BTS2048-VL-TEC-WP

BTS2048-VL-TEC-WP BiTec sensor spectroradiometer for high-quality outdoor VIS measurements

The BTS2048-VL-TEC-WP is a high-quality spectralradiometer whose compact design and elaborate optical, electronic and mechanical interfaces make it ideal for high precision outdoor VIS measurements. Due to its spectrometer design and optional stray light reduction by the well know Zong or Nevas matrix methods it is able to measure solar radiation with a good straylight reduction performance. With the included S-BTS2048 application software precise measurements and data analysis can be intuitive performed. In addition for the UV spectral range with the complementary BTS2048-UV-S-WP a high resolution and even better device in terms of stray light reduction is available.

BiTec sensor for high-end light measurement 

One of the outstanding features of this exceptional spectroradiometer is its BiTec sensor. This combines the special properties of a photodiode with those of a back-thinned CCD diode array. Through bilateral correction of measurement signals from both sensors, the BiTec sensor ensures precise radiometric and spectral-radiometric measurement values over a large dynamic range (see technical article BiTec Sensor).

Spectrometer based on a high-quality back-thinned CCD detector 

The spectrometer unit is based on a diode array with a utilizable spectral responsivity range between 190 nm and 430 nm. It has a 0.7 nm optical bandwidth and a pixel resolution of 0.13 nm/pixel. Due to the back-thinned technology, this CCD chip is substantially more sensitive as compared to conventional front-illuminated CCD chips. Furthermore the CCD is one stage cooled (1TEC) to reduce the dark current and increased thereby the SNR.

Precise spectral radiometry (high dynamic and low straylight)

To facilitate optimum use of the CCD sensor‘s dynamic range and to overcome the problems of most array spectoradiometers in the UV range, the option to characterize and apply the Zong or Nevas straylight reduction methods is possible. For a high dynamic range a remote controlled filter wheel (Open, Closed, OD1 and OD2) is located in the optical beam path, this additional to the high dynamic of the integration times (2 µs to 60 s).

Accuracy for spectral AOD (Aerosol Optical Depth)

The BTS2048-VL-TEC-WP showed its high accuracy in a peer-reviewed paper in terms of high accuarcy spectral AOD measurements traceable calibrated.

WP means weather proofed

The housing of the BTS2048-VL-TEC-WP is designed for outdoor measurements. The cooled backthinned CCD and the spectrometer unit are temperature controlled in a second housing. In this housing humidity is removed by a exchangeable cartridge. To avoid dust, rain or snow on the entrance optics the quartz dome is blow-dried by warm air.

Diffuser window directly connected instead of light guide 

As for the input optics, the BTS2048-VL-TEC-WP has an incorporated diffuser window with a cosine corrected field of view. The fact that a light guide has not been used improves sensitivity and calibration stability which is an large advantage for outdoor use. Especially in terms of size of the device. The f2 adjustment of the cosine corrected field of view to less than 3% makes it possible to use the BTS2048-VL-TEC-WP for direct measurement in absolute radiometric measurands

• Irradiance (W/m²)
• Spectral irradiance (W/(m² nm))

State of the art interface

The BTS2048-VL-TEC-WP is controlled via a USB 2.0 or Ethernet interface. With regards to the communication speed and cable length the Ethernet port is superior to the USB2.0 interface. Furthermore, the data preparation occurs in the BTS2048-VL-TEC-WP to optimize the data-transfer speed. For this purpose, an independent, high-performance microprocessor is incorporated. Data and power interface are of course weatherproof designed as well.

User software with flexible desktop structure 

Among the BTS2048-VL-TEC-WP delivery contents is the S-BTS2048 user software. One of the characteristic features it has to offer is the flexible desktop that can be individually configured by the user. This entails a potpourri from which the user can choose graphical and numerical display windows:

• Freely definable numerical displays in decimal or scientific representation. Zoom function.
• Numerical display fields for radiometric, spectral and other measurands.
• Measurement protocol of the selected measurement parameters.
• Spectrum. Zoom function.
• Data logger. Zoom function.
• etc.

Traceable calibration 

Calibration of the BTS2048-VL-TEC-WP, including its accessories, is performed by Gigahertz-Optik ISO/IEC 17025 calibration laboratory for optical measurands with reference to national and international calibration standards. Due to the small dimensions of the device it can be shipped easily for re-calibration purposes.

Scientific Measurement Campaign

The BTS2048-VL-TEC-WP has took part in an scientific intercomparison, to prove the quality of the measurement data in the scientific framework.