To find d-values you have to know: camera lenth and wave length (or ht of a tem). then simply use L*wl=r*d, where L - camera length, wl-wave length, r- distanse from the center of your patter to the reflection.

See nearly the same question or many other:

https://www.researchgate.net/post/What_are_the_information_obtained_from_SAED_pattern_of_nanopoarticles2

Dear Varadha,

If the diffraction patterns are in DM3 or 4 format, you can download the free version of Gatan Digital Micrograph and directly measure the d spacing. If not, each d spacing is obtained multypling the camera lenght of the microscope for the wavelenght of your electron beam and dividing for the radius of each rings. (Eventually the Williams and Carter 's book contains the wavelenght values for different microscope voltages.)

So in the end, you need:

-camera lenght (information from the microscope, but also contained in the digital pictures)

-wavelenght that you can obtain from the TEM book if you know the working voltage of the used instrument

-r that is the radius that you measure on your Diffraction pattern

Sincerly

Ruggero

Thanks for the useful information.

With regards

varadhaseshan