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

1 . The optical gate for determining a velocity vector of a spherical projectile, comprises

a sensor array defined by a row of light detecting sensors arranged next to each other, and

an illuminating array defined by a row of point light sources arranged next to each other and illuminating towards the sensors,

wherein the illuminating array is arranged opposite the sensor array,

said illuminating array and said sensor array being arranged in a common plane, and

an optical diffuser plate being arranged between said illuminating array and said sensor array,

said light detecting sensors defining a detection area on said diffuser plate parallel to said sensor array, and

the optical gate further comprises

an electronic control unit configured to consecutively flash the point light sources at predetermined time instants at high frequency, and

an electronic measuring unit for processing the signals generated by the light detecting sensors, said measuring unit being configured to determine the brightness distribution and total brightness along the detection area based on the data generated by the sensors of the sensor array.

2 . The optical gate according to claim 1 , wherein the plane of the diffuser plate and the common plane are perpendicular to each other.

3 . The optical gate according to claim 1 , wherein the electronic control unit and the electronic measuring unit are configured as part of a common IT unit.

4 . The optical gate according to claim 1 , wherein the sensor array comprises a plurality of sensor groups formed by adjacent sensors and aggregating signals from the sensors.

5 . The optical gate according to claim 1 , wherein the point light sources are configured as LED light sources.

6 . The optical gate according to claim 1 , wherein the sensor array and the illuminating array are arranged along parallel lines.

7 . 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.

8 . The method according to claim 7 , further comprising at least one of the detection planes is selected as a plane connecting a side of the detection area parallel to the sensor array with the illuminating array, or as a common plane connecting the illuminating array to the sensor array.

9 . The method according to claim 7 , further comprising determining the total brightness associated with the time instants of arrival of the projectile at the detection volume and departure of the projectile from the detection volume by interpolating the measured total brightness.

10 . The method according to claim 7 , further comprising determining the total brightness measured at the crossing time corresponding to the intersection of the given detection plane by interpolating the measured total brightness.

11 . The method according to claim 7 , further comprising determining the brightness distributions measured along the detection area in the case of a flash of a given light source at the crossing time corresponding to the given detection plane, by interpolating the measured brightness distributions.

12 . The method according to claim 7 , further comprising the point light sources have a flashing frequency of at least 1 MHz.

13 . 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.

14 . The method according to claim 13 , further comprising determining the total brightness at the crossing time of a given common plane by interpolating the total brightness measured in the given detection area.

15 . The method according to claim 13 , further comprising determining the brightness distributions measured along a given detection area in the case of a flash of a given light source at the crossing time corresponding to the given common plane, by interpolating the measured brightness distributions.

16 . The method according to claim 13 , further comprising the point light sources of the first and second illuminating arrays have a consecutive flashing frequency of at least 1 MHz.

17 . The optical gate according to claim 5 , wherein the LED light sources are infrared LED light sources.