An analysis of the performance of simple refractive null compensators was done. Two types of correctors were studied--the Dall compensator and the Offner compensator. A framework was built for determining whether these simple null tests are adequate for a wide range of aspheric surfaces. Variables involved in determining a surface to be null tested are f-number, conic constant, and focal length. Examples are given on how to determine the best null test for several aspheric surfaces. Also of concern in the design of a null compensator was simplicity. Two elements were the maximum used for both compensators and all compensator surfaces were spherical.

Throughout their respective bodies of work, both Toni Morrison and Gloria Naylor invoke recurring images of the mirror and the mirror-gazing act. Because of the preponderance of these images and because of how they inform our deeper understanding of character, theme, and genre, I argue that these images constitute an important trope in Morrison and Naylor\'s fiction. Although the mirror trope pervades both writers\' bodies of work, it has not garnered significant scholarly attention, particularly with respect to the ways in which the trope highlights an intertextual dialogue between two essential writers of the 20th century American narrative. In this project, then, I conduct an in-depth but by no means exhaustive exploration into the mirror trope. I am specifically concerned with how each writer brings this trope to bear on issues of representation, the politics of recognition, and the dilemma of black female subjectivity and agency in a racist and misogynistic American society. I argue, then, that because the mirror trope is where patriarchal and racist structures of power collide, it signifies a critical point of intersectionality between race and gender. For that reason, the mirror emerges as a space of contestation within these narratives. / Master of Arts

The degradation of astronomical images caused by atmospheric turbulence will be much more severe in the next generation of terrestrial telescopes and its compensation will require deformable mirrors with up to tens-of-thousands of actuators. Current designs for these correctors consist of scaling up the proven technologies of flexible optical plates deformed under the out-of-plane action of linear actuators. This approach will lead to an exponential growth of cost with the number of actuators, and in very complex mechanisms. This thesis proposes a new concept of optical correction which is modular, robust, lightweight and low-cost and is based on the bimorph in-plane actuation. The adaptive mirror consists of segmented identical hexagonal bimorph mirrors allowing to indefinitely increase the degree of correction while maintaining the first mechanical resonance at the level of a single segment and showing an increase in price only proportional to the number of segments. Each bimorph segment can be mass-produced by simply screen-printing an array of thin piezoelectric patches onto a silicon wafer resulting in very compact and lightweight modules and at a price essentially independent from the number of actuators. The controlled deformation of a screen-printed bimorph mirror was experimentally achieved with meaningful optical shapes and appropriate amplitudes; its capability for compensating turbulence was evaluated numerically. The generation of continuous surfaces by an assembly of these mirrors was numerically simulated and a demonstrator of concept consisting of 3 segments was constructed.

A parametric design study of light weight mirror shapes with various support conditions was performed utilizing the finite element program NASTRAN. Improvements in the mirror performance were made based on the following design criteria: (1) minimization of the optical surface wavefront variations, (2) minimization of the self-weight directly related to cost of manufacturing, and (3) optimal location of support points. A pre-processor to automatically generate a finite element model for each mirror geometry was developed in order to obtain the structural deformations systematically. Additionally, a post-processor, which prepares an input data file for FRINGE (an optical computer code) was developed for generating the optical deflections that lead to the surface wavefront variations. Procedures and modeling techniques to achieve the optimum (the lightest and stiffest mirror shape due to self-weight) were addressed. Fundamental natural frequency analyses, for contoured back mirror shapes for a variety of support conditions, were performed and followed by comparisons of the results which were obtained from NASTRAN and a closed-form approximate solution. In addition, element validity and sensitivity studies were conducted to demonstrate the behavior of the element types provided in the NASTRAN program when used for optical applications. Scaling Laws for the evaluations of the optical performances and the fundamental frequencies were established.

No description available.

