Laser cloud height measuring device - has automatic cut=out or power redn. to prevent eye damage when laser is moved from vertical position

摘要

The measuring device includes an automatic switch for disconnecting the laser, or reducing the power to a level insufficient to cause eye damage, when the device is moved out of the operating position in which the laser is directed vertically upwards. The switch (9) responds to the device being moved through an angle greater than a given limit angle. Pref. the reduction in the power output of the laser is obtained by decreasing at least one of the following power amplitude; the peak pulse power; the pulse duration and the pulse frequency for the laser pulses. Pref. the power is reduced to a level which does not cause eye damage even when the laser pulses are viewed through a telescope. A gravity-operated switch is pref. coupled between the laser diode array and a pulse source in parallel with a resistor.