Abstract: A first, upper slotted disk (10) and a second, lower slotted disk (20) are arranged as a gas inlet (11) in a gas-measuring device (1). The first, upper slotted disk (10) and the second, lower slotted disk (20) are connected to one another and to a sensor housing (2) via a spacer element (29). The arrangement of the slotted disks (10, 20) in relation to one another is selected to be such that reduced propagation of light of an infrared radiation source (43) through both slotted disks (10, 20) into the measuring environment is achieved.

Abstract: A first, upper slotted disk (10) and a second, lower slotted disk (20) are arranged as a gas inlet (11) in a gas-measuring device (1). The first, upper slotted disk (10) and the second, lower slotted disk (20) are connected to one another and to a sensor housing (2) via a spacer element (29). The arrangement of the slotted disks (10, 20) in relation to one another is selected to be such that reduced propagation of light of an infrared radiation source (43) through both slotted disks (10, 20) into the measuring environment is achieved.

Abstract: A ceilometer operating according to a gating method integrates output signals from a light receiver. The output signals are passed by analog gating means during consecutive time slots following each other at the transmitter frequency and being phase shifted relative to transmitted light pulses. The phase shift of the time slots is varied stepwise after preset time intervals. Signals integrated during a time interval are digitalized, processed n a microprocessor and stored in a memory according to height values determined by respective phase shifts of the time slots. The micro-processors forms a smooth function of the signals accordint to height values, differentiates the smooth function, computes maxima and minima, determines maxima differing from a preset threshold value, and selects a maximum which with increasing height value is followed by a minimum.