Adaptive Optics Overview

Adaptive Optics Overview Adaptive Optics Adaptive optics is a technological development used for optical system performance improvement. It works by reducing the effect of wavefront distortions. Light from a distant celestial object gets distorted as it passes through earths atmosphere, thus a telescope located on earths surface cannot form accurate images. It would take a telescope placed above Earths surface, such as the Hubble Space telescope, to acquire accurate images or a telescope able to measure the effect and attempt to correct it. Instruments using adaptive optics have been created for this exact purpose to eliminate the incoming distortion in light under the effect of our ever-moving atmosphere. Through adaptive optics, optical systems are able to adapt in order to compensate for the effects imposed by the medium in between an object and its image. This is considered the most revolutionary technical development in the field of Astronomy ever since 1609, when Galileo first used an astronomical telescope. A graphical example of this effect is presented below: Figure 1 When uniform waves of starlight enter Earths atmosphere they get distorted due to the variations in temperature in atmospheric cells. This causes the light to travel slightly faster in less dense and warm air, resulting in a non-uniform refraction. An adaptive optical system works by measuring the distortion of an incoming wave of light and correcting its deformation through deformation of a mirror. These optic systems function at high frequencies of around 1000 Hz, which is too fast to allow deformation of a primary mirror so a secondary mirror is used, along with other optical elements placed in the light path. The main use of adaptive optical systems is in astronomical telescopes and laser communication systems. It has other uses as well, such as microscopy and retinal imaging systems, but the primary progress has been developed in telescope technology. To better understand the way adaptive optics work, think of starlight as waves. When these waves reach Earths atmosphere, they are entirely flat, but the turbulence causes them to change shape. The telescope receiving a misshaped wave will return a blurry image. If a telescope with adaptive optics is used, the distorted waves would then reflect off of a deformable mirror which is equipped with hundreds of actuators on its back. These actuators detect the shape of the incoming wave and change the mirrors shape to match that of the wave. The result of this process is an almost entirely accurate image of a flat wave just as it was before entering Earths atmosphere. See figure 2. Figure 2 The system performs wave front sensing and wave front reconstruction, with input from adaptive mirrors. Wavefront Sensing (WFS) WFS provides a signal that is used to estimate the wave front shape. It involves an optical device that is phase- sensitive, along with a highly efficient, low noise detector for photons. The achromatic wave front means that the sensors usually operate within the visible spectrum where the CCD chips and photo diodes have a high quantum efficiency and are virtually noise free. There are mainly three types of WFS that operate in the broadband spectrum with varying sensitivity and dynamic range. They are the curvature WFS, the Shack-Hartmann WFS, and the Pyramid WFS. The Shack-Hartmann WFS is based on producing numerous spots corresponding to the local wavefront through the use of lenslets located across the aperture. The average wavefront slope over the subaperture is determined by observing the position of these spots. The Pyramid WFS is very similar to the Shack-Hartmann WFS when the pyramid is modulated. When the prism is hit on either side by an aberrated ray, it only appears in one pupil. Thus the slope is measured through the distribution of pupil images. The curvature WFS measures intensity distributions in two different planes, corresponding to the wavefronts curvature. The most advantageous part of the curvature WFS is the ease of use. In terms of sensitivity at high spatial frequencies, the curvature WFS performs better than the Shack-Hartmann but has low performance when it comes to low special frequency. Wavefront Reconstruction This helps to calculate a suitable correction vector (consisting of voltages sent to the DM from slopes measured at the WFS) to reconstruct the wavefront. In a closed loop, the WFS operates linearly, therfore the reconstruction of the wavefront can be described as: Dv = s + n Where n is the measurement noise usually assumed to be Gaussian and uncorrelated, D is matrix for the interaction between the wavefront sensing and the deformable mirror These vector matrix calculations are computing intensive, especially because they have to be carried out in microseconds regime. Linear-quadratic-Gaussian (LQG) or Kalman filter can be used to predict the systems state which would be an improvement of wavefront reconstruction