![]() Transmission Matrix: Measuring and Utilizing So the equation 7 maybe is not for the hadamard basis so that a unitary transformation is needed? If so, how to reconstruce the transmission matrix by getting the signal generated by hadamard basis?Ģ) if I want to optimise for optical focusing, following equation 16 can calculate the corresponding optimised phase pattern, so is the phase pattern displayed on the controlled part of the SLM directly? if so, will there be a problem leaving the reference part unchanged? I am concern about that the reference part can still reflect light into the scattering medium, which will interference with the optimised phase pattern on the controlled part. So once the measurement is completed, equation 7 can give us the observed transmission matrix directly, right? But the intensities are obtained from hadamard basis instead of canonical basis. I am a beginner in the field of wavefront shaping and I was attracted by your paper of LC-SLM-based transmission measurement.Ĭhecking your paper ‘ controlling light through optical disordered media: transmission matrix approach’, the region of SLM is divided into two parts: one is reference part and the other is controlled part.ġ) the measurement is proceeded by sending the hadamard basis on the controlled part while the reference part remain unchanged and then get the signal from CCD. What did I do wrong here?ĭigital Optical Phase Conjugation SLM orientation However I have power fluctuating and increasing all the way to nearly 2Pi (1000 value). My expectation is that the power would gradually increase to a peak at Pi (something between values of the pixel), then gradually reduce to near zero when the phase change reaches 2 pi (1024). I then changed the level of phase modulation at all lines (increase the value in the csv file) and observe increasing power at the 1st spot. I am now trying to use this for some experiment in the 1550 nm region and want to test to make sure that the SLM is working fine for that wavelength? Atm I made up a simple line grating with a pitch of 60 um (6 pixel) and diffract the zero-order to the 1st order when the grating is On. A graduate student has used the visible windows for a while and it seems to work ok. I am new to SLM so got a Santec SLM-100 with dual windows (visible and 1550 nm). Need Matlab codes for stepwise sequential algorithm, or transmission-matrix algorithm for focusing light in scattering media. I could not find any paper which actually did this but just wonder if it is something obvious that someone here can give me some light on? For the case of TM matrix measured on the complex field pattern then the number of SVs is the number of modes as shown in this paper I was told that if I do the SVD directly on the intensities obtained from different input (basically not applying the 4-phase or off-axis technique to extract the complex field pattern but just use the intensity vectors as column of the "intensity TM"), the number of SVs will be roughly twice the number of modes.My question is: After obtaining the TM, should I apply SVD on such TM and try to reduce it to a leaner version (less noisy) of the TM before testing the stuffs such as focusing or imaging? The TM for a multimode fibre should ideally has the rank of N (number of macro pixel on the SLM)? It is because I think the basic vectors of both left and right singular matrices are the same fibre modes, so that the TM would be an square vector of rank N.when the number of SVs is stable it indicates that all of the modes has been activated (assuming large NA input)Ĭan it be done that way? Here the paper they used the random pattern but they just say that 900 patterns is enough. Use a bigger set of random patterns, measure again the TM.Apply SVD on the TM, find SVs (say 98% of the total power).Use some set of random patterns and measure a TM.Is it absolutely critical to use a orthorgonal basis in the input? As for the case of a MMF, can I use random patterns as per the paper below.Could you please shed some light for me on the measurement of TM, for the case of a multimode fibre? ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |