Abstract: A method for measuring cloud height, in which a train of light pulses is sent from a transmitter into the investigated air space. From each of a number of different height intervals, signals reflected towards a receiver are integrated and measured. The time, the pulse number, the pulse frequency and/or the pulse energy for each height interval are controlled with respect to the energy reflected and received in the receiver from underlying measuring intervals, thus obtaining compensation for losses in the energy of the light pulses in reaching the respective level.

Abstract: In a cloud height measuring device, the attenuation caused by deposits on the output and/or receiver windows of the device (e.g. by rain and/or dirt) are compensated for by measuring the degree of reflection of light from the window(s) when illuminated by light pulses. By means of a special measuring sequence in a processor unit included in the cloud height measuring device, light pulses separate from those used for the cloud height measurement itself, can be employed to assess the extent of the fouling. The measurement energy can then be controlled during the cloud height measurement proper, so that the total attenuation, caused by rain and dirt on the windows, is properly compensated for.

Abstract: An apparatus for contact-free sensing of a moving coherent mass of material, for example a stream of molten glass, comprises first sensing means for producing first output signals for determining the speed of advance of the material past the sensing apparatus and second sensing means for producing a second output signal related to a dimension, e.g. the diameter, of the material transverse to its direction of advance. The sensing apparatus further includes optical means comprising a common objective lens for supplying radiation focussed from the material being sensed to both said first and second sensing means.

Abstract: The invention relates to a measuring signal transmission device for transmitting signals between a rotating portion and a rotationally stationary portion, for example in a large electrical machine. The rotationally stationary portion is journalled to the rotating portion in such a way as to accompany the latter portion in its axial and radial movements, and light is arranged to be transmitted in both directions between the rotating portion and the rotationally stationary portion by light conductors at the center axis of rotation and/or at specified radii and at least one light-conducting fiber is located in the rotating portion and at least one light-conducting fiber is located in the rotationally stationary portion, whereby the light signal transmission is arranged to take place between fibers located at the same radii in both portions.

Abstract: The invention relates to a fiber optic temperature-measuring apparatus, based on the photo-luminescence of a solid material which is subjected to the temperature to be measured. The apparatus is characterized in that several sensors made of such a temperature-sensitive luminescent material are located in various places, each one being connected to a light-emitting diode via at least one optical fiber. Luminescent light emitted from each sensor is arranged to be supplied, via at least one separate optical fiber, possibly partially via the above-mentioned fiber and a fiber branch, to a receiver unit, common to all the sensors, the excitation light signal from each light-emitting diode being time-division multiplexed.

Abstract: In visibility measuring apparatus, a transmitter including at least one transmitter optic for emitting light signals and at least one receiver including at least one receiver optic for receiving the emitted light signals are positioned in a measuring base defined by the distance between the at least one transmitter optic and the at least one receiver optic. A central unit controls the light emitting signals and processes the light signals received from the at least one receiver optic. Signal light conductors interconnect at least some of the transmitter and transmitter optics, the central unit and the transmitter and the receiver optics and the central unit. In a modified embodiment each measuring base may include a separate transmitter optic and a separate receiver optic. Additionally, calibration signals may be transmitted from the central unit to each receiver optic by additional light conductors with separate light conductors for returning a reference signal from each receiver optic to the central unit.