To study the heavens, it's all about the photons. "We in astronomy are always greedy. We want every photon we can collect." Drew Phillips, astronomer at University of California Observatories. More photons, he says, basically means more science about incredibly faint, distant objects.

And that's where the optics problem comes in. Because incoming light reflects off several mirrors before it comes out the business end of a telescope. And mirrors aren't perfectly reflective. The traditional mirror coating, aluminum, reflects only about 90 percent of light. Bounce that light around a few times in a telescope, and you lose valuable photons.

"The throughput, the actual number of photons that are detected in the end in a modern spectrograph, you're doing good if you get thirty percent."

So you want the most reflective material for your mirrors. Like silver, which reflects 97 to 99 percent of visible and infrared light, respectively. Big improvement over aluminum. But silver's got problems too. "It is finicky. It's subject to tarnish, and oxidation, and corrosion."

So Phillips and his team have borrowed a trick from the computer industry, called atomic layer deposition. The technique allows them to take a silver-coated mirror—and coat it with extremely uniform layers of transparent aluminum oxide, to protect against corrosion.

And unlike the small-scale atomic deposition used in the electronics industry, this new machine--recently installed in a lab at U.C. Santa Cruz—is scaled up to coat mirror segments up to a meter in diameter. Meaning you could coat all 500 mirrors of a state-of-the-art telescope—like the planned Thirty Meter Telescope—in a matter of months. [Journal of SPIE]

When put to use, these better mirrors might allow astronomers to capture more photons… and shed more light—literally—on faraway galaxies and stars.

--Christopher Intagliata

[The above text is a transcript of this podcast.]

中文翻译

为了研究天堂，它就是光子。 “我们天文学总是贪心。我们想要收集每一个光子。” Drew Phillips，加州大学天文台的天文学家。他说，更多的光子基本上意味着更多科学关于难以置信的微弱，遥远的物体。


这就是光学问题出现的地方。因为入射光在从望远镜的商业端出来之前从几个镜子反射回来。镜子不是完全反光的。传统的镜面涂层铝仅反射约90％的光。在望远镜中将光线反射几次，就会失去宝贵的光子。


“吞吐量，在现代光谱仪中最终检测到的光子的实际数量，如果你获得百分之三十，你就会做得很好。”


所以你想要镜子最反光的材料。像银一样，分别反射97％到99％的可见光和红外光。铝的重大改进。但是白银也有问题。 “这很挑剔。它会受到玷污，氧化和腐蚀的影响。”


因此，菲利普斯和他的团队借用了计算机行业的一种技巧，称为原子层沉积。该技术允许他们采用镀银镜面，并涂上极其均匀的透明氧化铝层，以防止腐蚀。


与电子行业中使用的小规模原子沉积不同，这台新机器最近安装在英国的一个实验室。圣克鲁斯（Santa Cruz）被扩大到覆盖直径达1米的镜子段。这意味着你可以在几个月内涂上最先进的望远镜的所有500个镜子 - 就像计划中的三十米望远镜一样。 [SPIE期刊]


当投入使用时，这些更好的镜子可能会让天文学家捕获更多的光子......并且在遥远的星系和恒星上发射更多的光。


--Christopher Intagliata