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A resonant piezoelectric scanner is developed for high-resolution laser-scanning displays. A novel actuation scheme combines the principle of mechanical amplification with lead zirconate titanate (PZT) thin-film actuation. Sinusoidal actuation with 24 V at the mechanical resonance frequency of 40 kHz provides an optical scan angle of 38.5 degrees for the 1.4-mm-wide mirror. This scanner is a significant step toward achieving full-high-definition resolution (1920 x 1080 pixels) in mobile laser projectors without the use of vacuum packaging. The reported piezoscanner requires no bulky components and consumes < 30-mW power at maximum deflection, thus providing significant power and size advantages, compared with reported electromagnetic and electrostatic scanners. Interferometry measurements show that the dynamic deformation is at acceptable levels for a large fraction of the mirror and can be improved further for diffraction-limited performance at full resolution. A design variation with a segmented electrode pair illustrated that reliable angle sensing can be achieved with PZT for closed-loop control of the scanner. [2012-0116]

A comb-actuated torsional microscanner is developed for high-resolution laser-scanning display systems. Typical torsional comb-drive scanners have fingers placed around the perimeter of the scanning mirror. In contrast, the structure in this paper uses cascaded frames, where the comb fingers are placed on an outer drive frame, and the motion is transferred to the inner mirror frame with a mechanical gain. The structure works only in resonant mode without requiring any offset in the comb fingers, keeping the silicon-on-insulator-based process quite simple. The design intent is to improve actuator efficiency by removing the high-drag fingers from the high-velocity scanning mirror. Placing them on the lower velocity drive frame reduces their contribution to the damping torque. Furthermore, placement on the drive frame allows an increase of the number of fingers and their capacity to impart torque. The microscanner exhibits a parametric response, and as such, the maximum deflection is found when actuated at twice its natural frequency. Analytical formulas are given for the coupled-mode equations and frame deflections. A simple formula is derived for the mechanical-gain factor. For a 1-mm × 1.5-mm oblong scanning mirror, a 76° total optical scan angle is achieved at 21.8 kHz with 196-V peak-to-peak excitation voltages.

A novel microelectromechanical systems (MEMS) actuation technique is developed for retinal scanning display and imaging applications allowing effective drive of a two-axes scanning mirror to wide angles at high frequency. Modeling of the device in mechanical and electrical domains, as well as the experimental characterization is described. Full optical scan angles of 65deg and 53deg are achieved for slow (60 Hz sawtooth) and fast (21.3 kHz sinusoid) scan directions, respectively. In combination with a mirror size of 1.5 mm, a resulting thetasopt D product of 79.5 degmiddotmm for fast axis is obtained. This two-dimensional (2-D) magnetic actuation technique delivers sufficient torque to allow non-resonant operation as low as dc in the slow-scan axis while at the same time allowing one-atmosphere operation even at fast-scan axis frequencies large enough to support SXGA (1280 times 1024) resolution scanned beam displays

A novel bending flexure spring design is presented, providing linear stiffness for large rotations of a suspended body. Over 98% linear motion for up to ±7° mechanical scan angle is achievable with the new suspension design.

Several high performing PZT-actuated MEMS laser scanners utilizing mechanical coupling are designed, fabricated, and characterized. Optical angles up to 59.3 deg. and θ opt D·fn-products up to 3052 deg.·mm·Hz are demonstrated. These are the highest performing MEMS scanners in the literature. An angle sensor is integrated into one scanner design without any additional processing. The sensor response shows a linear relationship with the mirror rotation. A closed-loop drive was demonstrated using the scanner output.

A series of compounds containing the −NUN− group has been prepared. Their physical and chemical properties are reported. They adopt a trans configuration, and are thermally robust. The chemistry of some recently-prepared OUN− compounds is also described. These are the first examples of stable analogs of the uranyl ion UO22+. The factors that determine their stability are discussed.

A high frequency resonant torsional microscanner actuated with thin film PZT is modeled, fabricated, and characterized. Sinusoidal actuation with 24 V at a mechanical resonance frequency of 39870 Hz provides a total optical scan angle of 38.5 deg. for the 1.4 mm wide mirror. It provides significant power and size advantages compared to electromagnetically and electrostatically actuated scanners. This scanner is a significant step towards achieving full HD resolution with mobile laser projectors.

