德国进口BAADER观测摄影用太阳滤光膜（10cmX10cm）

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一种新型的滤光方式___巴德太阳观察保护膜Astrosolar TM—
   在观察太阳活动和日食、以及太阳摄影时,传统的方法是使用中性灰滤光镜..但现在有了更加便宜、更加有效和更高性能的新型的滤光方式,这就是来自德国的发明专利___巴德太阳观察保护膜AstroSolar TM,该专利已在欧洲19国注册,注册号99101807.8,现正在美国参加"世纪天文产品"评选活动.
一、  背景及简介
    *光学质量   该极高精度的薄膜在干涉测量时一致产生出94-96%的斯太尔率(STREHL RATIO)  由此在光学上的特性形同于一些世界著名专业公司生产的氟化钙三片式物镜(就干涉测量结果而言).由于很难区分太阳观察保护膜AstroSolarTM和一些世界著名专业公司生产的1/20λ 精密光学窗口的光学质量, 1/20λ精密光学窗口可能会突然间变得一文不值、简直无法售出.该保护膜与所知的任一好的同功能产品、特别包括所有的玻璃物镜滤光镜 ,均显示出显著的更加锐利的对比度.
    更重要的是,保护膜AstroSolar TM 使太阳显示出其真实色彩: 中性白色. 而其它膜和玻璃滤色镜产生出有兰色或红色光晕的太阳像, 割裂了部分光谱:特别是当观察橙色太阳时,极难于观察到主要分布在光谱兰色端的太阳耀斑.
    *眼安全   太阳观察保护膜AstroSolar TM 基本上无任何针孔,而即使是很贵的玻璃滤色镜也不免有针孔. 其两面镀膜使任两个针孔重合而漏光的几率极小.太阳观察保护膜  AstroSolar TM 已得到PTB-德国国家眼安全标准局的批准. 不同于面市的其他太阳滤色镜,保护膜AstroSolar TM 是由CE 机构按标准EG-Norm  89/686 和EN169/92 测试的(被通知人号0196).与该产品有关的所有步骤均经彻底的测试.镀膜经恒常测试以一如既往地保证使用者的用眼安全.
  
*太阳观察保护膜AstroSolar TM的历史和目标在2000年8月11日前已经向全欧洲的日食观察者售出了1900万片的各种尺寸和规格的该膜,无任何用户受到眼伤害,该生产商已生产太阳保护膜逾12年,有资格宣称该膜在太阳观察上的高度竞争力.该膜将向使用者揭示太阳掩藏的壮观景象,而这些所需的费用只及昂贵仪器的一小部分. 真正专业的太阳观察总是属于那些执拗的业余爱好者,他们可以毫不犹豫地为买1/20λ玻璃滤光镜或2英寸赫歇尔光契(我们均有库存) 付出1000美金.但现在他们可以毫不犹豫地为买1/20λ 玻璃滤光镜或2英寸口径的保护膜AstroSolar TM,而获得同等的精度.由此,太阳观察不再是一桩费力的事,用户可以透过装有保护膜AstroSolar TM 作为廉价滤光镜的天文望远镜享受到业余爱好者的所有乐趣.许多的用户拥有了保护膜  AstroSolar TM 后,均抛弃了老的滤光镜,他们所作的就是要追求一个完全崭新的纯粹的和极具审美价值的太阳,因为有了保了老的旅光镜,他们所作的就是要追求一个完全崭新的纯粹的和极具审美价值的太阳.因为有了保护膜AstroSolar TM天文望远镜在白昼和黑夜有了同样的观察效果.人们总惊奇的是业余爱好者当观察我们这颗最近的恒星---太阳时极易接受平庸的像锐度,但却对于用于其他恒星的观察的天文望远镜的成像质量及其挑剔.
    *产品揭密、 产品品种   保护膜AstroSolar TM由于1999年的日食观察的巨大需求应运而生..在制造工膜具的实验、 以及为了获得绝对均一分子结构的基片膜的处理技术实验中用去了几十英里的薄膜. 更不用说为获得理想的特性而作的相关处理 、 退火和双面镀膜中所用的薄膜中所用的薄膜,大体上该生产商能提供以下两类薄膜产品,它们对用户的望远镜的成像质量毫无影响. (1) 保护膜AstroSolar TM用于太阳观察和照相;  (2)低密度保护膜TurboFilmTM  用于昂贵光学设备的夜间的保护:屏避灰尘、擦碰、膜层缺陷、潮湿对镜筒和镜子表面的影响、以及其最终而不是至少隔绝了镜筒中的空气流.
  
