experiments at Diamond Light Source

New trends in X-ray crystallography are concerned with the study of transient conditions of atomic structures, which take place after an energy activation agent is introduced. These time-resolved experiments require a fast mechanical shutter to interrupt the X-ray beam in a pump–probe cycle, with the aim to generate a stroboscopic effect. Thus, only diffraction data that are representative of the activated structure are actually collected. A rotating type of shutter, also known as chopper, is presented with the purpose to enable time-resolved experiments to be performed at I19 small-molecule single-crystal diffraction beamline. Exceptional stability in the rotational speed is critical to achieve the desired stroboscopic effect with minimum jitter. This requirement can be addressed only through design by the specification of suitable components and implementation of high-precision methods in manufacturing. The proposed equipment is comprised of a spindle supported on air bearings coupled to a slotted disc rotating inside a vacuum enclosure and driven by a brushless servo motor. Advanced control features are proposed to ensure that speed stability is achieved. Preliminary tests produced very encouraging results, giving strong indication that the chopper satisfies the specifications required for time-resolved experiments.

Standardized Collimated Beam Testing Protocol for Water/Wastewater Ultraviolet Disinfection

Ultraviolet (UV) irradiation has emerged as a viable alternative for water/wastewater disinfection. Laboratory dose-response data from collimated-beam tests are commonly used as a basis for determining the necessary delivered UV dose for full-scale UV systems as measured by UV intensity and exposure time. While researchers often think that germicidal dose can be estimated confidently in a collimated beam system, the reported dose-response relationships vary considerably. Numerous factors may affect the test results to some extent. They include apparatus setup, column dimensions, UV lamp type and output, intensity measurement, shutter type and operation, petri dish specifications, sample volume and depth of the liquid, mixing condition, laboratory settings, microbial organism preparation and testing, and water quality. The methodology used to calculate the UV dose for collimated beam tests is also a critical factor. To ensure reproducibility or to have a meaningful comparison of results from different collimated beam tests, a standardized protocol for collimated beam testing and its dose calculation is necessary. The standardized collimated beam test can then serve as a tool to calibrate the dose calculation models for field-scale UV reactors and, consequently, to meaningfully compare the dose values derived from these models. A comprehensive standardized collimated beam testing protocol is warranted to advance applications of UV disinfection for water/wastewater. However, development of such a protocol is a significant research effort that will require input from researchers of various technical and disciplinary backgrounds. In addition, some technical issues still need to be clarified by further research. This paper presents important issues associated with collimated beam testing in the context of developing a standard protocol as well as future research needs. The main objective is to serve as a starting point for development of a standardized collimated beam testing protocol that is universally acceptable by researchers, industries, and regulatory agencies.

Spatial Light Modulator by Using Polymer Cell-Wall Type Liquid Crystal Optical Shutter

Abstract Polymer Cell-Wall Type Liquid Crystal (PCW-LC) light shutter has been developed. This is a kind of liquid crystal-polymer complexes (LCPCs), utilizing the light scattering of cholesteric focal conic texture. However, its abilities are superior to other LCPCs reported. As the cholesteric liquid crystal grains are covered with thin polymer films, the polymer content is very small, around 10 wt%. Consequently, the driving voltage is very low (Ca. 5–6V). This type of LC light shutter has the great advantage of non-polarizer usage. Therefore, this type of light shutter can be useful for not only liquid crystal display devices but also other applications, for example, spatial light modulator (SLM). In this work, PCW-LC is introduced at first, and then the applications of PCW-LC light shutter to SLM is described. Non-polarizer usage makes it easier to combine it with the other component parts for producing a SLM.

Sound insulation of different types of shutters used in Jordan

Window shutters, which are mainly installed in buildings for thermal accommodation, can provide appreciable external noise insulation. Five widely used types of these shutters were tested in a controlled laboratory environment similar to what might be encountered in the field. These shutters were subjected to a 1 3 octave band noise signal and traffic noise recorded and replayed using an open-close arrangement. Two types of window framing were tested, one with aluminium framing (slide leaves) and the other with plastic framing (openable leaves). The weighted sound reduction index of the window with plastic framing was 35 dB and that for the aluminium framing was 20 dB. The additional insulation provided by these shutters, when installed in front of plastic-framed windows, is in general negligible and only noticeable at high frequencies (above 1 kHz). If these shutters are used with aluminium-framed windows, they provide 10–15 dB of additional sound insulation in the frequency range 31·5 Hz to 8 kHz. Sound insulation of the shutters when the window is open is equal to 14 dB for the wooden shutter, 16 dB for the plastic shutter, 14 dB for the metal with foam shutter, and 20 dB for the plastic with foam shutters. Plastic-framed windows provide an insulation of approximately 37 dB averaged over the frequency range 100 Hz to 8 kHz based on 1 3 octave bands, while aluminium-framed windows provide an average insulation of 24 dB.