A high-frequency novel torsional MEMS scanner is developed for high resolution microdisplays employing a multi-frame geometry. For the torsional mirror, 26.7° and 36.1° total-optical-scan-angle are achieved at resonance, at atmospheric pressure and vacuum respectively.

A comb-actuated rotary MEMS stage with a novel spring structure to achieve linear spring stiffness is presented. The present stages can at resonance rotate ±7deg. and ±4.5deg at vacuum and ambient pressure, respectively.

In this paper, a nonlinear mathematic model for Microvision's MOEMS scanning mirror is presented. The pixel placement accuracy requirement for scanned laser spot displays translates into a roughly 80dB signal to noise ratio, noise being a departure from the ideal trajectory. To provide a tool for understanding subtle nonidealities, a detailed nonlinear mathematical model is derived, using coefficients derived from physics, finite element analysis, and experiments. Twelve degrees of freedom parameterize the motion of a gimbal plate and a suspended micromirror; a thirteenth is the device temperature. Illustrations of the application of the model to capture subtleties about the device dynamics and transfer functions are presented.

The applicability of MOEMS scanning mirrors towards the creation of "flying spot" scanned laser displays is well established. The extension of this concept towards compact embedded pico-projectors has required an evolution of scanners and packaging to accommodate the needs of the consumer electronics space. This paper describes the progression of the biaxial MOEMS scanning mirrors developed by Microvision over recent years. Various aspects of the individual designs are compared. Early devices used a combination of magnetic quasistatic actuation and resonant electrostatic operation in an evacuated atmosphere to create a projection engine for retinal scanned displays. Subsequent designs realized the elimination of both the high voltage electrostatic drive and the vacuum package, and a simplification of the actuation scheme through proprietary technical advances. Additional advances have doubled the scan angle capability and greatly miniaturized the MOEMS component while not incurring significant increase in power consumption, making it an excellent fit for the consumer pico-projector application. The simplicity of the scanned laser-based pico-projector optical design enables high resolution and a large effective image size in a thin projection engine, all of which become critical both to the viability of the technology and adoption by consumers. Microvision's first scanned laser pico-projector is built around a MOEMS scanning mirror capable of projecting 16:9 aspect ratio, WVGA display within a 6.6 mm high package. Further evolution on this path promises continued improvement in resolution, size, and power.

The redox chemistry of the couple formed by XeF[sup +] and elemental xenon gives rise to a green intermediate. This is formed, for example, from XeF[sup +]Sb[sub 2]F[sub 11][sup [minus]] in antimony pentafluoride solution, irreversibly under the action of various reducing agents (e.g. H[sub 2]O, Pb, Hg, SO[sub 2], PF[sub 3], or SbF[sub 3]) or reversibly under the action of xenon gas, and while an overpressure of xenon is maintained, it is long-lived at ambient temperatures. The product has been characterized by a combination of ESR, UV-visible, and Raman spectroscopies, enrichment in [sup 136]Xe or [sup 129]Xe playing a crucial role in establishing that the carrier of the green coloration is the dixenon(1+) cation, Xe[sub 2][sup +]. Quantitative studies of the UV-visible and Raman spectra of antimony pentafluoride solutions imply that the reversible formation of Xe[sub 2][sup +] takes place in accordance with the equilibrium 3Xe + XeF[sup +]Sb[sub 2]F[sub 11][sup [minus]] + 2SbF[sub 5] [r reversible] 2Xe[sub 2][sup +]Sb[sub 2]F[sub 11][sup [minus]], although a secondary equilibrium finds the Xe[sub 2][sup +] bound in a complex with an excess of the oxidant: Xe[sub 2][sup +]Sb[sub 2]F[sub 11][sup [minus]] + XeF[sup +]Sb[sub 2]F[sub 11][sup [minus]] [r reversible] Xe[sub 2][sup +]Sb[sub 2]F[submore » 11][sup [minus]][center dot]XeF[sup +]Sb[sub 2]F[sub 11][sup [minus]]. The spectroscopic properties of Xe[sub 2][sup +] are discussed in relation to those of the isoelectronic species I[sub 2][sup [minus]] and to the results of previous theoretical calculations. Of the media investigated to date antimony pentafluoride seems to be unique in its ability to support the Xe[sub 2][sup +] cation in appreciable concentrations at normal temperatures.« less

