3
Device description
Light attenuation meter FOTOMETER 2008 consists of modulated light source, lock-
in type light detector and control unit. Device measures intensity of light traveling from the
light source to the light detector. It makes the device suitable for measurement changes of
attenuation of light in the area between the light source and the light detector. Due to
synchronization between light source modulation and the light detector the device is, to some
extent, immune to ambient light and could be operated on normal day light conditions.
The readout of intensity value is in linear arbitrary units (AU) and is not directly
related to any engineering units. The device is intended only for measurement of relative
changes in light intensity.
Device has four decadic ranges and could be operated in two different modes. In
manual mode
the ranges must be switched manually by user. In
automatic mode
the device
itself changes mode when intensity readout goes out of actual range.
The light detector is equipped with two input filters.
Fast filter
provides quick
response but slightly higher noise and is intended for measurement of unstable, changing light
intensity. For measurement in stable, balanced conditions might be done using
slow filter
which reduces noise but has very long settling time (up to one minute).
Safety rules
The control unit is powered by 230V AC which might be dangerous to life. Never remove the
cover of control unit when the mains electricity is connected. Mains plug MUST be always
removed before unscrewing the cover. Any service must be provided by a qualified electrician
only.
Device may be operated only in room environment between 15 and 40 C with non condensing
humidity. When moving device from cold environment to room temperature always allow the
device temperature to accommodate to room environment to avoid moisture to condensate on
the device before switching the device on.
Setting up the device
Mount control device to its place, preferably a 19 inch rack case. Connect 15 pin cable
between the control unit and the detector and 25 pin cable between the control unit and the
light source. Double check that cables are connected properly according to labels on control
unit. Connect mains electricity and switch the device on.
The light source and light detector must be mounted in such position that light source
outlet is facing the light detector inlet directly. The light beam must go through the area where
the light attenuation should be measured. Make sure that axes of light source outlet and light
detector inlet are perfectly parallel. Using small piece of paper make sure that the light beam
is aimed directly to the center of light detector inlet.
