Spectrometer with operator assistance for measurement optimization
The present disclosure relates to assistive mechanisms and methods that aid an operator of a spectrometer to make spectral measurements of a sample, the measurements having a desired quality. The method enables quality spectral measurements quickly and simply, without a prior understanding of a sample's spectrum or of the details as to how the spectrum is measured. Data quality is improved, and the time required to collect the data is reduced. While a specific example of sample optic focus is disclosed in detail, the optimization of numerous other parameters is possible.
1. A method of assisting an operator of a spectrometer to enhance the quality of a spectral measurement of a sample, the method comprising:
providing a spectrometer including a probe and a detector having a dynamic range, wherein the spectrometer is controlled by a processor in communication with a display device;
defining a regular update interval;
performing a series of automatic, individual spectral measurements of a sample during the update interval;
at the end of the update interval, calculating and displaying via the display device a measurement quality metric (MQM) based upon a combined spectral measurement of the sample taken during update interval using the processor;
providing information to the operator enabling the operator to optimize the MQM; and
repeating the series of individual spectral measurements, calculating and displaying the MQM, and providing information to the operator until a desired quality of the combined spectral measurement of the sample is achieved.
2. The method of claim 1 , wherein the information provided to the operator includes information advising the operator to position the probe and/or the sample to optimize the MQM.
3. The method of claim 1 , wherein optimizing the MQM includes minimizing, maximizing or approaching a desired value.
4. The method of claim 1 , the method further comprising dynamically adjusting the length and number of individual measurements in the update interval to stay within the dynamic range of the detector.
5. The method of claim 1 , the method further comprising aggregating the individual measurements taken during an update interval into the combined spectral measurement for that update interval.
6. The method of claim 1 , wherein the update interval is approximately one second.
7. The method of claim 1 , wherein the MQM is a function of time.
8. The method of claim 1 , wherein the MQM is a spectral intensity per unit time.
9. The method of claim 1 , wherein the MQM is a detector saturation per unit time.
10. The method of claim 1 , wherein the MQM is a signal-to-noise ratio at a fixed acquisition length.
11. The method of claim 1 , wherein the MQM is a residual sum of squares of the measured spectrum versus a known reference.
12. The method of claim 1 , wherein the MQM is a repeatability of a sample property of interest as calculated using an analytical model.
13. The method of claim 12 , wherein the sample property of interest is melt index.
14. The method of claim 1 , wherein the MQM and the information provided to the operator are used to optimize one or more of the following: detector gain, detector temperature, spectrograph etendue, spectrograph dispersion, spectrograph slit width, numerical aperture of the probe, laser wavelength, and band position relative to a detector matrix of the detector.
15. The method of claim 1 , wherein the information provided to the operator is visual, auditory or haptic.
16. The method of claim 15 , wherein the visual information provided to the operator is graphical or numerical.
17. The method of claim 15 , wherein the auditory information provided to the operator is a modulated tone pattern or an audio frequency.
18. The method of claim 15 , wherein the haptic information provided to the operator is a modulated vibrational pattern or a vibrational frequency.
19. A spectroscopic system for enhancing the quality of a spectral measurement of a sample, the spectroscopic system comprising:
a spectrometer having a detector in optical communication with a probe having a sample optic, wherein the spectrometer is adapted to measure signals from a sample;
a display device; and
a processor configured to control the spectrometer and the display device and to calculate a measurement quality metric (MQM), the processor further configured to develop a spectrum from the measured signals, to display the spectrum on the display device, to provide information to an operator of the spectrometer, enabling the operator to optimize the MQM until a desired quality of the combined spectral measurement of the sample is achieved.
20. The spectroscopic system of claim 19 , wherein the MQM is one of the following: a function of time; a spectral intensity per unit time; a detector saturation per unit time; a signal-to-noise ratio at a fixed acquisition length; a residual sum of squares of the measured spectrum versus a known reference; and a sample property of interest as calculated using an analytical model.