This is used for image reconstruction. Another thing about the modulation of diffuser either it is phase or amplitude or both?
Hi Anwar
From the setup of the holographic diffuser, you should determine at least, from the expanded beam after the diffuser,two amplitude values (a) which correspond to known positions(Theta), in order to have a set number of the following equation:
A=a Cos(Theta) Equ.(1)
The two amplitude (a)values can be measured by a radiometer/spectrometer which correspond to known positions(Theta)i.e., Theta=00,900,1800,with respect to the measured intensity (A). Then you can solve Equ(1), for the values of the Theta, which correspond to the measured (a) values. Consequently, you can determine the phase distribution of expanded beam after the diffuser by solving Equ(1), for the values of the Theta, which correspond to the measured (a) values.
@Khaled, Thank you for detail explanation. I still have some confusion. The intensity measured through CCD and amplitude through spectrometer. But you write that the angle is know like 0,90 and 180 degree. Can you explain this point using eq.
theta=cos-1(A/a)
Once again thanks.
I meant take the intensity (A) reading from the expanded beam & the amplitude (a) from different know (Theta) perspectives. This step allows you to be sure that the measured (A/a) value corresponds to the right angle, the known Theta. Then, when you determine the amplitude(a) and the intensity(A), you can determine Theta from the proposed equation:
theta=cos-1(A/a)
Then to develop a phase distribution, of the expanded bean, take as much as possible reading of (A/a) to figure out the Thetas.
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