Physics of auroral phenomena : proceedings of the 36th Annual seminar, Apatity, 26 February – 01 March, 2013 / [ed. board: A. G. Yahnin, A. A. Mochalov]. - Апатиты : Издательство Кольского научного центра РАН, 2013. - 215 с. : ил., табл.

В. V. Kozelov el al. SONY CCD ICX429ALL with EXview HAD microlens for enhanced near infrared light sensitivity. However in our case we need to decrease influence of the long-lived oxygen-atom states which gives the auroral red line 630 nm, therefore the cameras have been additionally equipped by blue-green glass filter. The relative responses for the camera sensor and for the glass filter given by manufactures are shown in Fig.l. The optical system includes also an input glass (visually transparent) of the thermal box where the camera is compiled. wave length, nm Fig. 1 Relative responses: 1 - SONY CCD ICX429ALL sensor (dotted line - extrapolation in region X<400 nm); 2 - glass filter C3C21; 3 - r(A), theoretical relative response of the optical system (renormalized multiplication of previous two curves); 4, 5, 6 - transmittance of the interference filters. Relative response of the optical system, т(Я), estimated by this available information is shown in the Fig.l by line 3. Three additional filters (‘Red’, ‘Green’ and ‘Blue’) with narrow bandwidths were used for the measurements, their responses are also plotted in Fig. 1. The camera calibrations were provided in optical room of Apatity department of Polar Geophysical Institute during 4 September 2012. The light from the LED- based light source SID 105 moving through collimator of ~ 1 m length and through additional interference filter results in a circular patch o f 1 0 pix radius in center of the camera frame. This patch was used as a calibration region and the average intensity over the region was calculated for each frame. The cameras were operated in Format-7 Mode-2 that gives 376x288 pixels frame. The measurements were repeated 10 times sequentially for 14 gain levels from 0 to 650 with the step 50. Temperature in the camera box was measured continuously and it was equal to 26±1°C. The light source was powered by new set of ЗхАА Alcaline batteries for each camera. It was founded that due to different time interval o f the measurements (~53 and ~37 minutes) the decrease of the battery voltage was decreased to 15% and 9% for the G1 and G2 cameras, correspondently. Unfortunately, the battery parameters were not measured directly during this session, therefore it was deduced from results of additional measurements described in next section: voltage V - 4.4±0.2 V and I 0bs=»380±20 mA. The “black” field CBF{x,y) was obtained when the light source was tuned off and the input window of the camera was closed. The average “black”(dark current) level in the calibration region, CBFix0,y0), was also calculated from the field for the set o f camera gain levels. It was founded that both cameras have individual inhomogeneity of the CCD matrix (‘hot pixels’) and bright top-left region due to heating of the CCD matrix by other camera components. To obtain the “white” field we used white paper mounted at the wall and illuminated by the low light source from distance ~ 5 m. To compensate angular inhomogeneity in this case we repeat the measurements with camera rotated at 180° and the results of the measurements was averaged. As a result we found that the matrix Q(xy) calculated by “black” and “white” fields is practically independent on gain (within <5%), but individual for each camera. The relative difference between the centrum of the Q(x,y) array and in the angles reaches -50% . 0 200 400 600 0 200 400 600 9 ° 'n gain Fig. 2 Average count rate (the light intensity) as a function of the camera gain: a - for camera G -l; b - for camera G-2. Lines 1, 2, and 3 were obtained in correspondent experiments, see Table 2. Line 4 is subtracted background. 152