Star Testing Astronomical Telescopes（关于光轴矫正）

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Many observers harbor misgivings about their telescope. The manufacturer may have guaranteed accuracy to “one-quarter wavelength” or as “diffraction-limited” but most telescope users have, at best, only a hazy idea of how to personally verifying such claims. Sure, there are ways to check the accuracy of individual components but for many they are hard to understand or require costly reference optics and other test equipment. Besides, telescope users are interested in the performance of the entire optical train, not just the main optical element.

What is really needed is a test that can be used at the observing site, so that all the problems that impact on a telescope's performance can be diagnosed. Isn't there a simpler and more complete way than the complicated shop tests? Yes, the star test is such a method. It uses the entire working telescope. It is not a poor substitute or a work-around that uses bits and pieces of the optical system. It is the oldest and most sensitive of the optical tests—an inspection of the diffraction image itself.

Star-test results apply to the complete imaging performance of the telescope. The star test is lightning-fast and requires only a good high-power eyepiece. It tests the telescope for precisely what it was meant to do. Bad or poorly-aligned instruments fail the star test unambiguously. The star test often allows you to correct the optical difficulty immediately in the field, when you might be frantic to have your telescope perform well to observe a once in a lifetime event.

While the star test has been around for centuries learning it has often been hampered by messy mathematics and its visual nature. Most people who use it have learned it at the elbow of a patient Master. In this book, Dick Suiter becomes your Master. He carefully shields you from difficult diffraction theory and uses advanced computer generated graphics to show you the appearance of each aberration. Again and again, you will look at Dick's graphics and say “I've seen that before. So that's what it was!” The star test is a powerful but inexpensive way of obtaining better resolution and contrast. With this book most observers will find that they don't need a new telescope because they now can test, diagnose and fix the one they have. Using Star Testing Astronomical Telescopes as a guide, your telescope will perform to the best of it's abilities and perhaps it will show images better than you would have believed possible.

From The Reviewers

Tonight’s the night. That $800 telescope you’ve been waiting for has finally arrived. After excitedly setting it up, you center Jupiter in the eyepiece. Excitement builds. You focus and focus again, switch eyepieces, focus again. The view is horrendous! What’s causing it? Is it just unstable atmospheric conditions or are the telescope’s optics out of alignment? Is it heat rising off the asphalt parking lot you’re observing on or is the telescope too warm? Or, horror of horrors—could it be that your new mirror is not up to specifications? And what kind of flaw is it? Rough surface? Spherical aberration? Astigmatism?

Far too many of us have experienced this disturbing scenario. But now, thanks to Star Testing, you can answer these questions easily and probably have the telescope operating in no time. And if there is an optical problem, you will be able to communicate it clearly to the dealer and get prompt action.

Chapter One and Two explain basic optics in a fashion that any motivated beginner can follow. Computer-generated illustrations of defocused star images are so realistic that you can learn a great deal by just looking at the pictures . . . Star Testing is bound to have a big impact on our hobby. Harold Suiter wants to help buyers assess optical quality so that it plays a larger role in purchasing decisions. This, he feels, will give manufacturers added incentive to produce superior products. In my opinion Suiter will succeed—if enough of us buy this book and read it. Its cost is a small price to pay for becoming an informed consumer.

                                                                                             Astronomy magazine

"I’m going to tell you a little-known fact," begins Harold Richard Suiter in his new book . . . "Telescopes are easy to test." It’s true. The hard part for most amateurs has been finding out exactly how to do it . . . Now, at last, Suiter has analyzed the star test in book-length thoroughness. He presents a bounty of information and instruction in a clear, practical manner never before available . . . The book displays with perfect clarity all the star test comparison images you’ll ever need, illustrating all kinds of telescope aberrations in their pure forms . . . Those are just highlights of this long overdue book. It quantifies almost all the effects it discusses, presents modulation-transfer functions indicating how they affect different types of observing, delves into diffraction theory, and yet is full of advice and experience from real-world amateurdom.

Sky & Telescope magazine

It is very rare to find a book that has such an immediate appeal to the telescope maker, observational astronomer, and theoretical physicist….A first casual inspection of the book indicates that it should reside on the applied optics book shelf of a Physics Department library. Nothing could be further from the truth. Suiter, who is an experimental physicist, has been very successful in using everyday analogies to explain the fundamentals of diffraction optics. There is a great deal of good practical information for those readers prepared to persevere. For those with a more than casual approach to their telescopes, this book will become in the widest sense, a benchmark in astronomical telescope testing literature. Most importantly, it will give some weight to increasing the quality assurance standards of commercial telescopes, from the viewpoint of a better informed user.

Southern Stars

Some Examples

Testing your optics to confirm quality is obvious. What is less straightforward is the way of testing. Telescope makers can use a variety of techniques, but ordinary telescope users find that learning a workshop method is difficult. They have only one mirror that doesn't change, so it is easier to test it on the sky. The star test is a good way of evaluating instruments for one-time users.

You must be careful to test the instrument when it has cooled off and is under fairly tranquil skies, as the following spherical aberration with strong turbulence figure shows.

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The following aberration types figure shows some common difficulties with telescope optics.

