LXXXIV. A review of wavelength calibration methods for visible-range photoelectric spectrophotometers [part one]

1975 ◽  
Vol 52 (5) ◽  
pp. A281 ◽  
Author(s):  
David H. Alman ◽  
Fred W. Billmeyer
Keyword(s):  
Visible Range ◽  
Wavelength Calibration ◽  
Calibration Methods

Wavelength Calibration Methods for Low-Resolution Photodiode Array Spectrometers

1993 ◽  
Vol 47 (7) ◽  
pp. 1007-1014 ◽  
Author(s):  
J. Thomas Brownrigg
Keyword(s):  
Measurement Errors ◽  
Calibration Method ◽  
Spectral Lines ◽  
Low Resolution ◽  
Position Measurement ◽  
Wavelength Calibration ◽  
Regression Methods ◽  
Calibration Methods ◽  
Wavelength Pair ◽  
Pair Method

A wavelength calibration method for low-resolution diode array spectrometers is described. The method was developed for routine calibration of 0.1-meter-focal-distance spectrometers having 35- or 38-element silicon diode arrays, normally operated in the 340–700 nm spectral range. Each diode of the array is approximately 1 mm wide, giving an instrumental bandwidth of ∼10 nm per diode. The calibration method requires two well-separated monochromatic spectral lines, their central image locations on the array, and the grating groove frequency. This method is compared with nonlinear regression (least-squares) methods, with multiple calibration lines fitted to quadratic or cubic polynomials. The predictive accuracy of the wavelength-pair method compares favorably with the regression methods. A calibration accuracy of ∼±1 nm is expected for the instruments considered here. The method described could, in principle, be applied to instruments with higher resolution, such as those having self-scanned photodiode arrays with 25-μm or 50-μm-wide pixels. For such instruments, however, a large number of calibration lines should be resolved. In this case, the regression method, which averages diode position measurement errors, is probably more accurate. The wavelength-pair method is most useful for low-resolution instruments, for which regression methods may not be practical.

scholarly journals A New Method of Wavelength Calibration for LAMOST by Combining Short- and Long-Exposure Spectral Lines

2012 ◽  
Vol 29 (1) ◽  
pp. 66-71 ◽  
Author(s):  
G. H. Ye ◽  
J. Zhu ◽  
Z. F. Ye
Keyword(s):  
Spectral Lines ◽  
New Method ◽  
Short Exposure ◽  
Selected Lines ◽  
Wavelength Calibration ◽  
Calibration Methods

AbstractIn wavelength calibration using arc lines, the normal approach is to use the strongest unsaturated lines, leaving weak lines unused. A new method is proposed in this paper, which not only utilizes the strong spectral lines, but also makes most use of weak spectral lines. In order to validate the effectiveness of the method we propose, experiments are performed on simulated spectra. Firstly, two kinds of spectra are generated: one with a short exposure and another with a long exposure. Secondly, calibration lines are chosen from the short exposure and long exposure spectra separately according to some rules. Thirdly, the initial wavelength calibration is completed by using the selected short-exposure lines. Fourthly, the approximate centroids of the selected long-exposure lines are obtained by utilizing the result of the initial wavelength calibration. These are then adjusted iteratively to obtain the centroids. Finally, the selected lines from the short- and long-exposures are combined to obtain the final wavelength calibration. Compared with traditional calibration methods which only use short exposures and strong lines, the proposed method is shown to be more accurate.

scholarly journals Comparison and analysis of wavelength calibration methods for prism – Grating imaging spectrometer

2019 ◽  
Vol 12 ◽  
pp. 143-146
Author(s):  
Ci Sun ◽  
Mingjia Wang ◽  
Jicheng Cui ◽  
Xuefeng Yao ◽  
Jianjun Chen
Keyword(s):  
Imaging Spectrometer ◽  
Wavelength Calibration ◽  
Calibration Methods ◽  
Comparison And Analysis

In-situ UV-Visible spectrometry as an alternative to determine solute concentrations at high temporal frequency in organic-rich stream waters

2021 ◽  
Author(s):  
Juan Pesántez ◽  
Christian Birkel ◽  
Giovanny Mosquera ◽  
Pablo Peña ◽  
Viviana Arizaga ◽  
...  
Keyword(s):  
Stream Water ◽  
Temporal Frequency ◽  
Calibration Method ◽  
In Situ Monitoring ◽  
Visible Range ◽  
High Temporal Frequency ◽  
Calibration Methods ◽  
Uv Visible ◽  
Visible Spectrometry