and control. Using such a setup, telescope vibrations can be introduced in the state vector and corrected. The only drawback would be the computational complexity which may be overcome by keeping the use of the scheme to a minimum only applying it to certain modes. Deformable Mirrors (DM) The atmosphere distorts the incoming light. The induced optical path differences are corrected by the DM. The mirror surface can be deformed by the movement of many small actuators present beneath the optical surface. The resolution of this deformation depends on the number of actuators, their separation, operation speed, and response time. There are thousands of actuators present in the DM system for large ( There are three primary technologies used to produce adaptive optics deformable mirrors: deformable secondary mirrors (DSM), piezo deformable mirrors and micro-optical-electrical-mechanical systems (MOEMS ). DSM provides adaptive optics correction while keeping up and high transmission and low thermal emissivity. The position of the actuators is handled by an internal control loop. They are normally separated by a few cm and attached to an optical shell. Piezo DMs have a spacing of actuators of several millimeters. Their response time is over a hundred microseconds. Piezo DMs usually require to be controlled by 8 Davies Kasper, an adaptive optics system to provide stable wavefront quality because they do not have local position control. MOEMS use electro-static actuation. They are much smaller than other DMs due to their interactuator spacings of a few hundred microns. Their response time is almost instantaneous, however they require a very large number of actuators, which is currently a technological challenge. Throughout the development of the telescope which started 400 years ago with a small, manual device that later on evolved into a sophisticated, computerized instrument, two parameters have been vital: the diameter of the telescope and the angular resolution. Since the perfect telescope would have the resolution directly proportional to the inverse of the telescopes diameter, the ideal would be to convert incoming wavefronts into a perfectly spherical wavefront, only restricted by the diffraction limit. Adaptive optics were first envisioned by Horace W. Babcock in 1953,[6] but only entered common usage in 1990s, following computer technology development which made it a practical technique. This system was first applied to flood-illumination retinal imaging for the purpose of producing images of single cones in the human eye, in conjunction with scanning laser ophthalmoscopy to produce the first images of retinal microvasculature and associated blood flow and retinal pigment epithelium cells in addition to single cones. In 1995, Lawrence Livermore installed a laser guide star on the 3-meter Shane telescope at the University of Californias Lick Observatory, which later became the first major astronomical telescope consisting of full adaptive optics. There has been massive development in adaptive optics in the field of astronomy following these memorable points in history. However, given that in practice there are still too many errors distorting the wavefront, both due to atmosphere and telescope system, even adaptive optics have limitations. The primary challenges of adaptive optics are: the ability to create an optical system mechanically capable of correcting incoming waves of light and computers ability to keep up with the speed required by the atmosphere. For the first impediment, the telescopes at Mount Wilson Observatory, for example, use two mirrors working together a tip-tilt mirror which provides the correction of incoming light and a second deformable mirror which aims to shape after the distorted wave of light, making it reflect its actual shape as if outside Earths atmosphere. Both the distorted and undistorted images must be known by the system in order to determine the shape of the deformable mirror. There are several methods that can be used for determining the final shape of a point source at the Earths surface. The adaptive optics system at Mount Wilson uses a star near the telescopes target as the source of the distorted wavefront. That is, it looks at a star as seen through the telescope close to the object under study and determines how it has been distorted from its expected appearance. This technique is advantageous because no extra equipment is needed, the light from the source passes through the entire atmosphere and it is located in proximity to the object studied. The downside is that it requires the object being observed to be close to a relatively bright star. Because the isoplanatic patch for the atmosphere is so small, only a small part of the sky could be close enough to a bright star to be observed. There have been attempts to overcome this limitation by using lasers to excite sodium atoms producing an artificial star instead of a guide star. The technique involves projecting