We use Optical Character Recognition (OCR) during our scanning and processing workflow to make the content of each page searchable. You can view the automatically generated text below as well as copy and paste individual pieces of text to quote in your own work.
Text recognition is never 100% accurate. Many parts of the scanned page may not be reflected in the OCR text output, including: images, page layout, certain fonts or handwriting.
240
V. K. ZWORYKIN
September
pyramid, whose four sides act as first dynode for four electron multiplier structures. The output currents of the four multipliers pass through four deflecting coils, which serve to maintain the fixed star image centered on the pyramid, so that the sidereal image reproduced on a viewing tube screen appears stationary.
The above method requires the construction of a highly specialized complex electronic centering tube. The same end may, however, be accomplished with the aid of conventional television equipment in conjunction with suitable gating circuits. Figure 14 shows a block diagram of the circuit which may be employed for this purpose.
LIMITS OF SENSITIZED INTERVAL
VERTICAL PULSES
1
,
1
In _J______
T
! i
_
i
I
i
HORIZONT
AL
CORRECTING PULSE
i
1
I
1
1
..PRESCRIBED STAR POSITION IN SCANNING PATTERN
PRESCRIBED STAR POSITION IN SCANNING PATTERN
HORIZONTAL CORRECTING PULSE
Fig. 14. Electronic image stabilizer for sidereal images.
The sidereal image is projected by the telescope on the photosensitive surface of the pickup tube so that the fixed star serving as "guiding star" is centered on it. Apart from the amplifiers and the television receiver on which the sidereal image is reproduced, centering circuits are provided whose purpose it is to maintain the scanning pattern centered on the guiding star image, independent of atmospheric fluctuations and minor clock errors. Here the output signal of the pickup tube is applied to two gating circuits which are sensitized over a series of time intervals covering a region of a few line widths about the prescribed position of the image of the guiding star in the scanning pattern. If the star image moves slightly in the course of