application_number US 94143486 A description this invention will be described with reference to the accompanying drawings in more detail fig1 is a block diagram partly as a sectional diagram an electron tube sectioned showing a first example of a high time resolution electron microscope unit according to the invention the body of the electron microscope unit hereinafter referred to as 34 an electron microscope body 34 when applicable includes a vacuum container 100 a means for supporting a specimen 103 in the vacuum container 100 has a transparent window 104 and a specimen holder 106 provided on the inner surface of the window 104 in the case where the specimen is a semiconductor chip variations of the semiconductor chip which are caused by the application of the aforementioned laser beam can be observed under the electron microscope a phosphor screen 140 is formed on the inner surface of the output surface of the container 100 which confronts with the specimen 103 electrons generated by the specimen 103 are accelerated by an accelerating means namely an electrode 110 with a hole towards the phosphor screen 140 a coil current source 112 supplies an excicing current to a focusing coil 111 so that electrons emitted from the specimen 103 are focused in enlarged form that is the focusing coil 111 forms an electron lens a gate means.