Universal study of the laser Intensity Calibration

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Universal study of the laser Intensity
Calibration

• Calibration methods
• ADK Saturation intensity
• 2 .Circular polarization
• 3.Beam size Radius of focal spot
• 4. Radius of focal spot
• 5.Comparison of intensity scale with published
  results
• Ratio(Ar2/Ar) vs intensity

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Calibration of intensity ADK theory
Comparison of theoretical yield predicted by ADK
with the experimental yield
Intensity Calibration constant0.8E12 watt/cm2
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Saturation intensity
For cylindrically symmetric , parallel beam
irradiation
Where ainstrument sensitivity c
concentration of neutral species l
length of cylinder w(t)intensity
dependent ionization rate f(t)pulse
profile
(S.M.Hankin et al. PRA 64 ,013405)
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Calibration of intensity of laser by measuring
the saturation intensity
Isat4E14
Isat457 Channel
1Ch(PD)0.87E12 watt/cm2
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Determination of the laser intensity by measuring
the recoil ion momentum resulting from
ionization by circularly polarized light
Yield
Where V100 volt d0.29 m
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By using D2 the circular polarization
Calibration constant0.97 E12 watt/cm2
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Measuring the intensity of the beam by using the
size of the beam falling on the converging lens
Intensity 2P / x Repetition rate x
pulse duration
25 fs
80 fs
aperture
Beam splitter
mirror(f10cm)
window
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Expressions used for calculation of change of
pulse duration
Where GVD Group velocity dispersion , t
thickness of glass used(3mm), D Dispersion
Parameter d Pulse duration before passed through
glass(25 fs) ? Pulse duration after passed
through glass (80 fs)
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Intensity calibration Measuring the diameter
of beam
Wo7.27 um
Calibration constant1.3E12 watt/cm2
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Measuring the waist of beam at focal plane of
lens by using ccd camera
Arrangement of lens ccd camera
F300mm
ccd
Objective lens (f8mm)
Z
wo for 10 cm lens6.2 um
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Measuring the intensity of beam at focal plane of
lens by using ccd camera
Expression Intensity2P / 3.14x(wo)2xrepetation
rate X Pulse duration Repetition
rate1KHz, Pulse duration80 fs
Calibration constant1.6E14 watt/cm2
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Comparison of intensity scale Argon ratio vs
intensity
4.5E14
4.9E14
(Th weber et al. JPB 33 L127)
(our scale)
knee
Knee feature that separates the sequential
ionization from The non sequential part
3.5E14
(C. Guo et al .PRA 58 R4271)
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