limitations are encountered it may be desirable to arrange a system of the fig5 type such that the returning signals from one laser pulse are used for the distant target 106 and the returning signals from a second pulse are used for the nearby aerosol particles represented at 501 in the fig5 drawing a 34 two pulse 34 system of this type can provide additional return signal processing time and possibly some signal processing simplification but incurs the expense of additional energy requirements according to another variation of the fig5 system provision may be made for measuring the strength of the signal returning from the aerosol particles 501 in order to estimate the atmospheric attenuation incurred by the laser beam and enable consideration of the target return signal strength as another facet of the target 39 s signature such data also allow estimation of the target physical size and reflectivity characteristics to be made the present invention therefore provides a number of advantages in a distal target vibration assessment system these advantages include the following a provision of a nonintergized or quiescent time between laser pulses in which returning signal energy may be examined for target distance and signal return characteristics b a reduction in the average power needed for system operation and in the power dissipation capability required of the laser apparatus c a segregation of nearby aerosol particle signals from the more distal target signals and the separate utilization of each of these signals this separate utilization in the present instance includes assessment of sensor platform vibration d a reduction of system noise signals through more actuate characterizing of platform vibrations e use of the same illumination pulse for the distal target and the nearby aerosols to further conserve illumination energy and permit timing and apparatus.