Optical gate and method for determining a velocity vector of a spherical projectile

A method for determining a velocity vector of a spherical projectile using an optical gate, the method comprising:

• providing a detection volume bounded by the detection area and by first and second boundary planes;
• connecting the sides of the detection area parallel to the sensor array with the illuminating array, in the measurement volume,
• defining a first detection plane connecting a first baseline of the detection area parallel to the sensor array with the illuminating array,
• defining a second detection plane connecting a second baseline of the detection area parallel to the sensor array with the illuminating array, and
• passing a spherical projectile through the detection planes, the method further comprising:
• flashing the point light sources of the illuminating array consecutively by means of the control unit, while determining the brightness distribution and the total brightness along the detection area for each flash of the point light sources by means of the sensors of the sensor array and the measuring unit,
• based on the measured total brightness, determining the time instants of arrival of the projectile at the detection volume and of its departure from the detection volume,
• given the arrival and departure times and the size of the spherical projectile, determining crossing times corresponding to the intersections of the projectile on the first and second detection planes, and
• for each of the detection planes:
• for a plurality of point light sources of the illuminating array, determining the brightness distribution measured along the detection area in the case of a flash of a given light source at the crossing time,
• determining the position of the projectile in the given detection plane at the crossing time by combining the brightness distributions thus determined for the different light sources, and
• determining the velocity vector of the projectile based on the positions and crossing times obtained.

A method for determining a velocity vector of a spherical projectile, comprising at least two optical gates arranged in series, of which a first optical gate comprises a first illuminating array, a first sensor array and a first common plane defined by the first illuminating array and the first sensor array, and a second optical gate comprises a second illuminating array, a second sensor array and a second common plane defined by the second illuminating array and the second sensor array, passing a spherical projectile through the first and second common planes, the method further comprising:

• flashing the point light sources of the first illuminating array consecutively while determining, for each flash of the point light sources, the brightness distribution and the total brightness along the first detection area of the first optical gate,
• determining a first crossing time corresponding to the minimum of the measured total brightness, for a plurality of point light sources of the first illuminating array,
• determining the brightness distribution measured along the first detection area in the case of a flash of a given light source at the first crossing time, and
• determining the position of the projectile in the first common plane at the first crossing time by combining the brightness distributions determined for the different light sources,
• flashing the point light sources of the second illuminating array consecutively while determining, for each flash of the point light sources, the brightness distribution and the total brightness along the second detection area of the second optical gate,
• determining a second crossing time corresponding to the minimum of the measured total brightness, for a plurality of point light sources of the second illuminating array,
• determining the brightness distribution measured along the second detection area in the case of a flash of a given light source at the second crossing time, and
• determining the position of the projectile in the second common plane at the second crossing time by combining the brightness distributions thus determined for the different light sources, and
• determining the velocity vector of the projectile based on the positions and crossing times obtained for the first and second common planes.