Automatic power controller

1. A system for operating one or more light emitting devices, comprising:

at least one light emitting device; and

an amplifier, the amplifier having a gain which has a maximum slope at an equilibrium temperature of the one or more light emitting devices.

2. The system of claim 1 , where the equilibrium temperature is a temperature that the at least one light emitting device operates at when ambient temperature is a prescribed value and the at least one light emitting device is outputting a predetermined irradiance level.

3. The system of claim 1 , further comprising a controller in electrical communication with the amplifier, where the controller includes instructions stored in non-transitory memory for supplying a voltage to the amplifier, the voltage corresponding to a desired irradiance output of the at least one or more light emitting devices.

4. The system of claim 3 , where the amplifier is in electrical communication with a field effect transistor.

5. The system of claim 4 , where the amplifier includes a negative feedback loop electrically that couples an inverting input of the amplifier and an output of the amplifier.

6. The system of claim 5 , where the negative feedback loop includes a thermistor.

7. The system of claim 1 , further comprising a plurality of resistors in a negative feedback path of the amplifier.

8. A system for operating one or more light emitting devices, comprising:

at least one or more light emitting devices;

a variable resistance device in electrical communication with one or more cathodes of the at least one or more light emitting devices; and

a controller in electrical communication with the amplifier, where the controller includes instructions stored in non-transitory memory for adjusting the variable resistance device according to a gain that has a maximum slope at an equilibrium temperature of the one or more light emitting devices.

9. The system of claim 8 , further comprising additional instructions to determine a desired irradiance of the at least one or more light emitting devices.

10. The system of claim 9 , further comprising additional instructions to determine a power to operate the one or more light emitting devices at the desired irradiance.

11. The system of claim 10 , further comprising additional instructions to convert the power to a voltage for operating the variable resistance device.

12. The system of claim 8 , further comprising a thermistor in thermal communication with the at least one or more light emitting devices.

13. The system of claim 8 , further comprising a voltage regulator, the voltage regulator in electrical communication with the at least one or more light emitting devices.

14. A method for operating one or more light emitting devices, comprising:

sensing temperature of a thermal conductor in thermal communication with one or more light emitting devices;

amplifying a voltage representing a desired irradiance output of the one or more light emitting devices according to a gain that includes a maximum slope at an equilibrium temperature of the one or more light emitting devices; and

adjusting power supplied to the one or more light emitting devices according to the amplified voltage.

15. The method of claim 14 , where the amplifying is performed via non-transitory instructions of a controller.

16. The method of claim 14 , where the amplification is performed via an operational amplifier.

17. The method of claim 14 , where the power supplied to the one or more light emitting devices is adjusted via a variable resistor.

18. The method of claim 14 , where the temperature is sensed via a thermistor, and where the thermistor is in a feedback path of an amplifier that amplifies the voltage.

19. The method of claim 14 , further comprising adjusting the voltage based on a desired irradiance output of the one or more light emitting devices.

20. The method of claim 14 , where the power is adjusted to provide a substantially constant irradiance output from the one or more light emitting devices.