Spectrometer for Surface Analysis and Method Therefor

Abstract

A spectrometer ( 10 ) for sample surface analysis by irradiation of the surface by primary particles and a corresponding method of surface analysis spectroscopy. The spectrometer ( 10 ) provides sample viewing and secondary charged particle collection substantially normal to the sample surface. A collection chamber ( 22 ) comprises a secondary charged particle lens arrangement ( 20 ) to focus the emitted particles in a downstream direction along a first normal axis ( 24 ) and thereby to define a charged particle optical crossover location ( 25 ); and a light-reflecting optical element ( 50 ) downstream of the lens arrangement and arranged to receive image light ( 41 ) and reflect it away from a second normal axis ( 42 ) for providing a viewable image of the surface. The optical element ( 50 ) is positioned at, or near to, the crossover location ( 25 ) and comprises an opening ( 52 ) therethrough, such that the focused particles pass through the opening for downstream spectroscopic analysis substantially without obstruction by the optical element.

1 . A spectrometer for surface analysis of a sample, the spectrometer comprising:
 an analysis area, at which location a surface of a sample may be placed, for irradiation by a source of primary particles; and   a collection chamber for receiving secondary charged particles emitted from the surface of the sample, the collection chamber having a first axis passing therethrough, the axis being substantially normal to the analysis area, the collection chamber comprising:
 an optical lens arrangement arranged in use to focus and/or collimate at least a proportion of image light received from the surface of the sample towards a downstream end of the collection chamber for providing a viewable image of the surface; 
 a charged particle mirror disposed substantially about the first axis and arranged in use to focus and/or collimate at least a proportion of the emitted secondary charged particles towards an off-axis exit aperture, such that at least a proportion of the focused and/or collimated secondary charged particles may pass through the aperture for undergoing spectroscopic analysis downstream thereof. 
   
     
     
         2 . The spectrometer of claim  19 , wherein the charged particle mirror comprises a mesh element.