RECENT DRDO DEVELOPMENTS
Threshold Detector Unit
The Laser Science & Technology Centre (LASTEC), Delhi, has developed a Threshold Detector Unit which is essential for the evaluation of electrooptic countermeasure (EOCM) class of solid-state laser systems in field conditions over long ranges. It is not available commercially in the format desirable for such a diagnostic application. Measurement of energy density requires absolute value of the energy as well as the spot size at the target point. Even if the required parameters are computed, i.e., energy density from the measured values of energy and spot size using conventional equipment, the process will be highly cumbersome as the spot sizes typically range from a few centimeters to few meters in realistic battlefield ranges. The detector eliminates the need for such a cumbersome test set-up and gives the desired information directly in a compact single gadget.
The detector unit has selectable energy density threshold level, and at a selected energy density level, it is capable of establishing whether the energy density at the desired target point is above or below the preset threshold level. When the energy density at the target point is more than the set value, the unit gives both an audio and a visible indication. While the audio buzzer sound has been provided for information of the technical personnel sitting inside the instrumentation vehicle on the outcome of the laser shot fired, the glowing flash- light is for the personnel at the source end. The intensity of light is so high that it can be seen from a distance of more than 2 km even during the day time.
The detector unit can be used with both free running and Q-switched types of pulsed solid-state lasers and can be selected with the help of a switch. The system is capable of handling Q-switched laser pulses from 10 ns to 100 ns pulse duration and free running laser pulses from 100µs to more than 600µs . It has a wide measurement range offering three possible range selections of 5µ J/cm2 to 50 J/cm2; 5 mJ/cm2 to 50 mJ/cm2 and 5 J/cm2 to 50 J/cm2; thus making possible the evaluation of EOCM lasers producing pulse energies from hundreds of millijoules to several kilojoules. The range selection is done by using a different calibrated front-end attenuator assembly. Each range setting has further 10 selectable threshold levels. The detector unit has a provision for auto shutoff after 15s to enable firing of multiple shots. It is battery operated and needs no human intervention at the target point.
The detector unit has been tested in the field with both types of lasers covering pulse energy range of less than a joule to kilojoule levels covering ranges from tens of meters to 2 km.
Auto Adjustable Stretcher
The Institute of Nuclear Medicine & Allied Sciences (INMAS), Delhi, has indigenously designed and developed a prototype auto adjustable stretcher for Autoadjiis~tcher comfortable movement of ambulatory patients. The prototype keeps the patient in the horizontal position irrespective of the slope, thereby mitigating the patients discomfort during movement of stretcher on ramps. The whole process of balancing has been managed by the sensors which are solid,state devices based on the principle of loss of eddy current. When any metallic sheet (in this case the stretcher bed) enters in the field, the eddy current increases and the amplitude of oscillation of the electromagnetic field is consequently reduced. This is fed to the DC switches which can be regulated. Another novel feature is the development of gear system which takes care of the movement of bed according to the demand given by the sensors.
Motorised Wheel Chair
INMAS has also developed a motorised wheel chair for rehabilitation of the handicapped persons. The main features of this chair are that it is cost,effective, indigenously developed, driven by permanent magnet motor, easy to operate, provided with rechargeable batteries and, has a manual switching system. The chair was displayed at the ACCESS 2000 Exhibition organised by the Ministry of Social Justice & Empowerment at Lucknow, recently.