1. An in-line type polarization imaging apparatus comprising: at least one light source for supplying light including reference light and object light; an image pickup section capturing images of interference figures each formed from the reference light and the object light that reaches the image pickup section through an object; a reconstructed-image-producing section producing reconstructed images; a polarized-light-image-calculating section obtaining polarized-light images; a beam splitter splitting the light supplied from the light source into the reference light and the object light; a phase-shift-array section including first phase-shift regions and second phase-shift regions, and making (a) a phase of the reference light having entered the first phase-shift regions different from (b) a phase of the reference light having entered the second phase-shift regions, the reference light being a divisional portion of the light split by the beam splitter; and a beam-combining element combining the object light with the reference light having passed through the phase-shift-array section, the object light reaching after having passed through the object, wherein: the object light and the reference light each include a first polarized-light component polarized in a first direction and a second polarized-light component polarized in a second direction that is different from the first direction, both of which object light and reference light enter the image pickup section; the image pickup section simultaneously captures an image of an interference pattern including (i) a first interference figure formed by interference between the object light which has the first polarized-light component and the reference light which has the first polarized-light component and a first phase, (ii) a second interference figure foiined by interference between the object light which has the first polarized-light component and the reference light which has the first polarized-light component and a second phase, (iii) a third interference figure formed by interference between the object light which has the second polarized-light component and the reference light which has the second polarized-light component and the first phase, and (iv) a fourth interference figure formed by interference between the object light which has the second light component and the reference light which has the second polarized-light component and the second phase; the reconstructed-image-producing section (I) produces a first reconstructed image of the object in regard to the first polarized-light component, the first reconstructed image corresponding to the first interference figure and the second interference figure, after (a) extraction of pixels corresponding to the first interference figure and the second interference figure from the interference pattern and (b) pixel interpolation and (II) produces a second reconstructed image of the object in regard to the second polarized-light component, the second reconstructed image corresponding to the third interference figure and the fourth interference figure, after (a) extraction of pixels corresponding to the third interference figure and the fourth interference figure from the interference pattern and (b) pixel interpolation; and the polarized-light-image-calculating section obtains the polarized-light images from the first reconstructed image and the second reconstructed image, the polarized-light images corresponding to respective positions in each of the reconstructed images of the object, wherein the reconstructed-image-producing section (i) obtains two respective intensity distributions of the first polarized-light component and the second polarized-light component of only the reference light, (ii) calculates respective complex amplitude distributions of the first polarized-light component and the second polarized-light component from the first to fourth interference figures and the two intensity distributions of only the reference light, and (iii) obtains a first amplitude distribution and a first phase distribution each as the first reconstructed image in regard to the first polarized-light component and a second amplitude distribution and a second phase distribution each as the second reconstructed image in regard to the second polarized-light component, from the complex amplitude distributions, wherein the polarized-light-image-calculating section obtains the polarized-light images corresponding to respective positions in each of the reconstructed images of the object, from the first amplitude distribution and the first phase distribution of the object and the second amplitude distribution and the second phase distribution of the object.