Lidar arrangement for measuring atmospheric turbidities

A warning device for signalling a distance of a motor vehicle from a viability obstacle, comprising a lidar installed in a motor vehicle, said lidar including means for transmitting a cone of pulsating radiation, the cone having a given apex angle;

• means for receiving a part of the transmitted radiation backscattered from an obstacle, the receiving means including two receiving devices each having reception region which is spatially separated from that of the other device;
• polarization analyzing means arranged in said receiving means to split the backscattered parts of radiation received on said separate reception regions into two partial beams forming right angles one with the other;
• each of said receiving devices having two electro-optical detectors arranged in the path of said partial beams to determine backscattered radiation intensity according to polarization components of radiation oriented parallel and perpendicularly to the polarization direction of the transmitted radiation cone;
• means for evaluating output signals from said detectors to determine the kind of a visibility obstacle;
• means for evaluating time intervals between transmitted and received radiation pulses to determine from distance of said obstacle;
• and warning means for signalling the determined distance of a motor vehicle from said obstacle.

A lidar for measuring various atmospheric turbidities, comprising means for transmitting a cone of linearly polarized radiation, said cone having a given apex angle;

• means for receiving backscattered part of the transmitted radiation, said receiving means having a first receiving device provided with first means for detecting intensity of receiving radiation backscattered in directions parallel to the transmitted cone and polarized parallel to the polarization direction of the transmitted cone;
• second detecting means for detecting intensity of received radiation backscattered in the directions parallel to the transmitted cone and being polarized perpendicularly to the polarization direction of the transmitted rays;
• and means for evaluating from the ratio of intensity signals of the first and second detecting means;
• a second receiving device with means for detecting a part of the backscattered radiation which is outside the range of the radiation part received by said first receiving device;
• said evaluating means measuring from the ratio of output signals of the detecting means of the second receiving device to the output signal of said first and/or second detecting means of said first receiving device the atmospheric turbidities;
• and said first and second detecting means of the first detecting device receiving only the part of the backscattered radiation whose directions coincide with those of the transmitted cone.