Nonlinearity characterization of array spectroradiometers for the solar UV measurements

Pulli, Tomi; Nevas, Saulius; Gawhary, Omar El; Berg, Steven van den; Askola, Janne; Kärhä, Petri; Manoocheri, Farshid; Ikonen, Erkki

doi:10.1364/ao.56.003077

Cited by 15 publications

(9 citation statements)

References 18 publications

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“…The linearity of the BTS2048-UV-S was tested using both the integration time and the irradiance variation methods (Pulli et al 2017). For the integration time method, the spectral irradiance of the incident radiation is kept constant while the instrument's integration time is varied over a wide range.…”

Section: Characterisationmentioning

confidence: 99%

Adaption of an array spectroradiometer for total ozone column retrieval using direct solar irradiance measurements in the UV spectral range

Zuber¹,

Sperfeld

Riechelmann

et al. 2018

Atmos. Meas. Tech.

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Abstract. A compact array spectroradiometer that enables precise and robust measurements of solar UV spectral direct irradiance is presented. We show that this instrument can retrieve total ozone column (TOC) accurately. The internal stray light, which is often the limiting factor for measurements in the UV spectral range and increases the uncertainty for TOC analysis, is physically reduced so that no other straylight reduction methods, such as mathematical corrections, are necessary. The instrument has been extensively characterised at the Physikalisch-Technische Bundesanstalt (PTB) in Germany. During an international total ozone measurement intercomparison at the Izaña Atmospheric Observatory in Tenerife, the high-quality applicability of the instrument was verified with measurements of the direct solar irradiance and subsequent TOC evaluations based on the spectral data measured between 12 and 30 September 2016. The results showed deviations of the TOC of less than 1.5 % from most other instruments in most situations and not exceeding 3 % from established TOC measurement systems such as Dobson or Brewer.

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Section: Characterisationmentioning

confidence: 99%

Adaption of an array spectroradiometer for total ozone column retrieval using direct solar irradiance measurements in the UV spectral range

Zuber¹,

Sperfeld

Riechelmann

et al. 2018

Atmos. Meas. Tech.

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“…The nonlinearity of an array spectroradiometer depends for instance on the used detector chip, the readout electronics (analog-to-digital converter (ADC)) and the remaining deviation after applying a correction based on a characterisation of the detector system (Pulli et al 2017). Since the electronics, detector chip and characterisation procedure are identical to the UV-BTS, Figure 1.…”

Section: Vis-btsmentioning

confidence: 99%

Global spectral irradiance array spectroradiometer validation according to WMO

Zuber¹,

Ribnitzky²,

Tobar

et al. 2018

Meas. Sci. Technol.

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Solar spectral irradiance measured by two recently developed array spectroradiometers (called UV-BTS and VIS-BTS) are compared to the results of a scanning double monochromator system which is certified as a travelling reference instrument by the Network for the detection of atmospheric composition change (NDACC) and fulfils the specifications of S-2 UV instruments of the world meteorological organization (WMO). The comparison took place between 15 and 18 May 2017 at the Institute of Meteorology and Climatology of the University of Hanover (IMuK) between 4:00 and 17:00UTC. The UV-BTS array spectroradiometer is equipped with special hardware to significantly reduce internal stray light which has been the limiting factor of many array spectroradiometers in the past. It covers a wavelength range of 200 nm-430 nm. The VIS-BTS covers a wider spectral range from 280 nm up to 1050 nm, and stray light reduction is achieved by mathematical methods. For the evaluation, wavelength integrated quantities and spectral global irradiance are compared. The deviation for UV index measured by the UV-BTS, is within ±1% for solar zenith angles (SZA) below 70° and increased to a maximum of ±3% for SZA between 70° and 85° when synchronisation between measurements was possible. The deviation of global spectral irradiance is smaller ±2.5% in the spectral range from 300 nm to 420 nm (evaluated for SZA < 70°). The VIS-BTS achieved the same deviation for blue light hazard as the UV-BTS for the UV index. The evaluations of global spectral irradiance data of the VIS-BTS show a deviation smaller than ±2% in the spectral range from 365 nm to 900 nm (evaluated for SZA < 70°). Below 365 nm, the deviation rises up to ±7% at 305 nm due to remaining stray light. The agreement within the limited time of the intercomparison is considered to be satisfactory for a number of applications and provides a good basis for further investigations.

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“…Experiments have indicated that the non-linearity at an intensity of about 50,000 (of a maximum of 65,535) counts is in the range of up to 1000 counts on the intensity scale, or up to 0.04 absorption units on the absorbance scale, using a Hamamatsu C10082CA mini-spectrometer [4]. Non-linearities in the light intensity response of CCD spectrometers greater than 10% were found in recent studies and the corresponding corrections resulted a non-linearity of less than 0.5% [5,6]; in one study a custom-designed spectrometer [5] was used and in the other an Avantes Avaspec-ULS2048L spectrometer and a StellarNet Blue-Wave spectrometer [6] were used. To the best of our knowledge, Ocean Optics Inc. is the only supplier that provides non-linearity correction software (OOINLCorrect, Ocean Optics Inc., Dunedin, FA, USA) for their CCD spectrometers, which provides linearities >99.8% [7].…”

Section: Introductionmentioning

confidence: 99%

Improving Optical Measurements: Non-Linearity Compensation of Compact Charge-Coupled Device (CCD) Spectrometers

Nehir

Frank

Aßmann

et al. 2019

Sensors

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Charge-coupled device (CCD) spectrometers are widely used as detectors in analytical laboratory instruments and as sensors for in situ optical measurements. However, as the applications become more complex, the physical and electronic limits of the CCD spectrometers may restrict their applicability. The errors due to dark currents, temperature variations, and blooming can be readily corrected. However, a correction for uncertainty of integration time and wavelength calibration is typically lacking in most devices, and detector non-linearity may distort the signal by up to 5% for some measurements. Here, we propose a simple correction method to compensate for non-linearity errors in optical measurements where compact CCD spectrometers are used. The results indicate that the error due to the non-linearity of a spectrometer can be reduced from several hundred counts to about 40 counts if the proposed correction function is applied.

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Nonlinearity characterization of array spectroradiometers for the solar UV measurements

Cited by 15 publications

References 18 publications

Adaption of an array spectroradiometer for total ozone column retrieval using direct solar irradiance measurements in the UV spectral range

Adaption of an array spectroradiometer for total ozone column retrieval using direct solar irradiance measurements in the UV spectral range

Global spectral irradiance array spectroradiometer validation according to WMO

Improving Optical Measurements: Non-Linearity Compensation of Compact Charge-Coupled Device (CCD) Spectrometers

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