    *保护膜AsrosolarTM   照相用薄膜  由于激进的太阳摄影者总批评说: 视密度D=5对于目镜投影来说太暗了,该生产商相应地提供两种保护膜  AstroSolar TM  (1) AstroSolar TM  照相用薄膜,视密度D=3.8  可在用目镜投影提供、或用该生产商即将面市的4倍平场氟化钙转像器时,缩短曝光时间. 4倍平场氟化该转像器采用了APQ三片式物镜和阿贝目镜的创始人设计的光学系统.在120mm直径的平视场中,该2英寸4倍平场氟化钙转像器获得的线分辨率十倍于最好的蔡司--阿贝(ZEISS ABBE) 或潘太克斯(PENTAX)目镜. 就如保护膜AstroSolar TM   一样,巴德4倍平场氟化钙转像器将是使用所见的最锐利的 “巴罗”(BARLOW)镜.
     AstroSolar TM 照相用薄膜D=3.8可提供短至1/1000秒的曝光时间.如无中性灰滤色镜,千万不要用AstroSolar TM 照相用薄膜作目镜观察.
二、  性能及规格
*该膜特别适用于做双筒望远镜、天文望远镜、照相机和摄像机的物镜用太阳滤光片.
*该膜是特别制造的无条纹和无疱点的箔 (非聚酯薄膜).
*该精密薄膜的开发是在核子和粒子物理实验室中进行的.由于其极高度的均匀性,该箔获得了具有极高平面平行度的玻璃滤光镜的光学特性.
*该箔两面的高密度镀膜保证了高度一致的滤光能力而无任何针孔效应, 因此可致极明晰的具有中性密度性质的太阳像. 太阳显现其真实的"色彩”: 中性白色,而非蓝色或橙色.
*太阳观察保护膜  AstroSolar TM 的镀膜置于恒常的质量控制下.其在直接的太阳观察时的反射特性和安全性不断地受到PTB---德国国家眼安全标准局的测试. 由于符合安全标准而被授予"CE"标志
*太阳观察保护膜AstroSolar TM 被卡尔—蔡司公司(CARL/ZEISS)选作为千百万日食观察者的滤光保护膜.
以下是德国BAADER 主页内容：

[size=-1]The new BAADER AstroSolar™ Safety Film(neutral density 3.8 and 5.0) A New Standard in Solar Filters(review in Sky&Telescope 9/2000) Baader Planetarium is proud to present a new safety film for solar observation. It is made for the construction of high-quality objective-filters for observing the sun with telescopes, binoculars, camera or video-lenses. This foil is CE-tested and reduces the intensity of sunlight by 99.999% (neutral density 5.0). Making an inexpensive filter cell for BAADER AstroSolar TM Safety Film [size=-1]The film must be mounted flat and free of any tension - Only this will provide first class Solar images. The quality of this patent pending material is so high that any wrinkles or strain on the film will lead to a very noticeable deterioriation of optical quality. [size=-1]When mounted carefully, AstroSolar TM Film can reach the quality levels of truly precision polished glass plates (not to compare with several glass filters made of ordinary window glass w/o ever having seen a polishing machine). The "Cylinder" [size=-1]At first you have to produce a cylinder of cardboard, to exactly match the outer circumference of your Telescope tube or dew cap. In order to achieve this, cut a whole number of cardboard layers, approx. 5 -6cm (2 inches) wide. Wrap one piece of cardboard around your dew cap or lens cell and glue one end onto the other. [size=-1]Fasten a second and third a.s.f. layer of cardboard in the same manner, until you have manufactured a stiff roll of cardboard, approx. 4 - 5mm thick. Watch out that the finished "cylinder" will slide snuggly over the tube and that it will be easy to slide it on and off the telescope. [size=-1][size=-1]Hint:For telescopes with smaller aperture one could try to find an appropriate "poster tube" and cut off a piece of approx. 5 - 6cm length. Variations in diameter could be egalized by using adhesive felt liner or by gluing Kork pads into the paper tube. The "Filter Cell" [size=-1]Cut out two rings of cardboard (each having 1 - 2mm thickness). The outer diameter of the ring - shaped cardboard should match the outer diameter of your fabricated "cylinder". The inner diameter should correspond to the actual aperture of the instrument (some mm less may improve on image quality, due to hiding sunken edges on imported objective lenses). [size=-1]After having prepared two such rings, both should be equipped on adjacent sides with a large number of small cutouts of double tape along the outer circumference of both rings. Now comes the tricky part - how to get the Solar film onto the taped ring w/o wrinkles or ripples. The film must not be scratched - so put one sheet only of Kleenex (or other soft tissue) onto a flat table. Tape the Kleenex onto the table so that this part is streched out evently and cannot move on you. Only now put a square piece of film - (precut to the size of the cardboard-rings) onto the piece of soft tissue. Do not tape the film and do not strech it! Just let it rest relaxed and flat on the Kleenex. [size=-1]Now take the first cardboard ring and lower it straight down onto the film until every double tape clipping made contact with the film. Turn this package around, tape the other ring onto the opposite side and cut away the overleaf. Now your AstroSolar TM film should be mounted free from strain and wrinkles between the two cardboard rings. Finally glue this "filter holder" onto the prefabricated "Cylinder". Now your "Do it Yourself" filter is ready. Enjoy it - you just saved about US$ 100 - for the filter cell alone. [size=-1]When covering a larger Newtonian or Schmidt-Cassegrain Telescope for Solar Observation, then "Less may be More"! Do not try to make a filter as large as the the telescope aperture itselve. The bigger aperture will greately be compromized by air turbulence and secondary mirror obstruction. Rather produce an "off axis filter cell", to observe the sun with a smaller (but much improved) telescope, wereby an ordinary reflecting telescope may be raised in sharpness and definition to the level of a good refractor. Please observe the following safety precautions with EVERY solar observation [size=-1][size=+1]1.Prior to each and every solar observation session, check the filters fit and - if necessary - tape it to prevent slipping. Never use the filter at the eyepiece, only attach it onto the front of the objective, in front of the Schmidt-plate (SC-owners) or in front of the tube of a Newtonian-telescope. Otherwise it can become dangerously hot inside your instrument and inside your eyes. [size=-1][size=+1]2.If you use a binocular, protect both objectives with a filter. Also make sure, that the viewfinder of your telescope is properly covered, either with foil or with the original dust cover. Unprotected views through your finderscope would have the same catastrophic consequences for your eyes as a look through the main telescope itself! [size=-1][size=+1]3.A filter made of foil is relatively resistant to breackage in comparison to a glas filter. However, care should be taken with sharp pointed objects. [size=-1][size=+1]4.Emphasize the importance of caution to those observing with you, especially children. Intentionally removing or damaging the filter can endanger their eyesight. This is no place for jokes. Never leave the telescope outside unattended during the daytime!

