Incident Angle Correction

Incident angle correction factor. The correction factor of ref. 22 has been calculated for an incident angle range from 0° to 90° and for a vertical transmission ratio from 0 to 1. The correction is applied by dividing the observed intensities by correction factor K. Clearly, the correction factor remains unity for complete X ray absorption as well as for incident angles of 0°. 

An empirical correction that is used by some single-crystal diffractometers equipped with CCD cameras takes the following form  

Here m is a coelScient that parameterizes a detector-wavelength combination. For example, a CCD detector optimized for copper radiation used m = 0.1763. One optimized for molybdenum radiation had m = 0.3274. No derivation of this formulation has to date been published. 

Again no formal derivation of this correction has been published. 

A more complex function for imaging plates taking into consideration additional absorption of the excitation and emitted light has been proposed  

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Figure 14.15 Incident angle correction. The path of the incident ray through the detecting layer of thickness d depends upon the incident angle The length travelled within the layer is then

The incidence angle o is for a 10% blade thickness. For blades of other than 10% thickness, a correction factor K is used, which is obtained from Figure 7-25. 

The incidence angle now must be corrected for the Mach number effect The effect of the Mach number on incidence angle is shown in Figure 7-26. The incidence angle is not affected until a Mach number of. 7 is reached. 

Figure 7-25. Correction factor for blade thickness and incidence angle calculation.

Fluorescence spectra were recorded using an SLM 4800 spectrofluorimeter (Bioritech, Chamarande, France) fitted with a thermostat-controlled (30°C) front-surface accessory. The incidence angle of the excitation radiation was 60°. Coagulation kinetics were performed in a quartz cuvette 1 cm x 1cm. All spectra were corrected for instrumental distortions in excitation using a rhodamine cell in the reference channel. 

When reflection geometries are set up in modern scattering applications to study the structure of thin layers, the simplifying assumption of infinite sample thickness is not allowed, and the absorption correction becomes more difficult. Moreover, symmetrical-reflection geometry is utilized less frequently than asymmetrical-reflection geometry with fixed incident angle. Thus both cases are of practical interest. 

Figure 15 Incident angle dependences of the p-polarized absorbance of 4,4 -bipyridinium radical cations in LB films at 400 nm after correction of the decay and optical path length for photoexcited (a) HV2+/AA and (b) AV2+/AA systems. The solid lines are calculated dependences.

The incident angle of the reflected beam onto the detector is utilized in a factor often described as correcting for the flatness of a detector. The diffracted beam penetrates into the image plate or fluorescent layer of the detector. The penetration length depends on the angle of incidence and the linear attenuation factor for the utilized wavelength and fluorescent material. 

As already mentioned, the reflection modulation technique is relatively simple but for thicker or absorbing thin films it becomes much more complicated due to the multiple reflection effects in the used multilayer structure (Fig. 1) which may lead to erroneous results, if not correctly taken into account [10,20]. In that case, the measurement of the incidence angle dependence of the modulation intensity is required. Through a correct analysis of experimental data one can get both real and imaginary parts of r, as well as its anisotropy and ri3 tensor components). 

For the characterization of the layers, it is better to conduct the study at a set incidence angle, but quantitative studies will then be needed to correct the intensity measurements performed by the actual irradiated volume [TIZ 96],... 

Image equalisation to correct for the incidence angle dependence of the sea surface radar backscatter ... 

The thickness of the interface layer where the dopant concentration is different from that of the bulk is roughly estimated as follows. Since a molar extinction coefficient of carbazolyl chromophore in PVCz at 295 nm is 1.54 x 10 cra M", the depth where the excitation intensity is 1/e of the initial value is calculated to be 0.065 um under the normal condition. On the other hand, the penetration depth of the evanescent wave is a function of the incident angle, and it is difficult to calculate it here because the complex refractive index cannot be estimated correctly from the large absorbance at the laser wavelength. At present we can say that the TIR phenomenon was really observed and that the effective thickness under the TIR... 

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