The Russian designation for the device (at least the transliterated designation) is BCK-4. Here's the writeup on it from the Soyuz Crew Operations Manual (reference at bottom of answer).
BCK-4 COSMONAUT VISUAL SYSTEM
The BCK-4 Cosmonaut Visual
System is designed for the spacecraft attitude monitoring in orbital
flight phase, docking procedure monitoring and space object visual
The BCK-4 has external and internal
(cabin) parts which are installed on the window located in the CA o
Module at the spacecraft “-Y” axis. The instrument visor axis is 6
inclined relative “-Y” axis. The external part consists of the central
viewing tube and the peripheral tubing unit . The instrument line of
sight can only be in two fixed positions: 0 degrees (“Ориент”)
(Attitude Monitor) and 84 degrees (“Причал”) (Berthing). The position
is changed by turning the mirror unit in the central tube head using
an electric motor. The cabin part includes the instrument body with
elements of the two optical systems and the control knob panel (Fig.
The “Центр. Светофильтр” (Central Light Filter) knob is used to insert
a neutral light filter into the central optical system field of view.The
“Экран” (Screen) knob is used for focus adjustment by moving the
screen along the visor axis. Rotating the “Светофильтр периф ep”
(Peripheral Light Filter) knob a dark light filter can be introduced
into any of the eight peripheral tubes. The “Шторка” (Shutter) knob
purpose is to shut off the field of view of all the eight peripheral
Crew operations with the BCK-4
Throughout all the orbital flight the
crew uses the BCK-4 as the principal instrument for monitoring the
spacecraft attitude and attitude maneuvers for which the visor axis is
set into the “Ориент” position by КСП-Л В-18 command.
attitude - orbital Earth coordinate system (OCK) with preset heading
angle is considered established when the reference object (Earth)
apparent run direction in the central system field of view is parallel to the heading indicator stroke rotated at the preset angle. And
the Earth horizon in the screen peripheral zone must be parallel to
the corresponding strokes or coincide with them.
the visor line is set in the “Причал” position by the КСП-Л В-17
command. At the range of 2 km the crew selects the screen according to
the illumination conditions. In the shadow the lens screen is used and
in the sunlight the matte screen is preferable. At this range it is
possible to estimate the range using the screen grid. Charts and
tables for range determination by the target angular size are included
into the FDF ((“Nominal Modes”).
ВНУК-К NIGHT TIME CONTROL VISOR
The ВНУК-К Night Visor is used for visual monitoring
the spacecraft heading attitude through the BCK-4 at the shadow part
of the orbit and for observing faintly illuminated object through the
The ВНУК-К сonsists of (Fig. 2):
collective, objective, electronic/optical converter ЭОП(brightness
converter) and biocular.
The Infrared rays are passing through the
collective (adapter of BCK-4 and ВНУК-К optical systems), then through
the objective and are focused at the ЭОП converter input plane. The
ЭОП converts the IR signal into video image which is viewed by the
cosmonaut via the biocular. The biocular and objective are fixed to
the ЭОП by screwed joints and the collective is connected to it by
means of special pin locks. For the spacecraft heading attitude
monitoring a rotatable grid is used. The ВНУК-К Visor principal
controls are located at the ЭОП converter:
- “Сеть” toggle switch - for power supply switching ON;
- “Яркость” knob - for brightness adjustment;
- Grid control knob. The Visor field of view can be closed by means of a shutter located in the collective, the shutter control knob having
only two positions: “Откр” (Open) “Закр” (Closed).
Crew Operation with ВНУК-К
ВНУК-К is used at the shadowed part of the
spacecraft orbit for monitoring orbital attitude system (ОСК) and for
the target acquisition and its attitude monitoring during approach and
docking in the shadow. When operated jointly with the ВСК-4 it is
necessary to: take the covers off, open the shutter, switch ON the
“Сeть” toggle switch at the ВНУК-К and using the “Яркость” knob adjust
the image brightness to optimal level. To monitor the spacecraft
heading attitude using the “Сетка” knob match the grid vertical
strokes with the terrain run direction and read the angle on the knob
scale. When the ВНУК-К is operated in autonomous mode it is necessary to
dismount he collective. Other operations are similar to those of the
joint mode with the ВСК-4. After every 5 hours of the ВНУК-К continuous operation an interval of 30 minutes is necessary.
Reference "Soyuz Crew Operations Manual (SoyCOM) (ROP-19) (Final) , Yu. A. Gagarin Cosmonaut's Training Center, NAS15-10110, 0004AE7a (ROP-19), April 1998" which is in English, although translated, it's an OK job.
You can find a copy at this page.