@Bill Otto Lived next to NASA Huntsville;became manned spaceflight SME 的回答
This was actually a problem that we were asked to look at. A satellite had been deployed badly and the solar panels were not pointed at the sun. They were pointed somewhat down. Could we charge the batteries with a laser from the ground or from ABL (the Airborne Laser YAL-1)?
这需要我们考虑的实际问题。卫星部署不善，太阳能电池板未对准太阳，而是朝着下方。我们可以使用地面或ABL（ the Airborne Laser YAL-1 ,机载激光YAL-1）上的激光为电池充电吗？
The Airborne Laser. The laser beam was brought up to a 1.5 meter diameter telescope/gimbal at the nose of the aircraft. Thanks to Iain McClatchie for suggesting this photo.
机载激光。 激光束被指向飞机机头的直径1.5米的望远镜/万向节。 感谢Iain McClatchie推荐这张照片。
Close up of the telescope used on the front of the Airborne Laser. Mainly you see the optically coated conformal window.
First, solar panels on a satellite convert light to electricity. As long as the light’s wavelength is somewhere between 350nm and 550 nm, it will work. Solar panels do not care whether the light is coherent or collimated or diffuse. If the right wavelength is delivered in sufficient quantities, we are good, and the batteries will charge. We only needed enough charge to wake up the satellite to respond to ground commands.
首先，卫星上的太阳能电池板将光转换为电能。 只要光的波长在350nm至550 nm之间，它就会起作用。 太阳能电池板不在乎光线是否是连贯的，准直的或散射的。 如果波长正确数量有效，那就很好，电池就会充电。 我们只需要足够的电荷就可以唤醒卫星以响应地面命令。
Tracking and pointing the beam at a solar panel was already worked out because we could hit a missile with a high power laser. Atmospheric correction using adaptive optics was already worked out. So that left the next question: what power level is needed?
The Airborne Laser successfully tracked and pointed a laser beam on boosting missiles at a distance, destroying the missiles. The distance was long enough to require atmospheric correction using adaptive optics. Beam shown is an artist’s concept. Actual beam was invisible.
机载激光成功地跟踪并对准了远距离发射的导弹并摧毁。 该距离很长，需要使用自适应光学器件进行大气校正。 显示的光束是艺术上的概念。 实际的光束是看不见的。
There is about a 2–3% illumination-to-electricity efficiency, due to solar panel (about 10–15% efficiency) technology and we would have to illuminate a circle somewhat larger than a solar panel instead of just the solar panel itself. If 10 kilowatts of electricity is needed to recharge the batteries, then we would need 300 to 400 kilowatts of laser power in the right waveband.
光转换为电的效率大约为2-3％， 由于太阳能电池板（效率约10–15％）技术，我们将不得不照亮一个比太阳能电池板稍大的圆圈，而不仅仅是太阳能电池板本身。 如果需要10千瓦的电来为电池充电，那么在正确的波段中我们将需要300到400千瓦的激光功率。
A typical solar panel configuration for a satellite.
A COIL (chemical oxygen-iodine laser – used on the Airborne laser) puts out a beam at 1.315 microns. The overtone of COIL is at 658 nm. (You can force the laser to work at double the frequency of the fundamental transition line, but with a reduction in power.) The COIL overtone wavelength was still too long for our solar panel. Doubled YAG (yttrium aluminum garnet) is a much better wavelength for the solar panel.
COIL（ chemical oxygen-iodine laser ，化学氧碘激光器，用于机载激光）发出1.315微米的光束。 COIL的波长是658 nm。 （您可以强制激光器以基本过渡线的频率的两倍工作，但这会降低功率。）对于我们的太阳能电池板，COIL的波长仍然太长。 对于太阳能电池板，加倍的YAG（ yttrium aluminum garnet ，钇铝石榴石）的波长要好得多。
COIL laser schematic. Image credit: Recent Developments and Current Projects in HEL Technology: Harro Ack…
Assuming 50% conversion of the YAG 1064 nm line to 532 nm, we would need about a megawatt of YAG to convert to about 400 kW of green light. A YAG laser uses diodes to pump the gain medium and thus needs a lot of electricity. There are large ground based telescopes that could project the beam without ionizing the air, and we felt ABL was about large enough to do it also. We were not sure we could get enough electrical power to run the pump diodes, but the main problem was getting a YAG laser that powerful.
假设YAG 1064 nm线的50％转换为532 nm，我们将需要大约一兆瓦的YAG才能转换为约400 kW的绿光。 YAG激光器使用二极管泵增益介质，因此需要大量电能。 有很多大型地面望远镜可以投射光束而不会使空气离子化，我们觉得ABL足够大，可以做到。 我们不确定能否获得足够的电力来驱动泵二极管，但是主要问题是如何获得如此强大的YAG激光器。
Typical doubled YAG laser, showing some of the internal beam train components.
We knew that a YAG laser large enough to do the job was not available. We had to say we were sorry but we could not bring the satellite back to life. If we’d had a more powerful green laser at the time, we would then have had only a few minutes on each orbit to put light on the solar panels as the satellite passed over a ground station. Then the next orbit it might not even pass over our hypothetical ground station.
我们知道没有足够大的YAG激光器来完成这项工作。 我们不得不说我们很抱歉，我们无法使卫星恢复活力。 就算我们有一个更强大的绿色激光，那么当卫星经过地面站时，每次轨道只有几分钟的时间将光照射到太阳能电池板上。 然后，卫星运行到下一次轨道时甚至可能没有经过我们假设的地面站。
Satellite can only be seen from the ground for a few minutes each orbit.
So let’s assume we set up ABL with this hypothetical visible laser. We would have to go flying like crazy to be under this satellite on each pass. The batteries of the satellite would get a 5 minute charge at best on each orbit.
因此，假设我们使用这种假设的可见光激光器设置了ABL。 我们将不得不疯狂地飞行，才能在每次通过时我们上方时，我们都一直处于该卫星之下。这样一来 卫星电池在每次轨道中最多充5分钟电。
THEL, an example of a ground based laser. Image credit: Photo
We checked and that simply was not enough charge to power up the satellite and get the solar panels pointed to the sun. So even if we’d had the laser and we could fly it to the right spot, and we could get the green laser fitted into the ABL airplane, it probably would not have been possible to recover the satellite.
I think they had a good idea that this would be the case, but someone told them they had to ask.