v10309u Hamamatsu Photonics, K.K.,, v10309u Datasheet - Page 5

• Manufacturer Part Number: v10309u
• Description: Image Intensifiers
• Manufacturer: Hamamatsu Photonics, K.K.,

GGLOSSARY OF TERMS
GGLOSSARY OF TERMS
Photocathode Sensitivity
Luminous Sensitivity: The output current from the photocathode per
the input luminous flux from a standard tungsten lamp (color
temperature: 2856 K), usually expressed in µA/lm (microamperes per
lumen). Luminous sensitivity is a term originally for sensors in the
visible region and is used in this catalog as a guideline for sensitivity.
Radiant Sensitivity: The output current from the photocathode per
the input radiant power at a given wavelength, usually expressed in
A/W (amperes per watt).
Quantum Efficiency (QE): The number of photoelectrons emitted
from the photocathode divided by the number of input photons,
generally expressed in % (percentage). The quantum efficiency and
radiant sensitivity have the following relation at a given wavelength λ.
Luminous Emittance
This is the luminous flux density emitted from a phosphor screen and
is usually expressed in lm/m
luminous emittance from a completely diffused surface emitting an
equal luminance in every direction is equivalent to the luminance
(cd/m
Gain
Gain is designated by different terms according to the photocathode
spectral response range. Luminous emittance gain is used for image
intensifiers having sensitivity in the visible region. Radiant emittance
gain and photon gain are used for image intensifiers intended to detect
invisible light or monochromatic light so that light intensity must be
expressed in units of electromagnetic energy
Photon gain is also used to evaluate image intensifiers using a P-47
phosphor (see Figure 5) whose emission spectrum is shifted from the
relative visual sensitivity.
Luminous Gain: The ratio of the phosphor screen luminous emittance
(lm/m
Radiant Emittance Gain: The ratio of the phosphor screen radiant
emittance density (W/m
the photocathode. In this catalog, the radiant emittance gain is
calculated using the radiant flux density at the wavelength of maximum
photocathode sensitivity and the radiant emittance density at the peak
emission wavelength (545 nm) of a P-43 phosphor screen.
Photon Gain: The ratio of the number of input photons per square
meter at a given wavelength to the number of photons per square
meter emitted from the phosphor screen.
MTF (Modulation Transfer Function)
When a black-and-white stripe pattern producing sine-wave changes
in brightness is focused on the photocathode, the contrast on the
output phosphor screen drops gradually as the stripe pattern density is
increased. The relationship between this contrast and the stripe
density (number of line-pairs per millimeter) is referred to as the MTF.
Limiting Resolution
The limiting resolution shows the ability to delineate image detail. This
is expressed as the maximum number of line-pairs per millimeter on
the photocathode (1 line-pair = a pair of black and white lines) that can
be discerned when a black-and-white stripe pattern is focused on the
photocathode. In this catalog, the value at 5 % MTF is listed as the
limiting resolution.
EBI (Equivalent Background Input)
This indicates the input illuminance required to produce a luminous
emittance from the phosphor screen, equal to that obtained when the
input illuminance on the photocathode is zero. This indicates the
inherent background level or lower limit of detectable illuminance of an
image intensifier.
Shutter Ratio
The ratio of the brightness on the phosphor screen during gate ON to
that during gate OFF, measured when a gated image intensifier is
operated under standard conditions.
QE =
2
2
) multiplied by π.
) to the illuminance (lx) incident on the photocathode.
S × 1240
λ
× 100 (%)
2
) to the radiant flux density (W/m
2
(lumens per square meter). The
S: Radiant sensitivity (A/W)
λ : Wavelength (nm)
2
) incident on
Dark Count
This indicates the noise level of an image intensifier using a 3-stage
MCP when operated in the photon counting mode.
The dark count is usually expressed as the number of bright spots per
square centimeter on the photocathode measured for a period of one
second (S
Cooling the photocathode is very effective in reducing the dark count.
Usually, photocathodes (such as red-enhanced or extended red
multialkali, GaAs and Ag-O-Cs) that tend to produce a large number of
dark count at room temperatures should be cooled when used in the
photon counting mode.
Pulse Height Distribution (PHD) on Phosphor Screen
Bright spots appear on the output phosphor screen when an image
intensifier using a 3-stage MCP is operated in the photon counting
mode. The pulse height distribution is a graph showing how many
times a bright spot occurs on the phosphor screen, plotted as a
function of brightness level (pulse height).
When an image intensifier is used with the MCP gain saturated, the
brightness of each spot corresponding to each photoelectron is
equalized on the phosphor screen to allow photon counting imaging.
As noted in the graph below, the pulse height resolution and the P/V
(peak-to-valley) ratio are used to indicate how the bright spots are
aligned.
Fiber Optic Plate (FOP)
The FOP is an optical plate comprising some millions to hundreds of
millions of glass fibers with 6 µm diameter, bundled parallel to one
another.
The FOP is capable of transmitting an optical image from one surface
to another without causing any image distortion.
IStructure of FOP
Light
Optical fiber
Light is transmitted from one end to
the other while reflecting from the
surfaces repeatedly.
Reflection
-1
/cm
6 µm
2
).
A
PHOTON SPOTS BRIGHTNESS
Light
Fill Width
Half Maximum
FWHM
GPV Ratio =
GPulse height
An FOP is made up of a bundle of 50 million
optical fibers.
resolution
Each individual optical fiber transmits light
and this light can be received as an
image.
VALLEY
=
PEAK
FWHM
A
: 1
× 100 (%)
Light
TMCPC0079EA
TII C0061EA
Light
4