QC 351 A7 no. 03 / The problems connected with the utilization of large high -resolution telescopes are concentrated into two principal areas. The first concerns the physical properties of the mirror disc; the second involves the pro- cessing of the mirror in the optical shop. This technical report concerns, 1) the design of a new type of opti- cal polisher, one with a stationary mirror platform, and, 2) the casting of large discs made up of a new type of glass. This new glass, designated type RZ by Owens -Illinois, has a zero coefficient of thermal expansion at 25° Centigrade. A proposal for research in these two areas has already been made. This research has been supported, in part, under Contract ONR -2173- (12) by the Advanced Research Projects Agency and administered by the Office of Naval Research.

In the ancient and medieval period, in the eastern Mediterranean and Near East, writers often use the metaphor of an eye or mirror interacting with the light of the sun to explain humanity’s ability to participate in the presence (or glory) of the divine. In this dissertation, I focus on a particular type of mirror imagery, what I call “the mirror of glory,” from the 2nd to 4th centuries in Greek and Syriac literature, from the extracanonical Odes of Solomon and Acts of Thomas to Plotinus’s Enneads to the writings of Athanasius (d. c. 373) and Ephrem (d. c. 373). I conclude with parallel themes in the later east-Syriac tradition and early Sufism, from John of Dalyatha (d.c. 780) of present-day Iraq to the Qur’anic commentaries attributed to Ja‘far al-Sādiq (d. 148/765). In all these texts, I argue the “mirror of glory” articulates and enacts, for the reader, a convergence in the meeting of gazes between oneself, the divine, and other glorified beings (such as angels), where seers and seen and speakers and spoken to merge in a regenerative encounter. Through examining these writers’ optical theories when possible, I demonstrate how this mirror imagery is predicated upon a link between the soul and the senses. In the highest stages of giving glory, these writers describe an embodied reflexivity that is neither singular (I and I), nor double (I and Thou), but collective (I and We)—a self-vision that parallels the communal quality of the ritual context in which giving glory often occurs. In this way, I bring sources from the eastern Mediterranean and Near East into conversation with western genealogies of “knowing thyself” and demonstrate how intrinsically linked our understanding of the senses is to the way we know and the way we imagine communion and empathy.

This study focuses on the literary subgenre of Mirrors for Princes. A number of twelfth-century works from three genres of Old French literature are examined in order to ascertain what forms any didacticism takes, and whether the texts can be read as Mirrors for Princes. The three genres studied are epic, romance and pseudo-historical chronicle. From epic, I discuss La Chanson de Roland, Le Voyage de Charlemagne, La Chançun de Willame and Le Couronnement de Louis. Chrétien de Troyes forms the study of Mirrors for Princes in romance, and for pseudo-historical chronicle I examine Wace’s Roman de Brut. The didacticism present in the studied texts assumes two forms. The first is direct didacticism, in which the narrator or a character portrays an instruction or moral lesson through “speech”. This gives extra emphasis to the message, whether addressed directly to the audience or to another character within the narrative. The second form is indirect didacticism, which is more common in these texts. It consists of exemplary characters, their actions, behaviour and reputations. The Mirrors for Princes aspects of these texts provide not only examples of successful kings, but also of excellent vassals and queens. The mirrors for the women involve virtuous characteristics, where they fulfil their wifely and noble duties. They are addressed to regents and queens consort more so than to queens regnant, who were uncommon figures in the twelfth century. As well as providing examples and lessons on what is optimal behaviour for the ruling class, there are characters who supply examples of behaviour that is to be avoided. With these ignoble characters, common methods of transmitting the didactic messages are through their lasting reputation, the consequences of their actions, or the nature of their deaths. The study concludes that the examined texts can be read as Mirrors for Princes, despite most of them not being originally conceived as belonging to this subgenre. Lessons for vassals, noblemen and noblewomen, queens and kings are present to varying extents throughout these works using both forms of didacticism outlined above.

Creative work and dissertation. Thesis (Ph.D.)--University of Melbourne, School of Art, Victorian College of the Arts, 2005. / Typescript. Includes bibliographical references (leaves 183-189).

Thesis (M.S.)--University of Michigan, 1978.