Ballistic measurement systems: measuring time interval (1950 – 1970)

Measuring time interval (1950 – 1970)

The advent of digital techniques in the development of counters opened up a new possibility for accurate measurements in different research areas. This concerned in particular the determination of frequency or time interval between two consecutive events. Because commercial equipment was initially unavailable and/or did not comply with military requirements, the TNO Physics Laboratory developed between 1950 and 1970 three generations of time interval meters for the Royal Netherlands Army Testing Force. These meters were used when measuring flight times and when determining the speed of projectiles.

Time interval meter with valves

Time interval meter with valves
Time interval meter with valves (1950)

This device developed in 1950 determines the time interval in units of 1 microsecond up to 1 second. The readout is made with neon lights.

 

Time interval meter with transistors

This model, taken into use in 1962, measures in units of 1, 10 or 100 microseconds during 1, 10 or 100 seconds respectively. The numerical display uses digivisors, that are rotational reel meters with number plate 0 to 9, one of which is projected onto a frosted glass. [see E.A.C Digivisor Mark.2]

Time interval meter with transistors and digivisors (1962)
Time interval meter with transistors and digivisors (1962)

Time interval meter with integrated circuits

This time interval meter was in use from 1970 on. Time units 0.1, 1 or 10 microseconds for 1, 10 or 100 seconds respectively. The readout was with gas discharge numeral tubes.

Time interval meter with integrated circuits
Time interval meter with integrated circuits

Photoelectric detectors

Photoelectric detectors have been developed for starting and stopping time interval meters. Two of these detectors detect the passing projectiles and pass the signal to a time interval meter.

Photoelectric detector. The detector has many adjustment possibilities for the fan-shaped detection beam: gap width, gap length and with a zoom lens, the slit height setting
Photoelectric detector. The detector has many adjustment possibilities for the fan-shaped detection beam: gap width, gap length and with a zoom lens, the slit height setting

 

Openend detector
Opened detector

 

Measurement windows for projectiles with various ballistic measuring instruments under the windows. Each of the windows at fixed distances contain a single winding coil which detected magnetised projectiles.
Measurement windows for projectiles with various ballistic measuring instruments under the windows. Each of the windows at fixed distances contains a single winding coil which detected magnetised projectiles.