On Wednesday, May 25, 2016 at 12:11:06 PM UTC+12, Robert Clark wrote:
Thanks for that. They discuss inflatable mirrors. According to the refs,
they should work for infrared wavelengths but couldn't maintain sufficient
accuracy for optical wavelengths. They be tested though if they can form
large infrared mirrors. Is there a limit to their size? Could they be made
large enough to image extrasolar planets in the infrared?

Bob Clark

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"William Mook" wrote in message
...

http://www.techbriefs.com/component/...machinery/7062

http://citeseerx.ist.psu.edu/viewdoc...=rep1&type=pdf

https://www.google.com/url?sa=t&rct=...73rrKo2WfKxvxg

The technology described is not accurate enough for imaging down to the resolution limit at short wavelengths. Newer technology does better.

http://www.sciencedirect.com/science...05109809001721

That is, even though thin film mirrors were not good for astronomical objects better than they can be imaged here on Earth through an atmosphere with smaller optics. Thin films are far better than naked eyesight corrected to 20/20 which goes down to an arcminute without a telescope.

The thin film concentrators are perfectly suited for concentrating sunlight! The image of the sun approximates the size of the moon (hence eclipse) of 32 arc minutes - about half a degree.

So, these films are perfectly suited to concentrate the intensity of sunlight 46,225x - the limit possible with conventional paraboloid concentrators. This reproduces the surface of the Sun on Earth! In my tests I've limited concentrations to 2,600x solar intensity due to limitations in the handling of heat.

(see figure 3 in my patent)

http://www.google.com/patents/US20050051205

Of course as efficiencies improve, intensities can rise to that of the solar surface.

The advantages of concentration is clear. At 1600x solar intensity at Earth, the solar image is 1/40th the diameter of the concentrator. So, a 40 meter diameter concentrator focuses a solar image onto a 1 meter diameter receiver. That receiver can reduce the image further, to about 500 mm by destroying the image, using nonimaging optics. This is 719,079,5 Watts of solar energy focused on to a 500 mm wafer - 1963.4 sq cm in area. 875.52 Watts/cm2.

The wafer costs $29,500 and the film 9 um average thickness, and consisting of a reflective sheet bound to a transparent sheet, masses 45 kg and costs $75. The wafer is 950 um thick and weighs 488 grams. It forms its own nano-satellite with all systems integrated on the wafer, including holographic optics on the 'dark' side that produces a laser beam at very high efficiency. Solar pumped laser energy is beamed with a secondary thin film mirror to any point on the Earth visible to the secondary. The

http://www.microfabrica.com

This is a lenticular device

http://www.lgarde.com/assets/content...af-98-I501.pdf

A 40 meter diameter reflective paraboloid that's 14.14 meters height has a focal point 28.28 meters from the origin of the paraboloid.
40 m diameter
14.14 m height
28.28 m focal point
3515.10 sq meters - film (1757.55 sq m transparent, 1757.55 sq m reflective)
8884.42 cubic meters - gas.

A transparent paraboloid has its origin at that focal point. It has attached to it a 1 meter diameter hyperboloid inflatable secondary made of reflective film that produces collimated beam which illuminates the 0.5 meter diameter wafer attached to the origin of the reflective paraboloid. The light is segmented into colours and processed by bandgap matched solar pumped thin film lasers at an overall efficiency of 80% (see figure 17 in my patent) and pass to an active optical film that operates at the focus of a second lenticular CONVEX reflector 4 meters in diameter with a 167 mm height - 334 mm including the transparent and reflective portion - with a 6 meter standoff distance. This system is deployed at the same time as the larger system, and floats behind it imaging the aperture of the holographic system that directs the laser beams coming out the rear of the larger solar concentrator to any point on the surface of the Earth. The smaller concentrator images the Earth below horizon to horizon projecting that image on to the wafer efficiently.

A terrestrial reflector 1.27 meters in diameter collects laser energy beamed from the 4 meter transmitter. A guide laser is beamed at the satellite as it passes overhead, and a laser connection established.

http://www.telescope.com/Orion-50-Mo...ope/p/9162.uts

http://lasermotive.com

The receiver efficienctly converts laser energy to DC electrical power which drives a Tesla Power wall with 120 kW supercharger technology. So, it can charge a 6.1 kWh Power Wall up in about 3 minutes. It can send six beams simultaneously to Earth, and so, serve 86,400 users anywhere on Earth per satellite. Power is modulated by pulse width modulation of the laser beam.

The system can efficiently link receiver and transmitter over a distance of 7,570 km. A 2 hour sun synchronous orbit above the terminator (sunrise sunset path) of Earth stays in constant sunlight, and covers the entire Earth every 12 hours. The main reflector is perpendicular to the flight path and parallel with the Earth's surface, facing the sun. The secondary reflector is tilted (yaw) at 45 degrees to the center of rotation of the primary, and rotates (pitches) to maintain level flight along the flight path. Any receiver with clear sky above the horizon of the spacecraft can signal and power beamed to the ground station efficiently. The beam itself can be modulated and the satellite operate as a broadband store and forward system for messages between users

719,000 Watts x 8766 hours = 6.3 million kWh per year

x$0.18 per kWh = $1.134 million per year

20 years at 8.5% discount = $10.73 million present value the day it switches on.

A small satellite like this, is a proof of concept version. It masses less than 100 kg - and can be put on orbit as a secondary satellite for $300,000 - and cost less than $300,000 to build.

http://www.spaceflight.com/spaceflig...lite-industry/

The ground station costs another $150,000 - but this could come down as the number of 50" reflectors produced rises. To about $15,000 -

Each power wall produces 500 Watts over 12 hours before being recharged again. With ten power walls at $3,000 each being served by one receiver, costs can be quite low.