| 摘要 |
A differential imaging technique is performed by the following steps: (i) illuminating the sample (8) surface with uniform, monochromatic light (2) and capturing a first image of the reflected light with a CCD camera (15), (ii) uniformly and precisely changing a physical parameter of the sample (8), (iii) repeating step (i) to capture a second image influenced by the new value of the physical parameter, (iv) subtracting the first and second images and dividing the result by the average of the images to produce a normalized difference image. The physical parameter may be temperature, electric field, light exposure, magnetic fields, or mechanical stress. The image produced is of the differential reflectance of the sample (8) surface at a given wavelength. Differential reflectance is equal to the change in reflectance due to the parameter change divided by the average reflectance.
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