Laser Alignment Theory Essay Example for Free

Laser Alignment Theory Essay Modern optical metrology uses precise lines and planes in space from which measurements are made. Because this method creates these features using light it has become known as optical tooling. The 35 year old historical development and current technology of laser instrumentation as used in optical tooling is discussed in detail. This includes the how the measurements are made, applications, and the technology of alignment lasers and position sensing targets developed for sensing position within a laser beam or plane. The various geometries used to make alignment measurements are discussed in detail. Applications are discussed and the challenges each poses are discussed. The challenge of long range alignment and the effect of the turbulent atmosphere on the measurement process is discussed along with methods of handling the associated errors them. WHAT IS OPTICAL TOOLING? Optical tooling is a means establishing and utilizing a line of sight (LOS) to obtain precise reference lines and reference planes from which accurate measurements are made with position sensitive targets. 1] Formerly the measurements were done by a person interpreting a scale or optical micrometer by looking through an alignment telescope; today the lines and planes are created by a laser; the measurements are digital and require no interpretation. Optical tooling uses the principle that light travels in straight lines to produce precise measurements that cannot be reached by manual or mechanical methods. Level lines can be esta blished over great distances so accurately that every point is exactly perpendicular to the force of gravity. Plumb lines can be set to a given level. Right angles can be produced quickly and precisely with auxiliary components. In the assembly, maintenance and calibration of industrial equipment or in the alignment of precision systems, one or as many as four basic questions always must be answered: is it straight, is it flat, is it plumb or is it square? A number of techniques have been developed to make these measurements; however, many of them result in inaccuracies so great that proper operation of the equipment involved will be compromised or seriously endangered. The science of optical metrology and alignment makes it possible to achieve the highest degree of accuracy in answering these four important questions. It is no longer necessary to interpret readings or to make constant adjustments and calculations. In laser alignment applications, direct, precision measurements are made rapidly and consistently. Straightness In aligning several points, a tight wire is often used as a reference line. This technique has numerous drawbacks and introduces inaccuracy. First of all, wire has weight, which causes it to sag; over long distances this sag can become considerable. In addition, wire vibrates, can bend or kink, and when stretched in the area to be measured, equipment cannot be moved around for fear of disturbing the wire reference line. Even a gentle breeze can cause the wire to move sideways a considerable amount; the aerodynamic drag on a thin wire is huge. In laser alignment, the LOS of is established by a laser beam instead of a tight wire. The invisible LOS reference has no weight, cannot sag, kink, or be disturbed, nor is it a safety hazard. It constitutes a precise, unvarying reference, determining straightness to within thousandths of an inch. Flatness In order to determine flatness a shop level and a straightedge was employed in the past. However, over large horizontal areas, the shop level must be moved from part to part. Consequently, one can only tell the degree of flatness of each individual surface upon which the level is place. Whether all objects in a large area are flat is still in doubt. Flatness over a considerable area must be assured in the erection of large machinery, surface tables and large machine tools. Conventional bubble levels simply do not offer the degree of precision required. Laser levels, a termed that has fallen into generic use, offer a way to produce a level datum over a wide area. Laser technology has overcome the many disadvantages of bubble levels and assures levelness to within a few thousandths of an inch over hundreds of feet. This high degree of levelness is accomplished by horizontally sweeping the laser beam manually or via a motor driven rotary stage. This revolving line of laser ligh t becomes a horizontal plane of sight, giving a precise horizontal reference datum, sometimes called a waterline. Squareness Perfect squareness implies that one plane forms a 90Â ° angle with another intersecting plane. When a steel square is used to test for this condition, the results can be very misleading. Such measurements rely upon the trueness of the steel square, which can vary from square to square with time. In addition, steel squares have a definite limit in their physical dimensions and consequently the testing of very large surface becomes inaccurate, slow and cumbersome. Laser alignment overcomes all these disadvantages and offers a quick and precise method for determining squareness. One method is to use a transparent penta prism in conjunction with a simple alignment laser. This