This RC time constant gives rise to a diffusion of charge towards the tube axis and the diffusion rate cannot be increased by external drive circuitry, consequently the tube gate time achievable with conventional gating is limited. This limitation is avoided with the Kentech gating scheme. A highly conducting mesh is placed in front of the input window of the tube and this is pulsed to a high voltage. Most of the voltage appears between the mesh and the cathode but sufficient also appears between the cathode and the MCP input surface to gate the tube quickly.
More recently we have employed gating rings rather than meshes. These require even more voltage to drive them but are useful when imaging coherent light that may diffract badly through a mesh.
When considering the input to an array of these devices one may choose either wavefront or intensity division. Wavefront division will effectively produce a picture from a different angle of view onto each channel. Often this may be satisfactory but some events are significantly anisotropic and intensity division of the incident light may be necessary. In such a case there must be sufficient light to produce an image on each channel. Kentech is happy to advise on such schemes.
Lidar is also a possibility. imaging through scattering media, partiucularly fog or possibly underwater if the scattering is not too serious can be improved greatly by the added contrast that time range gating can bring to the imaging problem. In addition one may image through self luminous media. e.g. fires, as the light source can have a much greter peak brightness than the medium and the gated detector can use this peak brightness effectively.