This paper describes the design, fabrication, and characterization of the first MEMS scanning mirror with performance matching the polygon mirrors currently used for high-speed consumer laser printing. It has reflector dimensions of 8mm × 0.75mm, and achieves 80° total optical scan angle at an oscillation frequency of 5kHz. This performance enables the placement of approximately 14,000 individually resolvable dots per line at a rate of 10,000 lines per second, a record-setting speed and resolution combination for a MEMS scanner. The scanning mirror is formed in a simple microfabrication process by gold reflector deposition and patterning, and through-wafer deep reactive-ion etching. The scanner is actuated by off-the-shelf piezo-ceramic stacks mounted to the silicon structure in a steel package. Device characteristics predicted by a mathematical model are compared to measurements., NA

Two-axis gimbaled scanner used in an SVGA display product with 58deg optical scan angle, 1.5 mm mirror size, and 21 KHz resonant frequency is reported. Scanner is actuated electromagnetically using a single coil on the outer frame and by mechanical coupling of outer frame motion into the inner mirror frame

A novel MEMS actuation technique has been developed for scanned beam display and imaging applications that allows driving a two-axes scanning mirror to wide angles at high frequency. This actuation technique delivers sufficient torque to allow non-resonant operation as low as DC in the slow-scan axis while at the same time allowing one-atmosphere operation even at fast-scan axis frequencies great enough to support SXGA resolutions. Several display and imaging products have been developed employing this new MEMS actuation technique. Exceptionally good displays can be made by scanning laser beams much the same way a CRT scans electron beams. The display applications can be as diverse as an automotive head up display, where the laser beams are scanned onto the inside of the car’s windshield to be reflected into the driver’s eyes, and a head-worn display where the light beams are scanned directly over the viewer’s vision. For high performance displays the design challenges for a MEMS scanner are great. The scanner represents the system’s limiting aperture so it must be of sufficient size; it must remain flat to fractions of a wavelength so as to not distort the beam’s wave front; it must scan fast enough to handle the many millions of pixels written every second; and it must scan in two axes over significant angles in order to “paint” a wide angle, two-dimensional image. Using the new actuation method described, several MEMS scanner designs have been fabricated which meet the requirements of a variety of display and imaging applications.

A chart review of the most recent home visits from nursing, social work, and clergy to 37 home hospice patients indicated that all but two psychosocial and spiritual issues examined were addressed by hospice staff on home visits. Spirituality and, secondly, death anxiety were the most frequently discussed variables. Clergy addressed more spiritual issues than the other two professions, and social work addressed more psychosocial issues than the other two professions. These findings underscore the important roles that clergy and social work play on the hospice team, and imply that hospice should make a renewed commitment to psychosocial and spiritual care. [Article copies available for a fee from The Haworth Document Delivery Service: 1-800-342-9678. E-mail address: getinfo@haworth.com]

The crystal structure of the air-stable compound PPh4+[UOCl4{NP(m-Tol)3}]–(m-Tol = C6H4Me-m) shows that it contains a linear (179°) OUN–group, with U–O and U–N distances of 176 and 190 pm respectively, coordinated by four chlorine atoms; the U–O distance is typical of uranyl compounds, and the U–N distance suggests a bond order >2.

The gas phase is well known to be host to homonuclear diatomic cations of the noble gases [1], but condensed phases do not readily support species which are at once so acidic and weakly bound. However, the reaction between elemental xenon and the salt XeF + Sb 2 F 11 − in an antimony pentafluoride medium gives a green product which is long-lived under a pressure of xenon at ambient temperatures [2]. The product has been characterised by a combination of ESR, ultraviolet-visible, and Raman spectroscopies. The effects of 129 Xe-enrichment and computer simulation establish beyond doubt that the Xe 2 + cation is the carrier of the ESR signal, and all the other distinctive spectroscopic features, including resonance Raman effects, can now be satisfactorily attributed to this same species. Moreover, the results can at last be reconciled with the formation of Xe 2 + in accordance with the equilibrium although a secondary equilibrium finds the Xe 2 + bound in a complex with an excess of the oxidant [3]

