Gated Optical Imager
Optical gate profiles Measurement method HRI 1MHz GOI Ultrafast GOI Normal GOI	GOI-HRI links Imagers Intro Photocathode responses ----HRI links---- HRI tutorial HRI_GOI unit Sinusoidal modulation HRI pictures ----GOI---- GOI intro GOI tutorial 1MHz GOI 4 frame GOI 50ps gate GOI -----Gating measurements----- Measurement method HRI 1MHz GOI Ultrafast GOI Normal GOI

The GOI is a microchannel plate intensified, gated single frame camera with a minimum gate open time of 120ps fwhm over a full 18mm diameter cathode aperture. It is easily interfaced to a CCD readout system. The small size allows several images to be packed together to provide a multi-framing capability.

The camera uses an entirely solid state electronic pulser to give super fast gating speeds. This novel technology gives low jitter, less than 20 ps RMS, combined with a small trigger delay, typically 18 ns plus cables. The modular form of the electronics allows easy change of the gate times.

The camera has three modes of operation: DC on, slow gate (~10µs to 1ms) and fast gate (120 ps to 5ns). It may be used as a fast camera or as an image intensifier. The DC mode allows easy focusing and set up.

The proximity focused wafer tube design gives a large number of pixels across the cathode. The resolution is typically 10 lines per mm.

The input window to the wafer tube may be either glass, fibre optic or, for extended blue response, quartz. The cathode is processed to respond to 850nm light permitting easy characterisation with a laser diode (not included in the package).

The camera head is 52mm square and 65mm. The camera is available in a four frame version in which four detector heads are close packed on a 54mm square (54mm between adjacent optical axes).

Options include film output and UV optics. With UV optics a lens or mirror must be used to form the image on the cathode plane at the rear, inner side, of the quartz window. With the normal fibre optic input window the image must be on the front, outer, face of the detector. This allows images to be transported with fibre bundles to the detector head.

The normal version of this system uses a gating mesh over the input; we can also offer a mesh free system to special order.

A single channel GOI head with drive electronics attached. Typical optical gate profile from a single channel system with video CCD readout. (100ps per division horizontal [right to left], optical gain vertical)

Tube Specification Type 18mm microchannel plate intensified wafer tube. Gating method Cathode to microchannel plate voltage switched. Cathode S20/S25 Output phosphor P20 /P43 Input window: Fibre optic, glass or plain quartz Output window: Fibre optic Resolution ~10 line pairs per mm Shortest gate <120ps FWHM (possibly less to special order) 65ps on 11mm tubes Gate modes 120ps to 5ns, 10µs to 1ms and DC Triggering Whole system requires single trigger ~25ns before event. >10 volts into 50 ohms with rise time <5ns. * No fibre optic input is available with UV cathode, so lens or mirror imaging must be used for this option.

Typical optical gate profile from an 11mm ultra fast GOI.

Other possibilities high repetition rate systems HRI larger aperture systems (with some loss of temporal resolution) 250ps on 40mm tubes RF modulated gain systems HRI higher dynamic range readout systems (non video) faster gating is possible particularly on smaller tubes 50 -65ps on 11mm tubes Ultra Short Gate GOI

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