In one common arrangement, the laser beam is split into two, one known as the object beam and the other as the reference beam. The object beam is expanded by passing it through a lens and used to illuminate the subject. The recording medium is located where this light, after being reflected or scattered by the subject, will strike it. The edges of the medium will ultimately serve as a window through which the subject is seen, so its location is chosen with that in mind. The reference beam is expanded and made to shine directly on the medium, where it interacts with the light coming from the subject to create the desired interference pattern.
In one common arrangement the laser beam is split into two, one known as the object beam and the other as the reference beam. The object beam is expanded by passing it through a lens and used to illuminate the subject. The recording medium is located where this light after being reflected or scattered by the subject, will strike it. The edges of the medium will ultimately ser,ve as a window through which the subject is seen, so its location is chosen with that in mind. The ref,erence beam is expanded and made to shine directly on the medium, where it interacts with the light coming from the subject to create the desired interference pattern.