[size=-1]Laserinterferometric Wavefront Test with Baader Astro Films (download this page as a pdf-file)

[size=-1]The following stringent test has been performed by an independent optical Institute in Germany which tests amateur telescope optics. 1. Test Method In order to simulate a telescope in the test arrangement, the uncoated films were mounted between two reference optical windows of highest accurracy and measured in transmission in a parallel beam set up. The influence of the wave front deformation caused by the film was then registered by a Zygo-Laserinterferometer at a wavelength of lambda = 632.8 nm. Aside of the Interferogram itselfe (first row), the wavefront deformation is presented in relief maps (four graphs). As an addition, the point spread function (PSF - second row of images) has been recalculated for each measured film. These images represent the Airy disc of a star as it would be seen at the focus of a telescope system. The registered wave front deformations also served to verify the relevant quality criteria, such as P-V and RMS-values, as well as the Strehl ratio, given below the Airy disc renditions.

[size=-1]2. Rating the films as "optical Windows" Three film samples and the readings for the reference system w/o film are presented in the table No.1 below. Three substrates have been tested: [size=-1]Plain, uncoated AstroSolar™ film (annealed). The film had been mounted carefully between two rings of cardboard. [size=-1]Plain TurboFilm™ (annealed), mounted frameless between the reference-plates. [size=-1]Original Mylar of 12ym thickness (48 gauge), mounted frameless between the reference-plates. [size=-1]Both substrates from Baader Planetarium tested out to be diffraction limited under all aspects of the measurements across the full testfield of 100 mm diameter. In terms of RMS-values and strehl-ratio both materials surely outperform many Amateur-Telescopes. In the contrary, in spite of frameless mounting - free from stress and ripples, the Mylar-sample deteriorated the laser wave front given by the Zygo Interferometer. The wavefront deformation was notably stronger than it would be tolerable for a diffraction limited optics. The test-results give evidence that the Films from Baader Planetarium are very well apt for optical applications. Most probably they outperform by far a good amount of the so called "affordable Glass-filters" on the market. The test results also attest to the fact that interferometric values are strongly influenced by the way in which the films are mounted or "framed". When producing an AstroSolar™ filter, care should be given to avoid the film to be folded or put under tension. Any stress on the annealed film would deteriorate the transmitted wavefront, notably reducing the image quality.

[size=-1] [size=-1]Reference system [size=-1]w/o film [size=-1] annealed AstroSolar™ non-metallized [size=-1] annealed TurboFilm™ [size=-1] original Mylar™ [size=-1] Airy disc of refernce system [size=-1]w/o film, Strehl ratio 99.9% [size=-1] Airy disc with AstroSolar™ Strehl ratio 94.1% [size=-1] Airy disc with TurboFilm™ Strehl ratio 96.8% [size=-1] Airy disc with Mylar™ Strehl ratio 57.2% [size=-1] Reference w/o film [size=-1] AstroSolar™ [size=-1] Turbofilm™ [size=-1] Mylar™

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