Low-coherence interferometry in random media. II. Experiment.
We present experimental results of measurements of light backscattering from semi-infinite disordered media by low-coherence interferometry (LCI). These results are compared with the theory developed in part I [J. Opt. Soc. Am. A 17, 2024 (2000)]. A comparison of the experimental data with the theoretical formulas based on the coherent phase approximation allows us to extract substantial information about the structure of the studied media. Our results demonstrate that LCI is an effective optical technique for studying nonuniform media even in the case in which the dimensions of nonuniformities are much less than the wavelength of the scattered light.
The basic argument underlying the present approach is again that the qualitative nature of the observations from business surveys is just the consequence of how the survey is conducted. Indeed, the categorical responses are assumed to be initiated by some latent continuous variables. Now, the correlations among these variables can be estimated by the method of the polychoric correlation coefficient exposed in Chapter 3. Then, we may ask the following question: Using correlations between predictions and realizations estimated from business survey data, could we test on the latent variables, the necessary and sufficient condition for rational expectations?