A rapid chemiluminescent enzyme-linked immunosorbent assay for cytomegalovirus immunoglobulin G antibodies using instant photographic film

A rapid and convenient chemiluminescent enzyme-linked immunosorbent assay (ELISA) for IgG antibodies to cytomegalovirus has been developed which uses low cost equipment. Assays were carried out on transparent microtitre plates and used an anti-human IgG horseradish peroxidase conjugate. Bound peroxidase was detected chemiluminescently using a p-iodophenol-luminol-peroxide reagent. Light emission from the wells of the microtitre plate was detected on instant photographic film (ASA 20,000) held in a specially designed shutter type camera. The semi-quantitative technique was tested in a routine laboratory for a period of 7 wk and the results obtained compared well (95.3% agreement) with those obtained by a conventional colorimetric ELISA using an alkaline phosphatase label.

Twisted Nematic Liquid Crystal Displays—Development and Technology

General physical properties of Liquid Crystal are outlined. The properties relevant to the display operation of twisted nematic liquid crystal display (TN-LCD) are discussed. Exploitation of dielectric anisotropy of LC molecules in building TN-LCD is brought out. The design procedures with special reference to material properties and LCD cell technology are indicated.A typical production-process-flow adopted for continuously driven TN-LCD fabrication is given. The process simplification and technology change for low-cost LCDs are indicated with special reference to flexible substrate LCD.Colour LCD, using negative mode optical shutter type TN field effect is explained. Principle of guest-host colour LCD is illustrated.

841320 Sampler with a new type of shutter : Eriksson, L G Proc 10th International Conference on Soil Mechanics and Foundation Engineering, Stockholm, 15–19 June 1981V2, P471–474. Publ Rotterdam: A. A. Balkema, 1981

841320 Sampler with a new type of shutter : Eriksson, L G Proc 10th International Conference on Soil Mechanics and Foundation Engineering, Stockholm, 15–19 June 1981V2, P471–474. Publ Rotterdam: A. A. Balkema, 1981

The effect of optical unloading of a passive shutter on the energy parameters of a single-pulse ruby laser

The present paper presents the results of an experimental investigation of the effect of the shutter unloading coefficient on the energy parameters of a ruby laser. The unloading coefficient is understood to mean the ratio between the radiation densities on the shutter surfaces facing one another and the end surface of the active element. The measurements were carried out for two types of shutters: a shutter made of KS-19 glass and a shutter based on a solution of kryptocyanin in ethanol. The chosen shutters have substantially different spectroscopic parameters. The duration ~- of the excited state for KS-19 glass is 10 -? sec [3 ], while for kryptocyanin it is T ~ 10 -10 sec. The absorption cross section a s at the ruby lasing wavelength is estimated to be ~ 6 �9 10 -19 [3] and 4.10 -16 cm 2 respectively. The majority of other known media for passive shutters haveparameterswh ich fall in the interval between the indicated values. Since ~s is much greater than the absorption cross section of ions in ruby (ar = 2.5.10 -20 cm2), it follows that for Unloading of the shutter one-pulse lasing may be observed within certain limits [4]. The relative optical unloading of the shutter was accomplished by means of a telescopic system. The scattering component of the telescope was a concave spherical surface (R l = 127.6 mm) implemented using the end-face of the active element. A rod having a diameter of 10 mm and a length of the active portion equal to 120 mm was used; its surface was of the matte type. An iris 5 mm in diameter which isolated the uniformly pumped region of the ruby was mounted flush against the spherical surface. The second component of the telescopic system consisted of changeable plane-concave lenses made of K-8 glass which were mounted in optical contact with the shutter made of KS-19 glass or with the window of the vessel if a solution of kryptocyanin was used as the shutter. The lenses used had focal distances of 254, 354, 516, and 685 mm. The resonator was formed by a stack of two glass plates and a dielectric mirror having a reflection coefficient close to unity. The initial transmission of both types of shutter was chosen to be identical and equal to 0.25. The distance between the telescope components at which the lasing energy was maximal was selected for each removable lens, and the duration of the lasing was determined in this portion of the telescopic system. The values of the unloading coefficient of the shutter were 2.5, 5, 10, and 20 in the tests. The pumping was identical and equal to 600 J in all cases.

The Stressed-Plate Shutter, a New Moderate-Speed Electro-Optical Light Modulator

A new electro-optical shutter system is described which functions by virtue of uniform photoelastic birefringence induced mechanically by piezoelectric means into a glass plate supported between suitably oriented linear polarizers. The basic principles of operation of this stressed-plate shutter are explained in terms of its use as a moderate-speed capping shutter. The suitability of various materials for each of the major mechanical and optical components of the shutter is considered. Design parameters and performance characteristics are given for a working model shutter constructed to demonstrate the system concept. It is shown that, in its present state of development, this type of shutter is capable of closing a 5-cm aperture to an optical density of 3 within 250 μsec of receipt of a triggering electronic signal.

