초록 ▼

Electro-optical in-circuit testing, especially of large circuits such as those assembled on printed circuit boards, is achieved in an automatic test system by disposing an electro-optical sensor in proximity to the circuit conductors, applying test signals to the circuit under test, and measuring an

Electro-optical in-circuit testing, especially of large circuits such as those assembled on printed circuit boards, is achieved in an automatic test system by disposing an electro-optical sensor in proximity to the circuit conductors, applying test signals to the circuit under test, and measuring an optical property of the sensor at selected regions thereof corresponding to internal nodes, i.e. test points, of the circuit. The sensor may be an optical probe, having a lens and a layer of electro-optical material which is adapted to be applied to the circuit. The electro-optical material may be either a polymer film or a crystal, the latter requiring a flexible coupling medium on the face applied to the circuit under test. The electro-optical material is provided with a reflective coating on one surface to facilitate a polarimetric measurement made transverse to the plane of the material. Another type of optical probe has a layer of electro-optical material with electrodes on the surface opposite the surface applied to the circuit under test. A polarimetric measurement is made by suitably biasing the electrodes and detecting light that passes through the material parallel to its surfaces. In another type of optical probe, the electro-optical material is coated on both surfaces, one coating being highly reflective and the other being semi-transparent. An interferometric measurement is provided by this type of sensor. Moreover, the polymer film may be applied directly to the printed circuit board during manufacture, in which case the lens is brought into contact with the electro-optical material during circuit testing.

대표청구항 ▼

An apparatus for testing a circuit having conductive circuit elements disposed proximate a surface thereof, comprising: sensor means having a conformable property so as operatively to expose electro-optical material in said sensor means to voltages in the circuit; means for establishing an electric

An apparatus for testing a circuit having conductive circuit elements disposed proximate a surface thereof, comprising: sensor means having a conformable property so as operatively to expose electro-optical material in said sensor means to voltages in the circuit; means for establishing an electric field between said conductive circuit elements and an interior of said sensor means, through electro-optical material within said sensor in a direction substantially normal to said circuit surface; means for applying test signals to said circuit; means for measuring at selected positions within said electro-optical material an optical property of said electro-optical material influenced by said electric field, said optical property varying in substantial synchronism with signals on said conductive circuit elements; and means responsive to said measuring means for determining a test parameter; wherein: said circuit includes conductors corresponding to external circuit nodes, and said conductive circuit elements include conductors corresponding to internal circuit nodes; said electro-optical material is provided with discrete electrodes on a surface opposite another surface nearest said circuit surface; said applying means comprising means for applying a pattern of electrical test signals to said external circuit node conductors; and said measuring means comprises: means for directing polarized light through one end of said electro-optical material in a direction generally parallel to the opposing surfaces thereof; means for biassing selected ones of said electrodes; and means for receiving light from an opposing end of said electro-optical material in a selected receiver, the output thereof being indicative of an optical property at a selected region of said electro-optical material electrically proximate a nearest one of said internal circuit node conductors.