Power transmission device

A power transmission device for transmitting electric power optically to ote locations. The device includes a laser for generating a laser light beam and a optical glass monofilament having a glass core and a outer cladding layer designed to convey the light beams directed into one end of said monofilament to the other end thereof. Means are provided for directing the laser beam into the receiving end of the monofilament at a predetermined angle which causes the light beam to exit from the other end of the monofilament at the base predetermined angle in a conical annulus of light. A conical reflector is disposed within the conical annulus of light exiting from the exit end of the fiber optical monofilament and has a surface that intercepts the light beams within the conical annulus and reflects them along a different path. Disposed around the conical reflector is a plurality of photovoltaic cells in a position to intercept the reflected light beams and to convert the light beams to electric current. The photovoltaic cells are connected in series to increase the amount of voltage produced by the transmission device.

BACKGROUND OF INVENTION 
This invention relates to a device for providing electric power to remote 
locations. More particularly, this invention relates to a device for 
providing electric power in a remote location where electric wires would 
disturb balance within a electro-magnetic environment and where batteries 
are not adequate. In testing missile telemetry packages, it is necessary 
to provide a source of electricity to test the reaction of various devices 
to electromagnetic fields. In this environment, any conductive cables 
would change the field and would, therefore, not give accurate test 
results. 
SUMMARY OF THE INVENTION 
It is an object of the invention to provide a device for delivering 
electric power to a remote location for testing devices' reactions to 
electromagnetic fields without disturbing the electromagnetic fields. 
An alternative to batteries for delivering power to such devices is to 
utilize a fiber optic filament to direct light to photovoltaic cells 
located within the missile that is in the electro-magnetic environment. In 
this system photovoltaic cells convert the optical power into electrical 
power. Photovoltaic cells typically provide voltages in the range of 0.5 
to 1.0 volts. Where a higher voltage is required a plurality of 
photovaltic cells are connected in series. However, in connecting the 
cells in series it becomes difficult to distribute the light from the 
optical filament equally or uniformly to all of the cells. If the light is 
not distributed equally, and one or more cells do not receive the same 
optical power as the other cells, these cells will not produce as high a 
current as the others. This means that the cell receiving the least 
optical power will set the current limit for all of the cells since they 
are connected in series. Thus, an unequal distribution of light causes a 
loss in the overall efficiency of all the cells. 
The invention provides a means to equally distribute optical energy by 
optical filament to a plurality of series-connected photovoltaic cells in 
order to produce the required voltage in locations which are compact and 
in restricted space locations. 
In the invention a laser beam of light is directed into a receiving end of 
a glass optical monofilament at an angle to its longitudinal axis and the 
beam exits from the other end of the optical monofilament in a conical 
annulus of light having the same angle as the angle at which the light was 
directed into the optical monofilament. Means are provided to intercept 
the conical annulus of light and to direct it uniformly upon a plurality 
of series connected photovoltaic cells to generate the required electric 
power.

DETAILED DESCRIPTION OF THE INVENTION 
Referring now to FIG. 1 which shows a fiber optic monofilament 10, which 
has a glass core 12 and a counter cladding 14 of glass to permit 
monofilament 10 to transmit light beams from one end to the other end. At 
one end of monofilament 10 a laser beam 16 from laser 15 (see FIG. 5) is 
directed into the core of the monofilament 10 at an angle .theta. to the 
longitudinal axis 20 of monofilament 10. Laser beam 16 is transmitted from 
one end of monofilament 10 to the other end and exits from the other end 
of the monofilament in the form of a conical annulus 22 having a conical 
angle to the longitudinal axis 20 of the monofilament. It should be noted 
this angle is always the same as the angle at which laser beam 16 entered 
the core of the monofilament. Furthermore, the light beam exits from the 
end of the monofilament in a conical annulus 22, with the light beam 16 
evenly distributed throughout the annulus 22. 
In FIG. 2 is shown a power converter 24 which comprises a conical reflector 
26, centrally disposed within a ring of solar cells 28. Solar cells 28 are 
photovoltaic and convert light shining upon them into electrical current. 
The solar cells 28 are held in place by a bonding agent 29, as seen best 
in FIG. 4. 
Referring now to FIGS. 3 and 4 wherein it is seen that conical reflector 26 
has its apex disposed within conical annulus 22 and its base disposed 
outside of the annulus in a position to intercept and reflect the light 
beams disposed in conical annulus 22. Light beams in conical annulus 22 
are reflected by the conical reflector 26 to impinge evenly upon the 
surfaces of solar cells 28. Since the laser beam is evenly distributed 
within conical annulus 22, its light is evenly reflected upon the cells 28 
to provide an even distribution of the light beams thereon and, to provide 
an even power generation throughout all of the solar cells 28. 
As can be seen best in FIG. 4, solar cells 28 are arranged in overlapping 
relationship with each other, so as to provide an even disposition of the 
solar cells within the power converter 24. Solar cells 28 are held in 
place by a bonding agent 29 which is selected to withstand any heat that 
may be generated within the solar cells 28. 
As seen best in FIGS. 5 and 6, the light beams in annulus 22 are reflected 
onto cells 28, which are wired in series, with the front of each of the 
cells having a positive contact 32 which is connected by wire to the back 
side of the adjacent solar cell 28 as at 34. Since each of the cells 28 
generate a small voltage and current the plurality of cells will produce 
an additive or higher voltage available at output terminals 30 and 30' 
whenever the photovoltaic cells are connected in series as illustrated in 
FIG. 6. 
However, where photovoltaic cells are connected in series as illustrated it 
is very important that each of the cells receive the same amount of light 
as do the remaining cells. If the cells do not receive the same amount of 
light, the cell receiving the least optical power will set the current 
limit for all the cells when they are connected in series. Such uneven 
distribution of light causes a loss of efficiency of the cells in 
producing electrical current.