Apparatus, system and method for scanning monochromator and diode array spectrometer instrumentation
A system and method for determining bias in a spectrometer is described. One embodiment includes a method for determining bias in a spectrometer system, the method comprising over-scanning a grating in a near-zero-response wavelength range; and determining a bias based on the over-scanning. This methodology allows for over-scanning a grating in a near-zero-response wavelength range as a substitute for using shutters or other mechanisms to block light from entering a detector in the system.
1. A method for determining bias in a spectrometer system, the method comprising:
over-scanning a grating in a near-zero-response wavelength range, wherein the near-zero-response wavelength range is a wavelength range in a filter-absorbing wavelength region of a filter in the optical path of a detector used to perform the over-scanning; and
determining a bias based on the over-scanning.
2. The method of claim 1 , wherein the near-zero-response wavelength range is a wavelength range within which the response of a detector used to perform the over-scanning is equal to, or less than, 10 −5 times the peak response of the detector.
3. The method of claim 1 , wherein the near-zero-response wavelength range is a wavelength range outside a detection range of a detector used to perform the over-scanning.
4. The method of claim 1 , wherein the filter-absorbing wavelength region is a region wherein 0.02% or less of light is transmitted by the filter.
5. The method of claim 1 , wherein the filter-absorbing wavelength region is a region wherein 0.01% or less of light is transmitted by the filter.
6. The method of claim 1 , wherein the over-scanning occurs at the beginning of the detector's nominal wavelength range and the selectively absorbing filter includes a long-pass filter designed to absorb at wavelengths at the beginning of the detector's nominal wavelength range.
7. The method of claim 1 , wherein the over-scanning occurs at the end of the system's nominal wavelength range and the selectively absorbing filter includes a short-pass filter designed to absorb at wavelengths at the end of the system's nominal wavelength range.
8. A method for spectroscopic measurements, the method comprising:
making a spectroscopic measurement with a spectrometer, wherein the spectroscopic measurement is made within a measurement range for the spectrometer;
performing an over-scan in a near-zero-response wavelength range, wherein the near-zero-response wavelength range is a wavelength range in a filter-absorbing wavelength region of a filter in the optical path of a detector used to perform the over-scan; and
determining a bias based on the over-scan.
9. The method of claim 8 , wherein the near-zero-response wavelength range is a wavelength range within which the response of a detector used to perform the over-scan is equal to, or less than, 10 −4 times the peak response of the detector.
10. The method of claim 8 , wherein the near-zero-response wavelength range is a wavelength range outside a detection range of a detector used to perform the over-scan.
11. The method of claim 8 , wherein the filter-absorbing wavelength region is a region wherein 0.02% or less of light is transmitted by the filter.
12. The method of claim 8 , wherein the over-scanning occurs at the beginning of the detector's nominal wavelength range and the selectively absorbing filter includes a long-pass filter designed to absorb at wavelengths at the beginning of the detector's nominal wavelength range.
13. The method of claim 8 , wherein the over-scanning occurs at (a) the end of the system's nominal wavelength range and the selectively absorbing filter includes a short-pass filter designed to absorb at wavelengths at the end of the system's nominal wavelength range; and (b) the beginning of the detector's nominal wavelength range and the selectively absorbing filter includes a long-pass filter designed to absorb at wavelengths at the beginning of the detector's nominal wavelength range.
14. A method for determining bias in a spectrometer system, the method comprising:
providing a detector;
positioning a grating such that a wavelength selected by the grating is in a near-zero-response wavelength range, wherein the near-zero-response wavelength range is a wavelength range in a filter-absorbing wavelength region of a filter in the optical path of a detector used to perform the over-scan; and
determining a bias by measuring the detector's response at the wavelength.
15. The method of claim 14 , wherein the wavelength is outside a detection range of the detector.
16. The method of claim 14 , further comprising:
changing the position of the grating such that the detector measures a bias-sample range, wherein the bias-sample range is in the near-zero-response wavelength range; and
determining the bias based on an average of the measurements in the bias-sample range.
17. The method of claim 14 , wherein the filter-absorbing wavelength region is a region wherein 0.02% or less of light is transmitted by the filter.