[Laser] Lunar downlink

[J. Forster]

Glenn Thomas wrote:

[snip]  I think I've seen that same report. Receiving 0.01 photons per pulse

> means that they got one photon for every hundred pulses. I don't
> think there's any such thing as a fraction of a photon that remains a
> photon! It's still not clear what the potential contribution of
> thermal noise is to this system.

Essentially nothing if the photocathode of the PMT was at dry ice or below. The
operating wavelength was ruby, around 700 nm as I said before. How many mirrors do
you see glowing in the visible at room temperature.?

> An even better approach would be to track the earth via one of the
> water based infrared spectral lines. They aren't affected much by night & day.

It's hard to get a good, stable centroid. A laser beacon would be a whole lot
easier, IMO.

-John