High speed spectrometer

1. A system for measuring quantum efficiency in a photovoltaic cell, the system comprising:

a photovoltaic cell;

a Fourier transform infrared spectrometer comprising at least a white light source and a secondary light source for illuminating the photovoltaic cell;

a photocurrent analyzer electrically connected to the photovoltaic cell by an electrical conductor and configured to receive a photocurrent corresponding to a wavelength range; and

a processor configured to analyze photocurrent in the wavelength range.

2. The system of claim 1 , wherein the wavelength range corresponds to a predetermined wavelength range of interest.

3. The system of claim 1 , wherein the processor is configured to perform a Fourier transform to obtain a current versus wavelength curve for a wavelength range of interest.

4. The system of claim 1 , wherein the photocurrent analyzer comprises an amplifier for amplifying the photocurrent.

5. The system of claim 1 , wherein the photocurrent analyzer comprises an analog-to-digital converter for converting the photocurrent to a digital signal.

6. The system of claim 1 , wherein the white light source comprises a tungsten quartz halogen bulb.

7. The system of claim 1 , wherein the secondary light source comprises a light emitting diode.

8. The system of claim 7 , wherein the light emitting diode comprises a blue light emitting diode.

9. The system of claim 1 , wherein the secondary light source is configured to emit light having a peak wavelength of about 405 nm.

10. The system of claim 1 , further comprising a tertiary light source.

11. The system of claim 10 , wherein the tertiary light source comprises a light emitting diode.

12. The system of claim 11 , wherein the light emitting diode comprises a blue light emitting diode.

13. The system of claim 10 , wherein the tertiary light source is configured to emit light having a peak wavelength of about 455 nm.

14. The system of claim 1 , wherein the system is capable of scanning a wavelength range from 400 nm to 900 nm in less than about 5.2 seconds.

15. The system of claim 14 , wherein the system is capable of scanning a wavelength range from 400 nm to 900 nm in less than about 2.6 seconds.

16. The system of claim 15 , wherein the system is capable of scanning a wavelength range from 400 nm to 900 nm in less than about 1.3 seconds.

17. The system of claim 1 , wherein the processor is configured to analyze photocurrent in the wavelength range using a predetermined data spacing of 15.428 cm−1 corresponding to an average wavelength resolution of 0.557 nm in a wavelength range from 400 nm to 900 nm.

18. The system of claim 17 , wherein acquiring photocurrent in the wavelength range from 400 nm to 900 nm takes less than about 5.2 seconds.

19. The system of claim 17 , wherein the performing comprises using a predetermined data spacing of 15.428 cm−1 corresponding to an average wavelength resolution of about 0.557 nm in a wavelength range from 400 nm to 900 nm.

20. The system of claim 1 , wherein the processor is configured to analyze photocurrent in the wavelength range using a predetermined data spacing less than 15.428 cm−1 corresponding to an average wavelength resolution better than 0.557 nm in a wavelength range from 400 nm to 900 nm.

21. The system of claim 1 , further comprising an external voltage bias source electrically connected to the photovoltaic cell and configured to bias the photovoltaic cell.

22. The system of claim 1 , further comprising an optical fiber configured to transmit light from the white light source and secondary light source to the high speed spectrometer.

23. The system as in claim 1 , further comprising an external light source for biasing the photocell.

24. The system as in claim 1 , wherein the light from the white light source and secondary light source are directed to the spectrometer by a fiber optic bundle.

25. The system as in claim 24 , wherein light existing the fiber optic bundle is columnated.

26. The system as in claim 1 , wherein light from the white light source and secondary light source in an optical path including mirrors and lenses.

27. The system as in claim 1 , wherein the white light source and secondary light source are independently controllable.

28. A method for testing quantum efficiency in a photovoltaic cell, the method comprising:

performing a Fourier transform on beams of light emitted from a white light source and a secondary light source;

directing the Fourier-transformed beams of light toward a photovoltaic cell to generate a photocurrent corresponding to a wavelength range;

conducting the photocurrent from the photovoltaic cell to an analog-to-digital converter to produce a digital signal corresponding to the wavelength range; and

performing a reverse Fourier transform on the digital signal to obtain the photocurrent versus wavelength curve in the entire wavelength range.

29. The method of claim 28 , wherein the directing comprises conducting the Fourier-transformed beams of light through an optical fiber.

30. The method of claim 28 , wherein the directing comprises redirecting the Fourier-transformed beams of light with a mirror.