Transmission electron microscope and image observation method using it
Drift generated at the time of photographing a TEM image is corrected simultaneously with photographing, so that a TEM image free form influence of drift is photographed. While the TEM image is recorded, drift in the place out of the view field subjected to recording is measured from moment to moment by another TV camera or a position sensitive detector. Drift is corrected by the movement of the specimen due to a specimen holder or by the movement of the image due to an image shift coil.
1. A transmission electron microscope comprising:
an electron gun;
a specimen holding portion for holding a specimen;
a converging lens system for applying an electron beam emitted from the electron gun onto the specimen held in the specimen holding portion;
an imaging optical system for forming an electron beam enlarged image on the basis of the electron beam transmitted through the specimen;
recording means for recording the electron beam enlarged image;
observation means for observing a border area of the transmission image enlarged by the electron beam in the outside of a view field of the recording means;
measuring means for measuring a moving amount of the electron beam enlarged image observed by the observation means; and
correction means for correcting the moving amount while the electron beam enlarged image is recorded by the recording means.
2. A transmission electron microscope according to claim 1 , wherein:
the observation means is an image pick-up means; and
the measuring means measures the moving amount of the electron beam enlarged image by comparing an image newly acquired by the image pick-up means with an image picked up and stored by the image pick-up means in advance.
3. A transmission electron microscope according to claim 1 , wherein:
the observation means is a two-dimensional position sensitive detector; and
the measuring means measures the moving amount of the electron beam enlarged image by comparing a gravity center position of a luminance distribution newly acquired by the two-dimensional position sensitive detector with a gravity center position of a luminance distribution measured and stored by the two-dimensional position sensitive detector in advance.
4. A transmission electron microscope according to claim 1 , further comprising specimen moving means for changing the position of the specimen held in the sample holding portion, wherein the correction means corrects the moving amount by driving the specimen moving means to change the position of the specimen.
5. A transmission electron microscope according to claim 1 , further comprising electron beam deflecting means disposed between the specimen holding portion and the recording means, wherein the correction means corrects the moving amount by driving the electron beam deflecting means.
6. An image observation method for recording an electron beam enlarged image of a specimen formed by a transmission electron microscope in recording means, comprising the steps of:
observing a border area of the transmission image enlarged by the electron beam, by observation means disposed out of the view field of the recording means and storing the part of the electron beam enlarged image as reference data;
observing a part of the electron beam enlarged image by the observation means to acquire observation data while the electron beam enlarged image of the specimen is recorded by the recording means;
measuring an image moving amount of the electron beam enlarged image by comparing the observation data with the reference data; and
correcting the image moving amount while the electron beam enlarged image of the specimen is recorded by the recording means.
7. An image observation method according to claim 6 , wherein the reference data and the observation data are acquired by an image pick-up means.
8. An image observation method according to claim 6 , wherein the reference data and the observation data are acquired by a two-dimensional position sensitive detector.
9. An image observation method according to claim 6 , wherein the step of correcting the image moving amount is performed in such a manner that the position of the specimen is moved.
10. An image observation method according to claim 6 , wherein the step of correcting the image moving amount is performed in such a manner that the electron beam enlarged image is moved by electron beam deflection means disposed between the specimen and the recording means.