optical element will split the beam from the laser into two parts; one beam passes through the prism undeviated, the other beam is reflected at a perfect 90 degree angle. This will be described in more detail later. Other systems use three independently mounted lasers that are orthogonal to each other. Plumb Classically, a plumb bob is used to establish a single vertical reference line. Of course, as vertical distances increase, the plumb bob becomes cumbersome and inaccurate. It takes a long time for the plumb bob to settle. Also, it can easily be swayed by vibration, air currents, and other disturbances which are bound to be encountered. In the laser alignment method there are several ways to produce a plumb reference; it can be a plane or a line. To form a plumb line, an alignment laser with autocollimating capability is used with a pool of almost any liquid. Autocollimation senses the angle of an external mirror by reflecting its beam back into the laser head. A position sensor, beamsplitter and lens measure the angle of the reflected beam. When the laser is adjusted such that the internal sensor reads 0 in both axes, then the laser is producing a plumb line. For example, if a heavy machine tool is being surveyed, the two reference points which determine the LOS should be located off of the machine. If for any reason the machine were to move or deflect all measurements would be in error. The two reference points should be located close enough to be convenient to use and/or out of the way of other people working in the area. Transits and alignment telescopes first made these types of measurements. But the problem with transits and telescopes is that they require a person to interpret a scale placed on the object of interest; and usually a second person is holding the scale against the object. It is a two person job that takes time and much training to accomplish successfully. It is also subject to errors. This type of alignment measurement, commonly called straightness, is the most basic of all alignment applications. The figure below shows an alignment laser source on the left whose collimated beam is striking a position sensor target on the right. The target can freely slide and make measurements of straightness of the structure to which it is attached. [pic] Another common requirement is to establish another LOS perpendicular or parallel to the original LOS. To establish a perpendicular a special prism is used: a penta prism. A penta prism has the property that rotation around its axis does not deviate the reflected beam at all; it does not have to be critically mounted. Penta prisms are often called optical squares, an appropriate term. To establish a parallel LOS to an existing LOS typically involves tooling bars if the distance is relatively short, say a meter or less. These bars are made of steel and hold electronic targets at a precise distance from a center. Using two of them with the original LOS establishes a parallel LOS. If the distance between the two LOS is large, then it can be done using the penta prism twice; the first time to turn the beam 90 degrees, followed by a certain distance, and concluded by turning the beam back 90 degrees. Care must be taken that two LOS are truly parallel; usually using a level reference datum makes the task much easier. The next alignment application involves measuring the alignment error between two different LOS datums; the typical application is to determine the lateral offset and angular error between two shafts. The shafts essentially define the two LOSs. The measurement consists of setting up the source on one shaft and parallel to it. The targets are placed on the second shaft and surveyed. Then the shafts are rotated 180 degrees and surveyed again; the difference is twice the shaft offset. If the target is placed at two axial locations and measured for offset, the difference in the offsets divided by twice the axial separation is the angular error in radians. The figure below shows a typical method to measure shaft alignment errors using a laser and target. [pic] A more sophisticated alignment application is to sweep a laser beam quickly to generate a plane of light. The advantage of this is that many targets can be aligned using one laser source. In simple straightness applications the target location is restricted to the active area of the position sensor. In swept plane alignment, the targets are using sensitive in only one dimension. A typical application to establish a level plane is to put three or more targets at the same (desired) waterline location and adjust the structure the targets are on until all targets read the same. The targets for swept plane alignment can be static, meaning they require the laser beam to be directed in to them constantly. Usually the laser beam is swept by hand by rotating a knob on the laser source. If the laser plane is moving at high speed, say once a second or faster, then the targets must capture and hold the position of the laser beam as the beam sweeps by. The problem becomes harder to accomplish at longer distance because the beam is on the detector for such a short periods of time. The figure below shows a horizontally swept level laser beam scanning by several targets placed on a machine bed.