Photographic Techniques in Jet Propulsion Studies

Motion picture photography has become a standard tool for obtaining permanent records of certain phases of jet engine firings. Types of motion picture cameras generally used are discussed here. They have been classified into five categories based on frame frequency or linear film speed. Representative commercially available cameras are reviewed with regard to frame frequency, motor drive, shutter type, special features, etc. Methods generally used to modify test engines to make them amenable to photographic techniques are described. Systems for correlating events with photographs and comments on interpretation of results are presented briefly. A bibliography is appended for the investigator who desires more extensive details.

The Operation and Photographic Characteristics of a Kerr-cell Type of Electro-optical Shutter

A Kerr-cell electro-optical shutter is described, the shutter action being controlled by a high voltage pulse applied to the cell electrodes. The exposure time used is 2×10-6 second, and provision is made for obtaining `delayed' exposures up to times of the order of 10-4 second. The photographic limitations of the shutter are discussed and the formation of the image considered in some detail. The assumptions necessary for a quantitative photometric analysis of Kerr-cell exposures are stated and an approximate limit is set on the magnitude of errors resulting from such assumptions. The applications of the Kerr-cell technique to the measurement of particular spark channel characteristics are also described.

Camera Shutters*

An extensive program of research into characteristics of shutters, begun in 1941, has resulted in a series of definitions and test methods for between-lens and focal-plane type shutters which have been adopted by the ASA. The characteristics of these two types of shutters, and of louvre shutters, are reviewed, and the important distinction between effective exposure time and actual (or motion-stopping) exposure time in these two shutter types is clarified. The oscillographic test method for between-lens shutters is described and depicted via photograph and schematic diagram. The strobotac and drum tester method for focal plane shutters are summarized, as is a method for testing louvre shutters.The effect of inefficient between-lens shutters on optical performance, effect of a glass pressure plate on efficiency of focal-plane shutters, and equations for the two types of distortion caused by focal plane shutters are discussed. The utilization and advantage of shutter speed in aerial cameras to reduce the deteriorative effects upon definition caused by forward aircraft speed, angular motion of the aircraft about its axis, and camera vibration are discussed.The shutterless strip camera and the corollary principle of image speed compensation with moving-film magazines in conventional cameras, and the potentialities of this important new development, are described.The impetus of wartime necessity resulted in development of several new shutters, improvements in others, and consideration of many more types. The Langer multiple-slit focal plane shutter, shutters based on birefringent phenomena, multiple-disk between-lens shutters are considered. Shutter leaves of Be-Al alloy were tried, with conspicuous success. The work done by Mitchell in doubling the speed of the 6-in. K-17 shutter and a detailed analysis of research results obtained in improving the K-22 focal plane shutter are presented.A louvre-shutter for the 48-in. f:6.3×18 lens was built at the Photographic Laboratory. Photographs and a schematic diagram of this high performance shutter are included. A doctrine of tactical usage and development for shutters has been formulated; mapping cameras will continue to use between-lens shutters, as will night cameras, but the very large day reconnaissance camera will use focal plane shutters exclusively. A list of seventeen memorandum reports, which cover in detail the work summarized in this paper, is appended.

The Electrooptical Shutter—its Theory and Technique

This paper records a development in the design of the single cell type of electrooptical shutter together with a theory describing its action. Part I. gives a description of the shutter together with a method of observing simultaneously two stages of the phenomenon being studied. Part II gives the theory of shutter action. A condensed summary of the physical optics is followed by a development of the electric circuit theory which gives the manner of closing of the shutter when the leads to it are fairly short. The theory is illustrated by a series of numerical examples based on typical experimental conditions which show the effect of varying each controlling factor. The times required for closing (90 to 100 percent transmission) are of the order of 4\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}9}$ sec. under favorable conditions. The necessity for a Kerr cell of small electrostatic capacity is shown. Part III gives three groups of experimental data which were obtained with the shutter in a study of spark breakdown: one indicates the time resolution attainable; another gives the total time lag in closing; and a third gives the change in this lag with certain conditions. The information of the second group combined with the theory yields the rate of fall of voltage across the controlling spark gap (static breakdown), a typical value being 14\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}9}$ sec. to fall to 20 percent of the initial value (76 cm Hg, 5 mm gap). The theory and experimental data are found in complete agreement. An improved method is given for the determination of the correct damping resistance in the shutter circuit. Part IV gives a description and the factors considered in the design of the Kerr cells developed in the present study, also the essentials of the technique for their proper use.

An application of the photo-electric cell to a comparison of the efficiencies of photographic shutters

The paper describes a method of comparing the efficiencies of shutters, incorporating photo-electric measurements of the total amounts of light passed by the shutters. Details of an application of the method to a new type of shutter are given.