a laser beam into the sky close to the object of interest. As long as the lasers light is bright enough, there is no need for a guide stars light. The second challenge is caused by the ever-changing distortions. The deformable mirror must modify quickly to keep up with the incoming light. Since this part of the process must be handled through the use of computers, it requires that the systems be fast enough to analyse the incoming wave of light and transmit the appropriate commands to the mirror many times per second. Thus if the turbulence in the atmosphere is increased, the system will have to worker harder in order to achieve accurate results. Since the first astronomical adaptive optics systems were brought into common use in the early 1990s, a vast number of technical developments have been achieved, numerous ingenious techniques have been created, and it has now come to a point where it is inconceivable to even consider building a large telescope without adaptive optics. Sadly, many of the complex concepts today still exist only on paper or demonstrated on small scale only. Even though many of these innovations have arisen after 2000s, recent years have been mostly dedicated to developing the technology for practical, large scale use of these systems. It seems adaptive optics are fully developed on a theoretical level, but the practical progress is still lacking. It is expected that in the years to come the main areas to be explored and developed will be high-density deformable mirrors with thousands of actuators, high-power sodium lasers and powerful real-time computers with processors exceeding 109 to 1010 operations per second, along with, possibly, fast and low-noise near-IR detectors, since optical detectors with sub-electron read-noise and very high quantum efficiency are already close to perfection. Many recent astronomical discoveries are directly attributed to the new optical observation developments. With the help of Very Large Telescopes, the role of adaptive optics is very important. With this capability, their huge light-gathering along with the ability to resolve small details, has the potential to bring major progress in ground-based astronomy in the new decade. Further in the future, giant optical telescopes such as E-ELT, will rely on advanced adaptive optics systems for virtually all their observations.

A Mental Play About Everyday Language :: Dialogue Conversation Essays

A Mental Play About Everyday Language Characters: Alicia, an executive office worker Cindy, Alicia's secretary Mike, a local lawyer and acquaintance Carl, Alicia's husband Larry, one of Alicia's co-workers Mr. Alexander, a high standing government official Marnie, me, Alicia's friend and confidant Josh, Alicia's son PART I ALICIA: Cindy get me Mike on five please. CINDY: Alright. ALICIA: (on phone) Mike, it's Alicia Van Kleef. MIKE: (also on phone) Good morning Alicia. ALICIA: Say...I wanted to ask if you've heard anything new about the Dreyer case? Any ground-breaking material I should know or any new releases? MIKE: Dreyer...Martin Dreyer...yes. Another arraignment has been set for the fourteenth of next month with a few more pieces of evidence concerning the pre-event occurrences, and Judge Wilson is being replaced by Judge Lidboe. ALICIA: Any word yet about the plaintiff's tax evasion claim? MIKE: Other than the fact that they may have found more substantial material, I don't think their argument has changed. ALICIA: O.K. So the new hearing is on the fourteenth. MIKE: Yes. ALICIA: Great. Any particular reason for Judge Lidboe stepping in? MIKE: I heard that Wilson is taking another big case next week, and the court ruled that it was an open position for Lidboe then. ALICIA: Is that that upcoming negligence case from that Richland couple? MIKE: No, this is something out of down south. ALICIA: O.K. Thank you so much for the info, Mike. MIKE: No problem. ALICIA: I'll talk to you later. MIKE: O.K. ALICIA: Good bye. (She hangs up the phone.) CINDY: (entering office) Alicia, this is some mail that came in late yesterday, and a few reminders of things you wanted for today. ALICIA: Great. (paging through mail) Thanks Cindy. CINDY: You're welcome. Larry made some flavoured coffee from home this morning. It's pretty good. ALICIA: I'll have to give it a try before it's all gone. (mumbling to herself) I just hope Larry isn't hangin' around. (phone rings, CINDY waves and leaves the office) ALICIA: Hello, Alicia VanKleef speaking. CARL: Hey sexy. ALICIA: Hi Carl. CARL: How're you doin' so far? ALICIA: Just fine sweetie. I just got my coat off. CARL: Did you take anything else off? ALICIA: No, dear. Strip shows aren't allowed in the office. You know that. CARL: (laughing) Sorry. ALICIA: Did Josh find his other shoe this morning? CARL: Yeah, under his bed, like you said. ALICIA: He gets so frustrated over little things like that. CARL: He calmed down after he found it. ALICIA: Good. It was his jacket last week. CARL: Yeah.

