It is possible because most spots will belong to a unique grain orientation, with a small probablility that one grain creates two or even more symmetry-equivalent spots. Particularly reflections with high multiplicity may be affected. However, the biggest drawback in my opinion is the small number of grains. From the picture I get the impression that only a few dozen grains contribute. Statistically speaking, any ODF derived from such a low number would carry a large uncertainty. The number of grains should be >1000.

You should be able to build up an ODF from many single images, preferably from the same sample area but different sample orientations. First figure out what the sample orientation angles phi,psi are for each spot. Intensity is proportional to grain size. From phi,psi you can calculate two out of three Euler angles that determine the grain orientation.

Crystallographic Texture

http://www.msm.cam.ac.uk/phase-trans/texture.html

https://www.youtube.com/watch?v=pvr8HDpL7vc

The sample was a 200um (0.2mm) Aluminum foil. The incidence beam size was 1mm diameter. The foil was most probably rolled out of an Aluminum ingot that looked like this: http://cefacommoditiesintl.en.ecplaza.net/sitebuilder/images/2013614101533534.jpg. There are several highly deformed grains elongated in the rolling direction and sandwiched atop each other. The magnified image of the Laue transmission XRD 2D diffractogram clearly shows highly oriented grains simultaneously reflecting from the sampled area. Sub-grain structure will also be visible once the sample is rocked about the diffractometer axis. These sub-grains and nearly orientiented grains are presently visible (with limited clarity) in the real time 2D diffractogram below for Brand X aluminum foil Figure 6 :

In case of the absence of "preferred orientation" the Debye-Scherrer arc ought to be continuous. However, in practice this is seldom our observation. Here are some examples of foils like Ni, Al, Brass, fibers like Kevlar, Cotton etc. that show varying degrees of residual "preferred orientation" as a result most likely of the processing conditions they were each subjected to. In the case of Ni & Brass, the D-S arc is continuous but it is not uniform. The non uniformity of relative intensity in the D-S ring is indicative of the unequivocal presence of "preferred orientation" in the foil:

https://www.flickr.com/photos/85210325@N04/8008714677/in/set-72157632728981912

There must be some numerical method of using the relative intensity distribution along the Debye-Scherrer arc to determine the texture co-efficient of sorts for the sample, wouldn't you think? Any suggestions?

Stats as of 07:20hrs EST 5-30-2014 just after increasing number of topics to 5+ and sharing on RG & LI: 2 / 0 · 5 Answers · 60 Views 4 Followers

Image below gives an idea of the reciprocal space resolution (2-Theta space) of the Laue transmission XRD images for aluminum foil samples:

1. Cu K Alpha incident beam 1mm diameter with Ni K Beta filter.

2. 20 kV, 15mA, 0.3kW

3. Sample to Detector Distance (SDD) of 6.94mm.

4. Lead (Pb) beam stop 6mm diameter and 2mm thick disk. Outlined in Figure 2 below by yellow/white circle slightly "off-center" around 22 degrees 2-Theta. "Off center" is due to the fact that the center of diffraction (000) is not coincident with the center of the beam stop. The correct center of diffraction (000) is determined by employing the multiple reflections (111) & (200) then radially determining the unique center to them all in 2D.

6. 30fps, 8-10 frame average.

7. 76-78um detector pixel size.

8. Active X-ray input window was 25mm diameter.

https://www.flickr.com/photos/85210325@N04/7977700644/in/set-72157632728981912

A SYSTEMATIC EVALUATION OF STRAIN BROADENING FROM

STRETCHED ALUMINIUM FOILS USING A CONVOLUTION-FITTING

APPROACH TO LINE PROFILE ANALYSIS

R. W. Cheary, A. Coelho, WKalceff and M.Smith

Department of Applied Physics, University of Technology, Sydney,

P.O. Box 123, Broadway, NSW, Australia 2007.

"All the specimens used for the present work were prepared from commercial grade aluminium foil, O.lmm thick with a purity 99.5%, obtained from Alcoa Pty Ltd. This foil possesses a strong 100 texture perpendicular to the surface and the crystallite grains tend to be disc shaped, about 0.3um to 0.6um thick perpendicular to the foil surface and approximately 1um to 5um in the plane of the foil. Consequently some diffraction broadening arising from the small crystallite dimensions perpendicular to the surface will be present even in unstrained foils."

http://www.icdd.com/resources/axa/vol40/v40_626.pdf

Tom! "0.3um to 0.6um thick" over a 200um foil thickness implies a minimum 700-1000 grains/crystallites in the beam?

The following will improve the resolution of the Al foil Laue image:

1. Increasing the SDD.

2. Increasing the kW.

We normally do texture measurements from such images, check some of my articles in the last 10 years. If you want to use Maud software to extract the texture I advise to follow the article/tutorial on Powder diffraction in 2014 (there are 2 of them, the second one for more complex cases with high pressure or multiphase rocks.

Good work.

Luca