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metcon meteorologieconsultgmbh,

Instruments for Atmospheric Research

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ACTINIC FLUX SPECTRAL RADIOMETERS Ultra-fast CCD-Detector Spectrometer, UVB enhanced • Cooled CCD, 512 pixel * 64 pixel, line binned • Spectral range: 280 nm – ca. 650 nm, spectral resolution < 1.8 nm (FWHM) • Receptor-Optics: 2-pi-actinic, irradiance, direct sun • Installed in an air- and water-tight housing • Aircraft – suitable

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FAST MONOLITHIC SINGLE MONOCHROMATOR - SPECTRAL RADIOMETER

WITH CCD - DETECTOR FOR ACTINIC FLUX This spectrometer is capable of measuring actinic flux, photolysis rates and direct sun from spectrally resolved data beginning at low UV-wavelengths. Therefore, it is not necessary to correct the measurements in the UVB range for varying total ozone columns. In the case of J(O1D) photolysis, the device is suitable even at low solar elevations. It is based on a monolithic mono-chromator without moving parts. Made from ce-ramics/glass, the monochromator has negligible sensitivity to temperature changes, resulting in very stable wavelength settings. The spectrometer has an extremely fast response time. It uses a 512 pixel CCD detector with a spa-tial resolution of ca 0.85 nm (pixel-distance) and spectral resolution (FWHM) of <1.8 nm. The spec-trometer can determine ozone photolysis rates with a typical time resolution as low as 1s, de-pending on the solar elevation. J(NO2) is meas-ured at frequencies up to > 5 Hz. This makes the spectrometer useful for aircraft applications. The spectrometer is housed in an air and water tight aluminum case. The system comes ready for field use, as do all our instruments.

All spectrographs are delivered with a Windows Notebook and dedicated software package. The software supplied with the spectrometer records and stores the spectral raw data, and evaluates the photolysis rates for, e.g., j(O1D), j(CHO), j(NO2), j(HONO), and j(NO3) in real-time. The spectrometer is controlled by a PC via an Ethernet Interface. Data-averaging intervals can be selected by the user in the range between a few seconds and 30 minutes. For aircraft installation, the receptor optics can be mounted apart from the spectrometer, connected by an optical fiber. The system is absolutely calibrated with a NIST/PTB traceable 1000 Watt FEL-lamp. Atmospheric inter-comparison and a multi-day test in the atmosphere prior to delivery is performed and documented. The signal-stability of the absolutely calibrated instru-ments in the sealed housings is excellent. The in-struments are widely used in atmospheric research on ground-based stations and in research aircraft. A calibration setup consisting of an optical bench, a highly stable 1000 Watt current-controlled power supply with precision voltmeter and shunt for 100W FEL-lamps can be supplied.

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SPECIFICATIONS

RECEPTOR OPTICS

ISOTROPIC DIFFUSER FOR ACTINIC FLUX MEASUREMENTS

Quartz scattering dome with a nearly uniform response over 2p sr, hermetically sealed (tested to 0.5 bar).

SPECTROMETER TYPE Adapted monolithic single monochromator with fixed grating

OPTICAL COUPLING Quartz fiber, round to slit converter WAVELENGTH RANGE 280 - 650 nm (512 pixel)

SPECTRAL RESOLUTION (FWHM) ca. 1.8 nm nominal resolution at 300 nm TEMPERATURE SENSITIVITY < 0.05 nm/K STRAY LIGHT SUPPRESSION Compensation using signal between 280 and 290 nm

DETECTOR Ultra-fast cooled back thinned CCD MEASUREMENT TIME FOR PHOTOLYSIS RATES

Photolysis rate for jO1D: < 200 ms

ELECTRONICS

RESOLUTION / PRECISION 14-bit, 64 000 counts max RESOLUTION OF J(NO2) MEASUREMENTS Better than 0.3 % for sun elevation at 25° for jNO2

REPRODUCIBILITY OF SUCCESSIVE SCANS ca. +/- 3 counts per pixel at 25°C POWER 12/24 VDC / 115 / 230 VAC

DATA ACQUSITION AND CONTROL

PHOTOLYSIS RATE: SIGNAL-OPTIMISATION Molecule optimized integration time DATA-ACQUISITION / INSTRUMENT CONTROL Notebook, Interface Electronics: ETHERNET

DATA STORAGE

Data stored as ASCII files (date, time, spectral raw data), photolysis rates of O3, CH3CHO, HCHO, NO2 etc. in real-time

DATA EVALUATION

Software package for real-time evaluation of calibrated spectra and photolysis rates.

MECHANICAL DETAILS OF DEVICE

HOUSING Aluminum, water- and air -tight, tested to 0.5 bar DIMENSIONS ca. 300 * 200 * 30 mm3

WEIGHT < 5 kg DISTANCE FROM COMPUTER ETHERNET Cable delivered: 15 m

HUMIDITY CONTROL / REMOVAL Humidity sensor installed inside the housing, Drying agent installed outside the housing.

OPTIONS FOR LIGHT COUPLING UV/VIS or VIS/NIR optical fiber up to 20 m as option

AIRCRAFT OPTIONS 19"-Rack-Mount or other adapted housing, shock mounted, quartz domes with thick walls coupled to spectrometer via an optical fiber

OPTIONS FOR CALIBRATION Highly stable power supply, current controlled 1000W

FEL halogen lamp, shunt, DVM, optical bench

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Diode Array Spectrometer with Actinic Optics

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CCD-Detector-Spectrometer, optical receptor and spectrometer

are connected via an optical fiber.

CCD-Detector-Spectrometer combined with the electronics for the

Peltier cooling of the detector