1. An optical device, comprising:
an aplanatic optical imaging system including:
a) a segmented primary reflective element defining an entrance aperture and having a plurality of aspherical primary reflective segments; and
b) a segmented secondary reflective element having a plurality of aspherical secondary reflective segments,
wherein primary and secondary reflective segments are pair-wise correlated so that a primary reflective segment images a field of view onto a corresponding secondary reflective segment, and wherein the secondary reflective segment images the corresponding primary segment onto an exit aperture; and
a target element positioned proximal to a vertex of the primary reflective element.
2. The device of claim 1, wherein the exit aperture is substantially contiguous with the vertex of the primary mirror element.
3. The device of claim 1, wherein the target element comprises a solar cell.
4. The device of claim 1, further comprising a cover positioned proximal to the entrance aperture.
5. The device of claim 1, wherein the plurality of primary and secondary reflective segments are radially symmetric with respect to a central axis.
6. The device of claim 1, wherein one of the secondary reflective segments is coplanar with the entrance aperture.
7. The device of claim 1, wherein the space between the primary and secondary reflective elements comprises air.
8. The device of claim 1, wherein the space between the primary and secondary reflective elements comprises a dielectric material with an index of refraction, n.
9. The device of claim 8, wherein n is in a range from about 1.3 to about 1.5.
10. The device of claim 1, further comprising a non-imaging concentrator having an entrance aperture disposed proximal to the exit aperture.
11. The device of claim 10, wherein the non-imaging concentrator is one of a \u03b81\u03b82 concentrator, a tailored non-imaging concentrator or a flow line concentrator.
12. The device of claim 10, wherein the non-imaging concentrator comprises a first dielectric material having an index of refraction different from the material defining an interior of the aplanatic optical imaging system.
13. An optical device, comprising:
an aplanatic optical imaging system including:
a) a segmented primary reflective element defining an entrance aperture and having a plurality of primary reflective segments; and
b) a segmented secondary reflective element having a plurality of secondary reflective segments, and
a target element positioned proximal to an exit aperture,
wherein primary and secondary reflective segments are pair-wise correlated so that light impinging on a primary reflective segment is focused onto a corresponding secondary reflective segment, and wherein the secondary reflective segment images the corresponding primary segment onto the exit aperture such that the target element is substantially uniformly illuminated.
14. The device of claim 13, wherein the primary reflective segments and the secondary reflective segments are aspherical.
15. The device of claim 13, wherein the target element includes a solar cell.
16. The device of claim 13, further comprising a non-imaging concentrator having an entrance aperture disposed proximal to the exit aperture.
17. The device of claim 13, wherein the exit aperture is proximal to the vertex of the primary reflective element.
18. A method of concentrating light onto a solar cell, the method comprising:
positioning an aplanatic optical imaging device to receive incident light from a light source, the device including a segmented primary reflective element having a plurality of primary reflective segments, and a segmented secondary reflective element having a plurality of corresponding secondary reflective segments,
reflecting incident light by the primary mirror segment s onto corresponding secondary mirror segments; and
reflecting the reflected light by the secondary mirror segments onto a target cell, wherein the target cell is substantially uniformly illuminated by the incident light.
19. The method of claim 18, wherein the device further includes a non-imaging concentrator position proximal to the target cell, and wherein the method further includes concentrating the incident light reflected by the secondary mirror segments onto the target cell.
20. The method of claim 18, wherein the light source is the sun, and wherein the method further includes repositioning the device so as to track the motion of the sun such that incident light from the sun is received within an acceptance angle of the device.
21. The method of claim 13, wherein the primary reflective segments and the secondary reflective segments are aspherical.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A drive arrangement of an agricultural machine comprising a combustion engine connected to both a control unit configured with a default value of engine RPM, and a power take-off (PTO) transmission having selectable transmission steps which is further connected to a power take-off having a PTO output that is associated with a sensor for determining the RPM of the PTO output, where the control unit is coupled with a first operator input device to influence the RPM of the combustion engine and a second operator input device that is adjustable to set a maximum RPM of the PTO output, the control unit being configured to regulate the RPM of the combustion engine during operation based on the input of the first operator input device and to limit the RPM of the combustion engine based on the input of the second operator input device, the limit of the RPM of the combustion engine being limited to the maximum RPM value entered on the second operator input device based on a measured value of the sensor.
2. The drive arrangement according to claim 1, further comprising an indicator device coupled with the second operator input device and which displays the selected maximum RPM of the PTO output.
3. The drive arrangement according to claim 1, wherein the sensor measures the RPM of the combustion engine and the control unit is configured to calculate the RPM of the PTO output based on the measurement of the sensor and a known PTO transmission ratio.
4. The drive arrangement according to claim 1, further comprising a third operator input device connected to the control unit, the third operator input device inputting at least one of a maximum RPM of the combustion engine and a maximum propulsion speed of the machine, the control unit being configured to limit the RPM of the combustion engine so that neither the maximum RPM of the PTO output nor the maximum RPM of the combustion engine or the maximum propulsion speed of the machine is exceeded.
5. The drive arrangement according to claim 1, wherein the PTO output can be switched on and off and the control unit is configured to deactivate the maximum RPM of the combustion engine entered via the second operator input device when the PTO output is switched off.
6. The drive arrangement according to claim 5, further comprising a PTO shaft switch configured to switch the PTO output on and off, the control unit being configured to recognize a deactivated PTO output based either on the PTO shaft switch or on the sensor.
7. The drive arrangement according to claim 1, further comprising the PTO transmission having a plurality of of transmission steps, the control unit being configured to limit the RPM of the combustion engine to prevent the RPM of the PTO output from exceeding a pre-determined percentage above an allowed RPM of the PTO output associated with each respective transmission step of the PTO transmission.
8. The drive arrangement according to claim 1 incorporated into a tractor.