Organizational Staffing Plan: Part 2

The purpose of this paper is to provide additional insight into the staffing process to be implemented by the coffee shop. This paper will present several key points in order to procure final loan approval. These points include the formulation of a recruitment plan and strategy, which will be used by the coffee shop initially and throughout the next three years. The targeted communication message and delivery medium will be presented for the purpose of attracting applicants. The selection process to be used will be identified as well as the advantages and disadvantages of this process.The types of initial and substantive assessment methods that can be used to select external candidates and how these assessments align with the staffing strategy will be discussed. And finally, the predictors which will be used to assess the KSAOs will be identified. Recruiting Plan and Implementation Strategy The coffee shop is a smaller business and does not have the staff or budget to run its own rec ruitment functions effectively. The recruitment strategy that will be used to staff the coffee shop initially and throughout the next three years will be the use of an employment website.This open recruitment plan will allow the coffee shop to attract a very diverse set of applicants. The benefit of the employment website is that they will be able to provide the advertising, video advertising, pre-employment screenings, and applicant tracking (Heneman, Judge, & Kammeyer-Mueller, 2012, p. 222). Once the initial recruitment has been accomplished, it will be in the best interest of the coffee shop to change the strategy slightly and move towards a more targeted recruitment plan. The coffee shop will be better equipped to handle placing their own advertisements, utilizing social media, and networking from within the staff.This strategy will benefit the coffee shop because they will be able to seek specific individuals with certain, knowledge, skills, ability, and other characteristics. Creating a Communication Message Once the coffee shop moves into their more targeted recruitment plan, they will need to develop a communication message. The communication message is one of the most important aspects to attracting applicants to the available positions. It will be very important to resist the urge to make the message all inclusive. To increase accuracy, the coffee shop will need to aim for one target audience per message.This will mean that there will be multiple messages, but only one message for each position description. It will also be very important that the targeted message reaches the target audience. Therefore, it is imperative that the message convey the benefits of the position to the proper audience (Massachusetts Service Alliance [MA Service Alliance], 2013). The coffee shop is considering using the following targeted communication message for advertising the coffee server positions. Of course this message is being targeted to the nearby college students. Are you looking for a way to make some extra money? Are you looking for more than just a job? Join us in our warm, friendly coffee shop. This will be different from other jobs. You will enjoy working in our fast paced environment. You’ll have the opportunity to make great connections with our customers while providing them with quality beverages and food products. Come join our team while building relationships that will last a lifetime. We offer flexible schedules, great benefits and an environment that is truly welcoming. Selecting an Effective Communication MediumBecause the coffee shop’s initial strategy is to use an employment website, the communication medium for the recruitment effort would be the internet. Utilizing the internet will enable the shop to recruit from a vast and diverse talent pool of applicants. An employment website is second only to referral as a source of new hires (Heneman, Judge, & Kammeyer-Mueller, 2012, p. 222). Once the initial recruitmen t is complete, the coffee shop will move to a different communication medium. The coffee shop will be able to utilize advertisement options such as classified ads, radio and television ads, and word of mouth.Because word of mouth is one of the most powerful methods of communicating job opportunities, the coffee shop is anticipating that the current employees will be able to ‘sell’ the coffee shop. In order to minimize advertising costs, it will benefit the coffee shop to utilize social media. Facebook, Twitter, and many other social media sites are a great way to reach out to the community. By maintaining pages on these social media sites, the coffee shop not only will be able to advertise for open positions, but they will also be able to advertise the company and drawin new customers. Selection Process Putting the right person into the right position is the goal of an effective selection process. By selecting the right applicant for each of the positions, the coffee sh op will face less absenteeism and employee turnover problems. In addition, the coffee shop will also save time and money (â€Å"Selection Process,† n. d. , Para. 1. ). To begin this process it will be necessary to determine the Knowledge, Skills, Abilities, and Other characteristics (KSAOs). And then determine which KSAOs are necessary to assess the applicants.Once identified, a method to assess the KSAOs will need to be determined. The advantages of selecting the employees this way is that the coffee shop will eliminate unqualified applicants