Construction of scanning transmission optical microscope with aberration correction for convergent imaging system by the use of image processing

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The present study is based on results of the theoretical and experimental studies related to 'Aberration correction of imaging systems using active image processing method', under the support of past Grant-in-aid for scientific research for about ten years. The main aim of this study is the establishment of the aberration-free phase microscopy for transmission scanning microscopes, as an extension of the above aberration correction theory. And the second aim is the design and the construction of a prototype model of the aberration-free scanning transmission microscope to confirm the aberration-free imaging which realized the higher resolution over the probe size limit.According to these aims, the tree dimensional (3D) imaging theory for the scanning transmission microscope was developed from the 3D imaging theory for the conventional transmission microscope, under the basis of the 'reciprocity theorem' in the first stage (1999) of this study. Using the present extended 3D imaging theor … More y, computer simulations of the aberration-free imaging for the scanning transmission microscope was planned, and the program coding was begun in the first stage. The system design and program coding of the prototype model of the aberration-free scanning transmission microscope were also begun in this stage (1999). By the reason of difficulties on the reconstruction of the video electronic circuits in the laser scanning microscope used as the base, the prototype system was re-designed to equip fixed a 2D detector array instead of the single movable detector considered at fast. However, this re-design results in very long image acquisition time of about one day, for 256 x 256 pixels image.The prototype construction was carried out in the next stage (2000). Preliminary image acquisition was made for this system. The observed image was, however, very poor because of the lack of long time intensity stability of the HeNe laser light source. A sign of the wave front alteration due to the light probe scanning by AO modulator was also found, which should be avoided in this study. At present, this problem remains unsolved. We are now planning the re-design such as the addition of the light source stabilizer and the use of mechanical sample scanning unit for this prototype.On the other hand, the result on the simulation of aberration-free imaging clearly shows the higher resolution over the probe size limit as expected. Application of this aberration-free imaging technique to the transmission scanning electron microscope is highly desired in the near future, in addition to the optical scanning microscope. Less