Continuous-zoom imaging device of interferometer

#The present invention relates to a continuous-zoom imaging device of an interferometer and; more particularly, to a continuous-zoom imaging device, which can be widely applied to interference apparatuses, related measurement apparatuses utilizing the interference principle, related imaging devices of interference pattern, and common imaging devices.

#An interferometer is an apparatus utilizing the interference phenomenon of light for measuring optical devices or other physical parameters. How to effectively obtain the interference pattern is thus an important issue of this kind of apparatus.

#There are several kinds of interference systems, but their principle is very similar. With the commonly adopted Fizau type interferometer as an example, as shown in FIG. 1, an interferometer can be divided into two parts, one being a light projection system, the other being an interference pattern imaging system. Please refer to U.S. Pat. No. 4,201,473. The light projection system comprises a laser 10, a spatial filter 12, a splitter 14, a collimation device 16, a reference plane 18, and a test plane 20. In the interference pattern imaging system, reflected lights of the test plane 20 and the reference plane 18 interfere with each other to generate an interference pattern. The interference pattern passes through the collimation device 16, is vertically reflected by the splitter 14, then passes through a rotating diffuser 22, a zoom lens 24, and an attenuator 26, and is finally transmitted to a TV camera 28 to be read out. Therefore, the quality of the interference pattern depends on the imaging system.

#FIG. 1 is a structure diagram of a prior art interferometer;

#FIG. 2 is a diagram of an interference image formed in a prior art interferometer;

#FIG. 3 is a structure diagram of an interferometer of the present invention;

#An interferometer is generally divided into two parts, one being a light projection device used for generating projection light, the other being an interference pattern imaging device. The present invention improves the part of imaging device to achieve the same or more effects without using a rotating diffuser. In order to clearly illustrate the function of the present invention, the structure and action of the whole interferometer will be described in detail.

#As shown in FIG. 3, a light projection device comprises a laser 30 with an inbuilt spatial filter (not shown). A He—Ne laser light beam is outputted by the laser 30, passes through the inbuilt spatial filter to expand the laser light beam and achieve filtering effect, is reflected to an attenuator 36 for adjustment of light by a reflective piece 32 and a reflective mirror 34, is then reflected to and passes through a polarizing beam splitter (PBS) 40 including a quarter wave plate by a reflective mirror 38. The transmitted light is reflected in order by a rod mirror 42 and a primary mirror 44 and is then incident into a collimation device 46 so as to enter between a reference plane 48 and a test plane 50. The collimation device 46 is usually composed of collimation lens.

#The continuous-zoom imaging device comprises reflected lights of the reference plane 48 and the test plane 50, which interfere with each other to generate an interference pattern. Parallel light of the interference pattern is converted to a convergent light having the interference pattern by the collimation device 46. The interference pattern is then guided from the collimation device 46 to the PBS 40 by an optical path adjustment means formed of the primary mirror 44 and the rod mirror 42. The PBS 40 vertically reflects the interference pattern and guides it to an imaging passageway. Planar reflective mirrors 52 and 54 on the imaging passageway guide the convergent light of the interference pattern to a continuous-zoom device 56, which is composed of two zoom lenses 58. The distance between the two zoom lenses 58 is adjusted to magnify the object image. The continuous-zoom device 56 has a continuous magnification ratio between 1× to 6×, and is used to adjust the magnified ratio of the interference pattern on the imaging passageway and to output an object image. Because the continuous-zoom device 56 is directly placed on a focus plane of a charge coupled device (CCD) 60, it can directly image the object image on the CCD 60, which then converts the object image into electronic signals.