early in the process. However, the disadvantage is that it may significantly lessen the pool of applicants. This may require additional time and cost in advertising again for the positions. Selection Assessment Methods By utilizing an employment website, the coffee shop will be presented with applicants that have been prescreened.However, once the coffee shop is established and discontinues the use of an outside agency, it will need to prescreen them to determine which applicants are likely to be high performers if hired. The initial assessment begins with a review of the resume. This review will be necessary to determine if the applicant has listed any skill or experience that meets the qualification requirements. In the case of the store manager, the coffee shop will be looking for retail experience, supervisory experience, and experience analyzing financial reports.Although, a college degree in business or a closely related field may substitute for a portion of the required experience. In addition, the manager position requires a high school diploma. For the server, the experience should be reflected by customer service and cash handling experiences. Once the applicant pool has been reduced to eligible candidates, a structured interview will be conducted. This substantive assessment will be conducted by the owner of the coffee shop. The structured interview will allow for three to five questions.These same ques tions will be asked of each candidate and will be developed based upon the KSAOs relevant to the position. The questions should reflect the candidate’s behavioral response, either by past behavior or by potential future situations. Benchmark responses and rating scales will be developed in conjunction with the questions to allow for the most desirable evaluation. If it is determined that some of the questions are more important than others, those questions will be weighted. Predictors to Assess KSAOs As seen in the first paper presented, the KSAOs have already been presented.The coffee shop will utilize the necessary KSAOs to further assess the applicant’s knowledge and experience. For the position of store manager, some of the KSAOs that will be necessary are the ability to manage effectively in a fast-paced environment, ability to manage store operations independently, ability to manage multiple situations simultaneously, interpersonal skills, knowledge of customer s ervice techniques, organization and planning skills, team-building skills, ability to plan and prioritize workload, and ability to handle confidential and sensitive information.For the position of coffee server, the KSAOs used in the assessments would be the ability to learn quickly, strong interpersonal skills, the ability to work as part of a team, and the ability to build relationships. In order to predict successful job performance both the resume and the results of the structured interview will be reviewed. The knowledge listed on an applicant’s resume should become highly relevant during the structured interview. The structured interview will allow the candidate to reveal verbal skills, which are necessary to successfully communicate with both fellow workers and customers.The applicants resume will reflect required abilities while the interview will appropriately assess them. Other individual characteristics may be predicted through during the interview. The candidateâ €™s personality, which will not show in a resume, will be revealed at the structured interview. Conclusion For the coffee shop to be successful, it will need to have a recruitment plan as well as a strong strategic plan for the first three years of the business.

Introduction to Psychology Essay examples - 1348 Words

Introduction to Psychology The concern about life is a main human characteristic. No matter if his concern is concentrated in himself or in persons or things that surround him and constitute his environment, everybody wants to know why people, himself included, behave the way they behave. Everybody, also, wants to improve his behavior, so as to live in harmony with himself and the society. The Greek word Psychology, is a word consisted of the words #968;#965;#967;#942;-soul and #955;#972;#947;#959;#962;-utterance, talk. So, generally, psychology is the science that examines the soul. But , since the psychologists work on the problems of the personal, family, school, professional and social life, we could say, more†¦show more content†¦The heartbeats, the movements of our head are behavior. The way we eat, the way we drink, the way we walk, we talk, are behavior. The construction of a bridge, the composition of a song are behavior. The fantasies of a child, the dreams of a adolescent, the illusions of an alcoholic are behavior. Although we are all familiar with human behavior, a little do we understand or we can explain about it. Since our infancy we learn about behavior through the experiences and the knowledge that we get by observing other people or having relations with them. Living in society leads us to watch and try to explain the way people behave. But that is not always easy. Sometimes we cannot understand even ourselves. Psychology comes to give answers to all this uncertainty. Therefore, according to modern psychology, the term behavior means all the conscious, unconscious, verbal, mental and kinetic expressions of ourselves. Psychology uses statistic researches so as to distinguish the normal behavior from the abnormal one. 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