Ariel is a F3, astigmatism corrected, compact, fiberoptics spectrometer for industrial and R&D desktop applications. It uses unfolded Czerny-Turner system with 80mm optical bench, torroid mirror for astigmatism correction, SMA 905 fiberoptics input, Gigabit LAN and USB 2 connections and extensive auxilary port functions for communication with other devices. It is a rugged spectrometer using fixed optical bench without moving or adjusting parts.
Ariel spectrometer has low aberration design for the full spectrum that results in clean symmetrical peaks. Improved sensitivity at short and near-infrared wavelengths. All this coupled with fast integration time, onboard signal conditioning and LAN connectivity make Ariel spectrometer well suited for industrial and R&D applications.
ARIEL VIS: BASIC SPECIFICATION
Wavelength range, nm
Wavelength resolution (with 20µm slit)
Minimum integration time
Onboard data conditioning
Input fiber connector
Minimum integration time
Imaging (detector) plane of spectrometer with and without astignatism correction. A. Ariel spectrometer B. Same design w/o astigmatism correction. C. Design with 600 g/mm (typical for small spectrometers) w/o astigmatism correction
Spherical mirrors spectrometers can have significant astigmatism that is not corrected by Czerny-Turner design. Astigmatism means that a point at the entrance slit becomes a line at the imaging plane (on the detector). This results in the loss of light and increased scattering potential. Essentially, in case of oblique incidence, spherical mirror has different focus in sagittal and tangential planes. Astigmatism can be corrected using a cylindrical lens or torroid mirror. Torroid mirror is a cleaner but more expensive solution. High dispersion diffraction gratings (> 600g/mm) cause higher astigmatism that is more difficult to correct.
CMOS detector response is fairly linear at the low signals (<50% of dynamic range). But becomes non-linear at higher signals. The non-linearity is caused by the source- follower and charge to voltage converting capacitor. Hence, nonlinearity is slightly different from pixel to pixel. It is accurately corrected by factory calibration
Dark signal depends on integration time and temperature. Temperature dependence is relatively weak – dark signal decrease ~ 100 counts for 5 deg. increase in temperature. Temperature stabilizes after 40 min of operation. For an active CMOS detector, each pixel has a bit different dark current with a different rate of change. Careful factory calibration removes dark current.