<p>In-situ monitoring of the temporal variation of solutes’ (nutrients and metals) concentrations as tracers can enhance knowledge of the hydrological and biogeochemical behavior of catchments. UV-Visible spectrometry represents a relatively inexpensive and easily used tool to explore how those concentrations vary in time at high temporal frequency. However, it is not yet clear which are the best calibration methods and which solutes can be modeled with this approach. In this investigation we explored the relationship between solutes’ concentrations and wavelength absorbance in the UV-Visible range to find the best calibration method and to identify solutes that could be effectively predicted. To this end, we installed a UV–Visible spectrometer probe in a high-altitude and organic-rich tropical Andean (Páramo) stream to record the wavelength absorbance at a 5-min temporal resolution from December 2017 to March 2019. Simultaneously, we sampled stream water at 4-hour frequency for subsequent determination of solutes via ICP-MS in the laboratory. Our results show that multivariate statistical methods outperformed simpler calibration strategies to model the solutes’ concentrations that could be effectively predicted using calibration and validation datasets. Eleven out of 21 evaluated solutes (Al, DOC, Ca, Cu, K, Mg, N, Na, Rb, Si and Sr) were successfully calibrated (NSE > 0.50). This finding suggests the possibility of calibrating solutes (i.e., metals) that had not previously been calibrated through UV-Visible spectrometry in the field. Interestingly, the calibration was feasible for all solutes that presented a statistically significant correlation with dissolved organic carbon. The findings of this research provide insights into the value of in-situ operation of spectrometers to monitor water quality in organic-rich streams (e.g., peatlands). This research contributes to our understanding of aquatic ecosystems alongside assessing catchment hydrological functioning and also can enhance the protection of human water supplies.</p>

Structural aspects of silicon diffusion in quaternary III-V thin-film semiconductors

1991 ◽  
Vol 49 ◽  
pp. 850-851
Author(s):  
F. A. Ponce ◽  
R. L. Thornton ◽  
G. B. Anderson
Keyword(s):  
Semiconductor Lasers ◽  
Wide Bandgap ◽  
Semiconductor Diode ◽  
Visible Range ◽  
P System ◽  
Misfit Dislocations ◽  
Lattice Match ◽  
Semiconductor Diode Laser ◽  
Thin Film Semiconductors ◽  
Silicon Diffusion

The InGaAlP quaternary system allows the production of semiconductor lasers emitting light in the visible range of the spectrum. Recent advances in the visible semiconductor diode laser art have established the viability of diode structures with emission wavelengths comparable to the He-Ne gas laser. There has been much interest in the growth of wide bandgap quaternary thin films on GaAs, a substrate most commonly used in optoelectronic applications. There is particular interest in compositions which are lattice matched to GaAs, thus avoiding misfit dislocations which can be detrimental to the lifetime of these materials. As observed in Figure 1, the (AlxGa1-x)0.5In0.5P system has a very close lattice match to GaAs and is favored for these applications.In this work, we have studied the effect of silicon diffusion in GaAs/InGaAlP structures. Silicon diffusion in III-V semiconductor alloys has been found to have an disordering effect which is associated with removal of fine structures introduced during growth. Due to the variety of species available for interdiffusion, the disordering effect of silicon can have severe consequences on the lattice match at GaAs/InGaAlP interfaces.

Formation of Luminescent Si Nanocrystals by High-Temperature Annealing of Ion-Beam-Sputtered Si/SiO2 Multilayers

2003 ◽  
Vol 775 ◽  
Author(s):  
Suk-Ho Choi ◽  
Jun Sung Bae ◽  
Kyung Jung Kim ◽  
Dae Won Moon
Keyword(s):  
Quantum Confinement ◽  
Radiative Recombination ◽  
Ion Beam ◽  
Quantum Confinement Effect ◽  
Visible Range ◽  
Ion Beam Sputtering ◽  
Transmission Electron ◽  
Si Nanocrystals ◽  
Beam Sputtering ◽  
Microscopy Images

AbstractSi/SiO2 multilayers (MLs) have been prepared under different deposition temperatures (TS) by ion beam sputtering. The annealing at 1200°C leads to the formation of Si nanocrystals in the Si layer of MLs. The high resolution transmission electron microscopy images clearly demonstrate the existence of Si nanocrystals, which exhibit photoluminescence (PL) in the visible range when TS is ≥ 300°C. This is attributed to well-separation of nanocrystals in the higher-TS samples, which is thought to be a major cause for reducing non-radiative recombination in the interface between Si nanocrystal and surface oxide. The visible PL spectra are enhanced in its intensity and are shifted to higher energy by increasing TS. These PL behaviours are consistent with the quantum confinement effect of Si nanocrystals.

Estimation of precipitation intensity due to image processing from the camera of the visible range

2018 ◽  
Vol 1 (3) ◽  
pp. 282-296
Author(s):  
V. N. Garmash ◽  
◽  
D. M. Korobochkin ◽  
S. A. Matveev ◽  
Y. V. Petrov ◽  
...  
Keyword(s):  
Image Processing ◽  
Precipitation Intensity ◽  
Visible Range
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