Patent Number: 
Section: claims

1. An electron microscope comprising:a support for supporting a specimen;a deflector for deflecting an electron beam to the specimen to form images;an image pickup device for obtaining the images; anda processor coupled to the image pickup device, said processor being programmed for observing the specimen in a field of view of the electron microscope, said programming causing the microscope to perform the acts of:presetting an arbitrary search target pattern similar to a search target form,determining whether the field of view has a brightness inappropriate for observation or search,adjusting electro-optical conditions of the electron microscope when it is determined that the field of view is appropriate for observation or search,searching the field of view for a form having the same pattern as the arbitrary search target pattern, andmeasuring a number of the forms obtained by the search;wherein said determining act is performed based on a degree of coincidence between one of said obtained images and a reference image which includes said arbitrary search target pattern. 2. An electron microscope comprising:a support for supporting a specimen;a deflector for deflecting an electron beam to the specimen to form images;an image pickup device for obtaining the images; anda processor coupled to the image pickup device, said processor being programmed for observing the specimen in a field of view of the electron microscope, said programming causing the microscope to perform the acts of:presetting an arbitrary search target pattern similar to a search target form,determining whether the field of view has a brightness inappropriate for observation or search,adjusting electro-optical conditions of the electron microscope when it is determined that the field of view is appropriate for observation or search,searching the field of view for a form having the same pattern as the arbitrary search target pattern, andmeasuring a number of the forms obtained by the search;wherein the processor is further programmed to preset a range of angles between sides of a pattern, ellipticity, and ratio in length between major or minor axes of the arbitrary search target pattern. 3. A sample observing method comprising the steps of:obtaining an image formed by irradiating an electron beam to a specimen;presetting an arbitrary search target pattern similar to a search target form;determining whether a field of view has a brightness inappropriate for observation or search;adjusting electro-optical conditions of an electron microscope when it is determined that the field of view is appropriate for observation or search;searching the field of view for a form having the same pattern as the search target pattern; andmeasuring a number of the forms obtained by the search;wherein said determining step is performed based on a degree of coincidence between the obtained image and a reference image which includes the arbitrary search target pattern.