在国外网站上看到关于改造天文摄影专用相机的帖子
How to Make a Hydrogen Alpha FilterFire is hypnotic. Sit any group of campers around a nighttime fire, and you’ll notice their attention drawn by the constantly shifting interplay of form and color. Observing the sun offers that same fascination, enhanced by the knowledge that the flames of the sun support all life on Earth. The roiling, popping, swirling outer surface of the sun is best seen with one particular narrow part of the spectrum, the hydrogen alpha line, which is one particular wavelength of red light. The wavelength is 656.28 nanometers, or 656.28 billionths of a meter. The principles behind a filter that will isolate that wavelength are clear.Things You'll Need2 high-precision front surface mirrors Precision adjustable mounting stages Precision translation stage Bandpass filterInstructionsPut the mirrors in the mounts and set up the mounts so the reflective sides of the mirrors face each other. This kind of cavity is called a Fabry-Perot etalon. One mount should be placed on the precision translation stage. Adjust the mirrors so they face each other perfectly. You can do this by shining a laser from the back side of one through the pair of mirrors and looking at the transmitted beam. Adjust the angle until any transmitted beams are right on top of each other. Move the precision stage to adjust the spacing for maximum transmission at 656.28 nanometers. The transmission for a Fabry-Perot peaks when the spacing is equal to an integral number of half-wavelengths. That is, the distance is equal to m x lambda/2, where lambda is the wavelength and m is a whole number. M will be, in general, a very large number. For example, to filter for hydrogen alpha light with a spacing around 25 mm, m would be 76,187. Put a blocking filter in front of your mirror assembly. The blocking filter is necessary because when your Fabry-Perot is perfectly set up to enhance the transmission of 656.28 nm hydrogen alpha light for m = 76,187, it will also enhance the transmission of 657.89 nm light with m = 76,000, for example. So you put a less precise blocking filter in front of your etalon to get rid of background wavelengths that would otherwise make it through.Tips & WarningsIf you work through the numbers, you will see that you need extremely high precision for the mirror surfaces, the alignment and the spacing. That’s why this isn’t a typical do-it-yourself project. Although hydrogen alpha filters are expensive, you may find it more cost-effective to buy.
谁能翻译一下怎么制作专用滤镜 只看了标题，传说中的HA日珥镜。。。改相机比较难吧，会把ccd烧掉的？？ 文章说需要两个高反镜片来构建一个Fabry-Perot etalon，然后描述了怎样构建，根据波长设定距离等等。
最后说很难做到不如去买一个现成的日珥镜。。。 我看到有些天文摄影改装CCD前的一片滤镜，用作深空摄影。看着个貌似是这个意思。。。。 就是说的巴德BCF到底是个啥玩艺？ 本帖最后由 xujun 于 2012-5-26 18:29 编辑
Ha滤镜别想DIY了,那东西所需的精度不是业余条件能弄出来的. xujun 发表于 2012-5-26 18:26 static/image/common/back.gif
Ha滤镜别想DIY了,那东西所需的精度不是业余条件能弄出来的.
那请问您知道HA滤镜的通过频率吗？我倒是有一些带通滤镜，就是不知道深空摄影需要的具体是哪个波段 两片高反镜之间的距离 = m x lambda/2
lambda是波长，m是个巨大的常数，对于HA来说m=76187。
这个东西对于普通玩家来说基本上是不可能diy的：
1.它需要高精度的高反镜弄不到。
2.把这俩镜子完全平行放置普通人做不到。
3.精确的距离也放不准。
所以这个方法来做日珥镜只是理论上的。 六阿六 发表于 2012-5-26 22:31 static/image/common/back.gif
两片高反镜之间的距离 = m x lambda/2
lambda是波长，m是个巨大的常数，对于HA来说m=76187。
好吧。。。。
页:
[1]