News Summary and Reaction :: Summary and Response

News Summary and Reaction ASTRONOMY â€Å"A New Black Hole† â€Å"Scientific American Evidence that the heavens house a previously unknown type of black hole was reported by scientists yesterday. Data from NASA’s Chandra X-Ray Observatory revealed a hole was some 600 light-years from the center of the starburst galaxy M82. The brightness of the x-ray source indicates that this moon-size hole has the mass of at least 500 suns, making it intermediate between stellar black holes and the supermassive black holes found at the centers of galaxies. â€Å"This opens a whole new field of research,† said Martin Ward, a lead author on one of three papers to be published on the subject. â€Å"No one was sure that such black holes existed, especially outside the centers of galaxies.† Earlier data from the Roentgen Satellite and the Advanced Satellite for Cosmology and Astrophysics had suggested that M82 might contain a large black hole outside its nucleus, but the Chandra results seal the deal. The new object might have resulted from the collapse of a â€Å"hyperstar† or the growth of a smaller black hole through mergers with others nearby. --Kate Wong Summary   Ã‚  Ã‚  Ã‚  Ã‚  A new unknown type of black hole was discovered on September 12, 2000. It was found to be 600 light-years of the Starburst Galaxy M82. An x-ray source indicates that the moon-size black hole has the mass of at least 500 suns, â€Å"making it intermediate between stellar black holes and the supermassive black holes found at the center of galaxies† (Scientific America, 1). Scientists were shocked at this discovery, for they didn’t know that these types of black holes existed. Scientists believe this black hole may have been due to a collapsed â€Å"hyperstar† or the growth of a smaller black hole through mergers with others nearby. Reaction   Ã‚  Ã‚  Ã‚  Ã‚  I find this so very fascinating because I can not even fathom how space and galaxies exist. With newer and faster technology, come new discoveries, and I think it’s great that we have the chance to explore a whole new frontier unlike the one we live on. I am in awe of what is possible today through the means of such a technologically advanced society. To know that people are able to leave our earth completely, in search of bigger and better things, utterly blows my mind. The Future   Ã‚  Ã‚  Ã‚  Ã‚  Through our discoveries we uncover more and are able to advance due to the information that we accumulate. Our work and discoveries lead to new inventions, which in turn change our lifestyle.

Of Mice and Men Essay

The book Of Mice and Men focuses on the friendship of two migrant workers in California at a time when most of the work was done by people and not by machines. George was a small man who acted worldly and wise. Lennie was a huge man that had the mind of a child. Together George and Lennie would bounce from job to job with no money in their pockets and only the dream of someday owning a place of their own to keep them going. The two men were not able to stay in one place too long because Lennie would get into trouble and George would have to get the two of them out of the bad situation and find a new place to work until the next bad thing would happen. Why would George continue to complicate his life by dragging Lennie around? Why wouldn’t George just set off on his own and make his life a whole lot easier? It was obvious when I read through the book that Lennie could not have survived in the world without somebody like George watching out for him. As the story unfolded I had to ask myself, â€Å"Did George need Lennie as much as Lennie needed George? † Two men traveling together the way George and Lennie did was not very common during this time. Slim said to George on page 39, â€Å"Hardly none of the guys ever travel together. I hardly never seen two guys travel together. You know how hands are, they just come in and get their bunk and work a month, and then they quit and go out alone. Never seem to give a damn about nobody. † Why did George and Lennie travel together then? It is easy to answer that question when looking at it from Lennies point of view. Lennie needed somebody to protect him. Lennie had the mind of a small child and would not have been able to find work, feed himself or stay out of trouble if not for somebody like George. The reason why George traveled with Lennie on the other hand is a little bit more complicated. One reason may have been George made a promise to the person who took care of Lennie before George that he would. Does this mean that George is such a stand up person that he would not go back on his word? Maybe but I don’t think it is the main reason he put up with Lennie and all the trouble that came with him. Another reason George may have kept Lennie around was that Lennie was such a great worker that it made George’s life much easier always working alongside of him. A third reason why George may have continued to travel with Lennie was that George liked the fact that he was in charge of Lennie, similar to how a father was in charge of what his son does. George had so little in his life that maybe having Lennie around to tell what to do all the time made him feel needed or important. Jus’ tell Lennie what to do an’ he’ll do it if it don’t take no figuring. He can’t think of nothing to do himself, but he sure can take orders† George tells Slim on page 39. A fourth reason George kept Lennie around is maybe Lennie made George feel smart. George seemed like the kind of person that liked to feel he was smart. The last reason I can think of and probably the biggest reason was that George needed the company. I don’t think that George could even imagine living how he lived and not having anybody to share anything with, including his ideas and his dreams. Ultimately, I think all of these reasons played some role in why George kept Lenny around but fear of being alone was probably the biggest reason. Something good is gained by both parties in every successful relationship and the relationship that George and Lenny have was no exception. Lenny of course received protection and a person to take care of him. Those are two things he could not have survived without. I think what George gained most from the relationship was becoming a better person. On page 41, George says to Slim, â€Å"I ain’t got no people. I seen guys that go around on the ranches alone. That ain’t no good. They get wantin’ to fight all the time. † George meant he didn’t have any family at all. George was afraid if he lost Lennie, he would never have somebody close to him again, he would be all alone and turn mean. That is what George got most out of the relationship, the friendship he believed made him a better person. I think George proved just how much he cared about Lennie at the end of the story when he shot Lennie in the back of the head by the creek. George made the ultimate sacrifice in killing Lennie and putting himself in the position that he feared the most which is being along. George knew if anybody else found Lennie, especially Curley, they would have made Lennie suffer to pay for killing Curley’s wife. It was interesting what happened earlier with Old Candy and his dog being put to sleep. Old Candy seemed just as upset about not shooting the dog himself as losing the dog. â€Å"I should have done it myself†, Old Candy said near the end of the book. Maybe George learned from that. George believed the right thing was for somebody who cared about Lennie to end his life no matter how much it hurt. Of Mice and Men is a book about relationships with the relationship between two very different people, George and Lennie, at the forefront. Early on it seemed very obvious that Lennie got the most benefit from their friendship. As the story unfolds, it’s not so obvious. In the end, I believe that George benefitted as much or even more than Lennie from their strange friendship. George believed that Lennie made him a better person.

