Electron beam contactless testing system with grid bias switching

A method for the contactless testing of electrical conductors disposed in and terminating on at least one surface of an insulating material specimen, comprising:

• (a) irradiating said one surface of said specimen with an electron beam while applying a positive bias potential to an entire conductive grid comprised of a plurality of conductive wires disposed above said one surface substantially parallel thereto and closely spaced to said one surface, whereby a uniform potential is applied to said one surface of said specimen;
• (b) irradiating selected portions of said one surface of said specimen with an electron beam at a first beam potential while said grid is biased at a negative potential;
• (c) irradiating selected portions of said one surface of said specimen with an electron beam at a second beam potential while said grid is biased at a potential greater than or equal to zero volts;
• and
• (d) detecting any change in potential of said electrical conductors irradiated by said electron beam at said second beam potential.

A method for the contactless testing of electrical conductors disposed in and terminating on at least one surface of an insulating material specimen, comprising:

• (a) irradiating said one surface of said specimen with an electron beam while applying a positive bias potential to a conductive grid disposed above said one surface substantially parallel thereto and closely spaced to said one surface, whereby a uniform potential is applied to said one surface of said specimen;
• (b) irradiating selected portions of said one surface of said specimen with an electron beam at a first beam potential while said grid is biased at a negative potential;
• (c) irradiating selected portions of said one surface of said specimen with an electron beam at a second beam potential while said grid is biased at a potential greater than or equal to zero volts;
• and
• (d) detecting any change in potential of said electrical conductors irradiated by said electron beam at said second beam potential
• (e) said first beam potential is greater than said second beam potential, and
• (f) said steps of irradiating said one surface of said specimen are carried out with a single scanning electron beam at said first and second beam potentials, and
• (g) said step of irradiating said specimen to apply a uniform potential thereto is carried out at said second beam potential.

A method for the contactless testing of electrical conductors disposed in and terminating on at least one surface of an insulating material specimen, comprising:

• (a) irradiating said one surface of said specimen with an electron beam while applying a positive bias potential to a conductive grid disposed above said one surface substantially parallel thereto and closely spaced to said one surface, whereby a uniform potential is applied to said one surface of said specimen;
• (b) irradiating selected portions of said one surface of said specimen with an electron beam at a first beam potential while said grid is biased at a negative potential;
• (c) irradiating selected portions of said one surface of said specimen with an electron beam at a second beam potential while said grid is biased at a potential greater than or equal to zero volts;
• and
• (d) detecting any change in potential of said electrical conductors irradiated by said electron beam at said second beam potential,
• (e) said first beam potential is greater than said second beam potential,
• (f) said second irradiating step is carried out with a flood beam while a negative bias potential is being applied to said grid, and
• (g) said third irradiating step is carried out with a scanning electron beam at said second beam potential while a positive bias potential is being applied to said grid.

A system for contactless testing of electrical conductors disposed in and terminating on at least one surface of an insulating material specimen, comprising:

• (a) a scanning electron beam generator for irradiating selected portions of said one surface of said specimen at first and second beam potentials;
• (b) a conductive grid comprising a wire mesh of conductors mounted above said one surface of said specimen, substantially in a plane parallel thereto and closely spaced to said one surface;
• (c) bias means connected to said grid for:
• (1) applying a negative first grid potential to all of said conductors of said grid while said selected electrical conductors are irradiated by an electron beam from said generator at said first beam potential, and
• (2) then applying a second grid potential to all of said conductors of said grid while said selected electrical conductors are irradiated by said electron beam at said second beam potential;
• and
• (d) detector means for sensing secondary electrons emitted from said one surface of said specimen.

A system for contactless testing of electrical conductors disposed in and terminating on at least one surface of an insulating material specimen, comprising:

• (a) a scanning electron beam generator for irradiating selected portions of said one surface of said specimen at first and second beam potentials;
• (b) a conductive grid comprising a mesh of first and second sets of parallel conductors mounted above said one surface of said specimen, substantially in a plane parallel thereto and closely spaced to said one surface, said first set being substantially orthogonal to said second set;
• (c) bias means connected to said grid for:
• (1) applying a negative first grid potential to all of said conductors of said grid while said selected electrical conductors are irradiated by an electron beam from said generator at said first beam potential, and
• (2) then applying a second grid potential to all of said conductors of said grid while said selected electrical conductors are irradiated by said electron beam at said second beam potential;
• and
• (d) detector means for sensing secondary electrons emitted from said one surface of said specimen.