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当然前提是你必须先找到调光轴的螺丝

夜猫子

郁闷啊，看不懂英文！(:(

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Originally posted by 夜猫子 at 2006-1-7 07:50 PM:
郁闷啊，看不懂英文！(:(

其实看图就差不多了

跨越地平线

Many observers harbor misgivings about their telescope. The manufacturer may have guaranteed accuracy to “one-quarter wavelength” or as “diffraction-limited” but most telescope users have, at best, only a hazy idea of how to personally verifying such claims. Sure, there are ways to check the accuracy of individual components but for many they are hard to understand or require costly reference optics and other test equipment. Besides, telescope users are interested in the performance of the entire optical train, not just the main optical element.
许多天文爱好者关心他们的望远镜。 制造厂已保证准确性达到“一又四分之一波长”作为“有限的衍射”但是大多数天文望远镜用户想拥有亲自制作一种仅仅用模糊镜的方式来验证的方法。当然，有一种方式可以检验组成部分的准确性；但是，对于他们（天文爱好者）是有许多困难的，比如需要昂贵的光学设备和其它测试设备等。  此外，望远镜的用户对整个望远镜的光学性能非常感兴趣，仅仅主要取决于光学的因素。

What is really needed is a test that can be used at the observing site, so that all the problems that impact on a telescope's performance can be diagnosed. Isn't there a simpler and more complete way than the complicated shop tests? Yes, the star test is such a method. It uses the entire working telescope. It is not a poor substitute or a work-around that uses bits and pieces of the optical system. It is the oldest and most sensitive of the optical tests—an inspection of the diffraction image itself.
十分需要一个地点用来测试望远镜，这样才能了解这个望远镜的性能。 有没有更简单更完全的测试方法？ 有的，光轴矫正是其中一种方法。 它需要使用一整个能正常工作的望远镜。它在光轴矫正—观察一个衍射图象本身中是最陈旧和最敏感。

Star-test results apply to the complete imaging performance of the telescope. The star test is lightning-fast and requires only a good high-power eyepiece. It tests the telescope for precisely what it was meant to do. Bad or poorly-aligned instruments fail the star test unambiguously. The star test often allows you to correct the optical difficulty immediately in the field, when you might be frantic to have your telescope perform well to observe a once in a lifetime event.
光轴矫正后的计算结果可以说明这个望远镜的性能。光轴矫正是快速的并且要求需要高倍数的目镜。矫正望远镜时必须做得十分精确。坏掉的、受损的仪器进行光轴矫正是不准确的。 当你安排你的望远镜执行光轴矫时时，也许让你终身难忘。

While the star test has been around for centuries learning it has often been hampered by messy mathematics and its visual nature. Most people who use it have learned it at the elbow of a patient Master. In this book, Dick Suiter becomes your Master. He carefully shields you from difficult diffraction theory and uses advanced computer generated graphics to show you the appearance of each aberration. Again and again, you will look at Dick's graphics and say “I've seen that before. So that's what it was!” The star test is a powerful but inexpensive way of obtaining better resolution and contrast. With this book most observers will find that they don't need a new telescope because they now can test, diagnose and fix the one they have. Using Star Testing Astronomical Telescopes as a guide, your telescope will perform to the best of it's abilities and perhaps it will show images better than you would have believed possible.
光轴矫正是大约有几个世纪前就诞生了，它经常被杂乱的数学和视觉性质搅在一起。 使用它的大多数人是在一位耐心的硕士写的书那儿获得的。 在这书中，迪克成为了你的硕士。 他从复杂的衍射理论里，用制图法细心地描绘每一幅失常的画面。 一而再地，你将看到法迪克用制图法描绘的画面时，一定会说“我以前见过那个！就是它！” 光轴矫正是十分权威的。但是，看完这本书后大多数天文爱好者发现他们不需要一个新的望远镜，因为他们现在就能测试，诊断完后就可以修理他们的坏掉的望远镜。 使用光轴矫正已经成为使用天文望远镜时必备的一本指南，这样你就能了解你的望远镜是否充分发挥出它的性能。

From The Reviewers
评论

Tonight’s the night. That telescope you’ve been waiting for has finally arrived. After excitedly setting it up, you center Jupiter in the eyepiece. Excitement builds. You focus and focus again, switch eyepieces, focus again. The view is horrendous! What’s causing it? Is it just unstable atmospheric conditions or are the telescope’s optics out of alignment? Is it heat rising off the asphalt parking lot you’re observing on or is the telescope too warm? Or, horror of horrors—could it be that your new mirror is not up to specifications? And what kind of flaw is it? Rough surface? Spherical aberration? Astigmatism?
今天晚上，你兴奋地把它装好之后，你把在目镜中聚焦后的木星定位在中间后，然后你再一次聚焦，反复聚焦，再聚焦一次。 看到的将是是可怕的！是什么原因？是不稳定的大气层影响望远镜吗？ 是温度造成的吗？？是反射镜起伏不平的表面？  散光？

Far too many of us have experienced this disturbing scenario. But now, thanks to Star Testing, you can answer these questions easily and probably have the telescope operating in no time. And if there is an optical problem, you will be able to communicate it clearly to the dealer and get prompt action.
许多人经历过这种烦扰的事情。 但是现在，由于光轴矫正，你能容易地回答操作望远镜时遇到的问题。 同时，如果有一个光学的问题，你无法解决的，那你就要跟生产厂家询问了.

(未完代续……)

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好支持

夜猫子

谢谢跨越地平线的翻译!

我爱祖祖

楼主,我满世界找这本书,请问国内从哪里可以买到呢?