Patent ID: 8227781

Claim:
An apparatus for monitoring sample milling in a charged-particle instrument; the charged-particle instrument having a tilt stage, where the tilt stage has a maximum range of tilt; and an ion-beam column for producing an ion beam; the ion beam column having an ion-beam column axis; the apparatus comprising: a variable-tilt specimen holder attached to the tilt stage; the variable-tilt specimen holder further comprising: a first pivoting plate rotatably supported in the variable-tilt specimen holder; the first pivoting plate having a slot for holding a specimen from a sample, where the specimen has a preferred axis for thinning by the ion beam; the first pivoting plate having a range of rotation sufficient to move the preferred axis of thinning of the specimen from: a first position where the tilt stage is placed at its maximum range of tilt and the angle between the preferred axis of thinning of the specimen and the axis of the ion beam column is greater than zero to: a second position where the preferred axis for thinning of the specimen is substantially parallel to the ion-beam column axis; a second pivoting plate; the second pivoting plate rotatably supported adjacent to the first pivoting plate; a light detector; the light detector supported on the second pivoting plate; a light source; the light source directed so as to pass light through the specimen and to the light detector when the specimen is positioned by the first pivoting plate to a preferred axis of thinning and the second pivoting plate is positioned to intercept light passing through the specimen.