from omega-2theta (w-2t) you transfer to Q (1/Aengstroem)

[Qx,Qy] = 1/lambda([sin(2t-w)+sinw],[cosw-cos(2t-w)])

this is then scaled with the lattice constants (rlu means relative lattice units); your lattice constants are already used to create your reciprocal space map. You can calculate your lattice parameter from the 2theta value using Braggs formula.

For the question of software - it is unclear to me how your data looks in the first place; the images you present have already been processed. Also it is unclear which type of measurement you present.

Hi Dr. Frontzek,

Thanks for your answer! I now understand how they transfer. But what's the physical interpretation behind this equation? I guess the '1/lambda[sin(2t-w)+sinw]' part is related to Braggs formula 2 d sin(t)=n lambda, but i'm confused by '1/lambda [cosw-cos(2t-w)]'. 

For the data, it's '.XRDML' document, we now use software 'X'Pert Epitaxy.exe' to open it. In some papers, I saw they rotated (103) RSM image by some degrees (like below),  but in our software, we can't do that. Thus I was asking if there's other software. By the way, I don't know why they rotated the image, too. Could you give me some suggestions? Thank you very much!

I'm keenly interested in all the answers!

Do feel welcome to review and post your comments on some of these related RG & LI posts below.

Thanks for sharing the knowledge :-)

https://www.flickr.com/photos/85210325@N04/14348488010/in/album-72157645018820696/

https://www.researchgate.net/post/How_do_I_compute_b_Burgers_Vector_correctly_using_the_Hirsch_approach_to_computing_dislocation_density_employing_XRD_rocking_curve_profile_analysis?_tpcectx=profile_questions

https://www.researchgate.net/post/What_is_the_best_way_to_interpret_REAL_TIME_3D_X_Y_o-2TH_o_ph_ch_reciprocal_space_relative_intensity_data_from_HRXRD_rocking_curve_analyses?_tpcectx=profile_questions

https://www.linkedin.com/pulse/nano-structural-meaning-xrd-data-converting-bragg-condition-ananth?trk=mp-reader-card

https://www.linkedin.com/pulse/imaging-nanostructure-75mm-production-grade-sic-4h-wafers-ravi-ananth?trk=mp-reader-card

The equation is a transfer to a new coordinate system. The cos w part is the second axis in your RSM (please see the picture from the RIGAKU manual Ravi sent - thanks btw.);

For the software - I guess everybody has their own solution, best idea is to google for some MatLab routine, xrdml sounds like a plain ASCII (rows and columns of numbers) so this might be easy. The rotation comes from the transformation. You have to define an w0 which coincides with your crystallographic direction; if w0 is not "0" it will lead to the rotation.