Should Animals Use For The Experiment - 1229 Words

Ngan Phan Jessica Oxendine 1301-83450 05/09/2017 Should Animals Use for the Experiment? Today s medical advances are updated and developed on the news. However, the information they give to the customer is the final research. As a taboo, previous trials conducted on animals will not be mention on the package. The sacrifice is the life of animals, finances, even including the adverse effects on patients when the results on humans are entirely different from those predictable on animal models. I do not agree with animal experiment because it is against humanity. To create the new quality of makeup products or pharmaceuticals, we are using millions of animals such as mice, rabbits, monkeys, dogs, etc. They have to trade their lives in†¦show more content†¦Along with bringing down the country’s economy, those tests will lose trust incorporation between companies. U.S Food and Drug Administration since 1950 states â€Å"Only 6% of 4,300 international companies involved in drug development have registered a new drug† (Arguments against animal testing.) By looking at the above information, we can see how bad investment sources have been decreasing, and this struggle won’t be improved until the human has a serious attitude about their ethics to animals. Animals Testing is not only about taking animals life away by people, but they are also pushing themselves into another obstacle. They have the thought that by using animals for new treatments can give them advantages, but they forget one thing that animals body structures are entirely different from humans. That means, the new drugs may have positive effects on animals, but who knows whether they contain some reactive ingredients can cause harms for people or not. For example, from Dr. Richard Klausner, former director of the US National Cancer Institute made a statement about the failure using the drugs on humans. He said that medicine cured for cancer work on mice butShow MoreRelatedShould We Use Animals For Experiments?1335 Words   |  6 Pagesyears, people think of using animals for an experiment is an awful thing to do. It may seem to be disturbed to some people, but it helped medical researchers to figure out and create new medicines to cure the illnesses that have not a cure yet. How could animals help us with the experiment? If we cannot use animals, then what or who could replace them? Should we use humans for experiments? Until now, people still argue whether we should stop using animals for experiments or not. What people must understandRead MoreShould Animals Use Animals Be Used? An Experiment?1946 Words   |  8 Pagesstart animal testing. 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Do animals make appropriate research subjects and is it absolutely necessary to use animals to test the safety of products? Animal testing can be referred to in a number of ways including animal research and animal experimentation, all of which involve experiments performed on animals to test the safety and effectiveness of thingsRead MoreAnimal Rights : Animal Or Its Organs And Tissues Are Used1335 Words   |  6 Pagesexperimental procedures, either a whole animal or its organs and tissues are used. For this purpose animals are euthanized (killed) by established methods. Many times, the animals surviving the clinical testing are euthanized at the end of an experiment to avoid the later pain and distress (Rusche, 2003). In some cases (for example in LD 50 analysis) animals die as a result of the experiment. 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