Two properties of B-convexity are shown to hold for P-convexity: (1) Under certain conditions, the direct sum of two P-convex spaces is P-convex. (2) A Banach space is P-convex if each subspace having a Schauder decomposition into finite dimensional subspaces is P-convex. 0. Introduction. In the previous paper [1] the question of whether all B-convex spaces are reflexive was discussed. The concept of a P-convex space was introduced by C. Kottman [4] as follows: Definition. For a positive integer n, let P(n, X) be the supremum of all numbers r such that there is a set of n disjoint closed balls of radius r inside U(X)= fx: llxll < 11. X is said to be P-convex if P(n, X) < Y2 for some n. Kottman showed that all P-convex spaces are both B-convex and reflexive. Therefore the question "Is there a B-convex space that is not P-convex?" is of interest. Many properties of B-convex spaces are not known for P-convex spaces. In this paper we consider two of these properties and prove partial analogs of them for P-convex spaces: The first property is that direct sums of B-convex spaces are B-convex [2]. The proof of this fact for B-convex spaces rests on the invariance of B-convexity under isomorphism, but it is not known whether P-convexity possesses this invariance. Two partial analogs of the direct sum property are obtained, Theorems 1.3 and 1.5, using Ramsey's theorem of combinatorics. The second property is that a space is B-convex if each subspace having a basis is B-convex [1]. A partial analog of this is proved, Theorem 2.1, using one of the direct sum results. We will use the following characterization of P-convexity from Remark 1.4 of [4]: Let a set of n elements be called 5 separated of order n provided the distance between any two elements of the set is at least &. Then a space X is P-convex if and only if for some positive integer n and some positive number e < 2 there is no 2 e separated set of order n in U(X). Received by the editors July 7, 1971. AMS (MOS) subject classifications (1970). Primary 46B10; Secondary 46B05, 46B15, 05A05.

The 109 experimental students in two introductory microbiology classes, where carefully prepared color film slides supplemented usual instruction, were compared on four end-of-course criteria with 114 control students in conventional classes. A pretest, posttest treatment-by-levels multiple analysis of variance and co-variance (Model I: Fixed Effects) experimental design was used. Experimental subjects were superior in three of four criteria. Each of the four cri teria was most precisely predicted by its corresponding pretest covariable. Students gave highly favorable appraisals to the use of film slides. DESPITE THE rapid increase in research in microbiology, the teaching of basic concepts still presents a problem in many institutions. Visual aids to supplement elementary and secondary sci ence programs are fairly common, but compara tively little effort has been extended by institu tions of higher learning to develop such aids. Some outstanding collections of visual aids have been gathered by individuals working in particular spe cialties, but few collections have been developed for basic courses. The need for visual aids de signed to make microbes and their activities more realistic to individuals of a heterogeneous class constitutes the basis for this study.

A proof of James that uniformly nonsquare spaces are reflexive is extended in part to B-convex spaces. A condition sufficient for non-B-convexity and related conditions equivalent to non-B-convexity are given. The following theorem is proved: A Banach space is B-convex if each subspace with basis is B-convex. 0. Introduction. The notion of a B-convex Banach space was introduced by A. Beck [1], [21 as a characterization of those Banach spaces X having the property that a certain strong law of large numbers holds for X valued random variables. Definition. Let k be a positive integer and e a positive number. X is said to be k, t-convex if for any 1x1, ...* Xkl, Kxi 1 < 19 i = 1, * * * , k, there is some choice of signs 61' * * k so that xk_ 1| < k(l c). X is said to be B-convex if it is k, t-convex for some k and c. Further study of B-convex spaces has been done by R. C. James [61, [71, D. P. Giesy [51 and C. A. Kottman [8]. Giesy showed that B-convex spaces have many of the properties of reflexive spaces. James conjectured that all B-convex spaces are reflexive, and proved the conjecture true for 2, E-convex spaces. Both James and Giesy proved the conjecture true for B-convex spaces having an unconditional basis. Kottman extended James' 2, E-convex proof to a larger subclass, P-convex spaces. Examples are known of spaces which are reflexive but not B-convex. ?1 of this paper adopts a part of James' 2, E-convex theorem to all non-B-convex spaces, presents a condition sufficient for non-B-convexity, and gives related characterizations of non-B-convex spaces, though the conjecture of James remains open. ?2 proves a theorem on B-convexity and subspaces with basis analogous to a theorem of Pekczyn'ski on reflexivity and subspaces with basis. For a Banach space X, U(X) will denote the closed unit ball lx: |lxii < 11 of X. I. Non-B-convexity. In James' proof [6] that 2, E-convex spaces are reflexive, he defines for a Banach space X a sequence of numbers Kn, and shows that if X Received by the editors July 7, 1971. AMS (MOS) subject classifications (1970). Primary 46B10; Secondary 46B05, 46B15.