FEATURES

A temporal resolution of 2 ps is achieved for both synchroscan

and single shot.

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Several plug-in module, operating mode.

Accommodates a diverse range of experimental setups

from single light emitting phenomena to high-speed

repeated phenomena in the GHz.

Can be used in X-ray to near infrared fields

By selecting the appropriate streak tube (light sensor), the

C5680 can be used in a wide range of measurement appli-

cations, from X-rays to near infrared light.

Simultaneous measurement of light intensity on

temporal and spatial (wavelength) axes

Spectrograph can be placed in front of the streak camera, to

convert the spatial axis to a wavelength axis. This enables

changes in the light intensity to be measured over various

wavelength (time-resolved spectroscopy).

The streak tube converts light into electrons which are then

multiplied by an electron multiplier. This enables detection of

extremely faint light (at the single-photon level).

(See photon counting integration principle)

IEEE-488 (GP-IB) control

Computer control enables remote control and advanced

measurements to be performed out using very simple op-

eration.

Diverse selection of peripheral equipment

A full lineup of peripheral devices is available, including

spectroscopes, optical trigger heads, and expansion units.

OPERATING PRINCIPLE

The light pulse to be measured is projected onto the slit and is

focused by the lens into an optical image on the photocathode

of the streak tube. Changing the temporal and spatial offset

slightly each time, four light pulses, each with a different light

itensity, are introduced through the slit and conducted to the

photocathode.

Here, the photons are converted into a number of electrons

proportional to the intensity of the incident light. The four light

pulses are converted sequentially to electrons which are then

accelerated and conducted towards the photocathode.

As the group of electrons created from the four light pulses

passes between a pair of sweep electrodes, a high voltage is

applied (see above), resulting in a high-speed sweep (the elec-

trons are swept in the direction from top to bottom). The elec-

trons are deflected at different times, and at slightly different

angles in the perpendicular direction, and are then conducted

to the MCP (micro-channel plate).

As the electrons pass the MCP, they are multiplied several

thousands of times and are then bombarded against the phos-

phorscreen, where they are converted back into light.

The fluorescence image corresponding to the first incident

light pulse is positioned at the top of the phosphor screen, follo-

wedby the others, with images proceeding in descending or-

der; inother words, the axis in the perpendicular direction on

the phosphor screen serves as the temporal axis. The bright-

nesses ofthe various fluorescence images are proportional to

theintensities of the corresponding incident light pulses. The

positions in the horizontal direction on the phosphor screen

correspond to the positions of the incident light in the horizon-

tal direction.

THE PRINCIPLE OF PHOTON COUNTING INTEGRATION

Photoelectrons given off from the photocathode of the streak

tube are multiplied at a high integration rate by the MCP, and

one photoelectron is counted as one intensity point on the

phosphor screen. A threshold value is then used with this pho-

toelectron image to clearly separate out noise.

The operating principle of the streak camera

Positions in the photoelectron image which are above the

threshold value are detected and are integrated in the memory,

enabling noise to be eliminated completely. This makes it possi-

ble to achieve data measurements with a high dynamic range

and high S/N.

Photon Counting Integration

Separation of Photoelectron

Image and Noise

Optical

intensity

Time

Space

Trigger signal

Slit

Lens

Incident light

Photocathode

(light

→ electrons)

Accelerating electrode

(where electrons

are accelerated)

Phosphor screen

(electrons

→ light)

MCP

(which multiplies

electrons)

Streak image

on phosphor screen

Time

Space

Sweep electrode

(where electrons

are swept in the

direction from top

to bottom)

Sweep circuit

The intensity of the incident light

can be read from the brightness

of the phosphor screen, and the

time and space from the position

of the phosphor screen.

A/D

conversion

value

Signal output from CCD camera

Time

(wavelength)

Noise

Photoelectron image

Threshold

value

0ps

Light source: PLP (

λ = 800 nm)

Integration time: 1 min.

200ps 400ps 600ps 800ps 1ns 1.2ns 1.4ns 1.6ns 1.8ns

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