If the optical path difference
is less than the equivalent wavelength, the real phase distribution of object can be directly obtained without phase unwrapping by the dual-wavelength digital holographic interferometry.
The refractive index of coherent light is different in different media because of which the optical path difference
varies, leading to the movement of interference fringes [13, 14].
In the case of a volume hologram (or Bragg hologram), the Bragg condition occurs and hence Bragg diffraction in the formation of the image, as the optical path difference
between wavefronts reflected from successive layers of material (photopolymer in this case) is an integral multiple of the wavelength.
Using a laser and interference microscope, the following morphological properties of erythrocytes were determined: the optical path difference
(OPD), the surface area of the erythrocyte phase image (S), the physical height (Z), and phase volume of erythrocytes (V) .
In the spatial domain, V(x) is sampled at a finite set of optical path difference
locations [x.sub.i] with i [member of] [1, [N.sub.D]], and [N.sub.D] marks the number of sample points.
Upon exiting the medium these rays merge together but with phase retardance, due to the optical path difference
(OPD) encountered along the different courses traveled.
When the Senarmont method is used for the measurement of residual stress, the optical path difference
(OPD) is about 9nm for the previous methods.
It is shown in Figure 5(b) that except the blockage region, the phase slope is 1.96degree/mm (the results of 54 GHz), which is consistent with the theoretical prediction by the optical path difference
The reported value of the light speed c has to be corrected for a difference (with the ratio of path difference
to whole path)
The center burst corresponds to the zero optical path difference
configuration and the side bursts are the result of the optical path difference
through the sample etalon.