Method of focusing optical head on object body and optical inspection system comprising an automatic focusing device

Claim 2

The method of claim 1, further comprising the step of: (k) repeating the steps (a) through (j) unti said position deviation value and said angular deviation value become smaller than predetermined allowable deviation values, respectively.

Claim 3

The method of claim 2, wherein the detection of said two-dimensional position of said second divided light beam in the step (g) is accomplished by detecting a gravity position of said second divided light beam on said second plane.

Claim 4

The method of claim 3, wherein the steps (i) and (j) comprise the steps of: (i-1) obtaining a position movement amount for reducing said position deviation; (j-1) moving at least one of said optical head and said object body on the basis of said position movement amount; (i-2) after the step (j-1), obtaining an angular movement amount for reducing said angular deviation; and (j-2) moving said object body on the basis of said angular movement amount.

Claim 5

The method of claim 4, further comprising the step of providing a position allowable deviation value and an angular allowable deviation value, wherein the steps (i-1) and (j-1) are repeated until said position deviation value become smaller than said position allowable deviation value, and wherein the steps (i-2) and (j-2) are repeated until said angular deviation value become smaller than said angular allowable deviation value.

Claim 6

The method of claim 5, wherein the step (i-2) and (j-2) further comprises the steps of: detecting and compensating said position deviation whenever the step (j-2) is executed.

Claim 7

The method of claim 6, further comprising the steps of: providing allowable deviation pairs of position allowable deviation values and angular allowable deviation values, and repeatedly executing the step (k) while selecting one of said allowable deviation pairs at each execution thereof.

Claim 8

The method of claim 7, wherein one of said allowable deviation pairs is selected in order of large value.

Claim 9

An automatic focusing device employed in an optical inspection system in which an object body supported with supporting means is inspected through an objective lens built in an optical head, said device comprising: (a) driving means coupled to at least one of said supporting means and said optical head, for varying relative positional and angular relations between said object body and said objective lens; (b) light beam generating means for generating a first light beam substantially being a parallel ray and for directing said first beam to said objective lens, wherein said first light beam incident on said object body through said objective lens is reflected at said object body to become a second light beam; (c) light dividing means for dividing said second light beam into first and second divided light beams after said second light beam returns through said objective lens; (d) an imaging lens positioned in an optical path of said first divided light beam; (e) one-dimensional photo-sensing means having a first light receiving surface positioned in a focal point of said imaging lens, for detecting a one-dimensional position of a light spot of said first divided light beam on said first light receiving surface; (f) positional deviation signal generating means for generating a positional deviation signal representing a positional deviation of an inspected plane in said object body from a focal point of said objective lens based upon an output signal of said one-dimensional photo-sensing means; (g) two-dimensional photo-sensing means having a second light receiving surface for receiving said second divided light beam, for detecting a two-dimensional position of said second divided light beam on said second light receiving surface; (h) angular deviation signal generating means for generating an angular deviation signal corresponding to an angular deviation of said inspected plane from a reference plane orthogonal to an optical axis of said objective lens based upon an output signal of said two-dimensional photo-sensing means; and (i) drive control means for generating a drive command signal as a function of said positional deviation signal and said angular deviation signal and for delivering said drive command signal to said driving means to enable said driving means so that said positional deviation and said angular deviation reach values smaller than predetermined allowable deviation values.

Claim 10

The device of claim 9, wherein said two-dimensional photo-sensing means is operable to detect a gravity of said second divided light beam on said second light receiving surface as said two-dimensional position of said second divided light beam.

Claim 11

The device of claim 10, wherein said drive control means comprises: (i-1) priority control means for conducting a positional control prior to an angular control; said positional control is a control for varying said relative positional relation; and said angular control is a control for varying said relative angular relation.

Claim 12

The device of claim 11, wherein said priority control means comprises: (i-1-1) means for providing a first command value corresponding to said positional deviation signal to said drive command signal to reduce said positional deviation to a value smaller than a predetermined allowable positional deviation value; and (i-1-2) means for providing a second command value corresponding to said angular deviation signal to said drive command signal to reduce said angular deviation to a value smaller than a predetermined allowable angular deviation value.

Claim 13

The device of claim 12, wherein said drive control means further comprises: (i-2) repetition means for enabling said priority control means repeatedly, to thereby repeat said positional control and said angular control.

Claim 14

The device of claim 13, wherein said drive control means further comprises: (i-3) means for reducing said allowable positional deviation value and said allowable angular deviation value by degrees in repetition of said positional control and said angular control.

Claim 15

The device of claim 14, wherein said angular deviation signal generating means further comprises: (h-1) means for repeatedly sampling an output signal of said two-dimensional photo-sensing means during said angular control to detect said angular deviation at each sampling; and (h-2) means for sequentially updating a value of said angular deviation signal as a function of said angular deviation detected by said means (h-1); and said drive conrtol means further comprises: (i-4) means for executing said position control in accordance with said value of said positional deviation signal whenever said means (h-2) updates said value of said angular deviation signal.

Claim 16

The device of claim 15, wherein said supporting means comprises: table means having a stage member on which said object body is held; and said driving means comprises: (a-1) first actuator means coupled to said table means for moving said table means together with said object body in a direction Z parallel to an optical axis of said first light beam; and (a-2) second actuator means provided in said table means for moving said stage member in said direction Z and for inclining said stage member together with said object body from an X-Y plane perpendicular to said direction Z.

Claim 17

The device of claim 16, wherein said table means further comprises: movable table member connected to said first actuator means and movable in said direction Z; a plurality of piezo electric elements arranged on said movable table member; and a plurality of pins coupled to said plurality of piezo electric elements, respectively, and on which said stage member is placed, wherein said plurality of piezo electric elements are operable to push up said plurality of pins in response to said drive command signal, respectively.

Claim 18

A movable table mechanism capable of holding an object body thereon for inspection of said object body with an inspection device, said movable table mechanism comprising: (a) a base table member supported on a supporting member; (b) a movable table member provided on said base table member and movable in lateral directions; (c) first through third piezo electric elements provided on said movable table member and arranged into a first triangle, wherein respective first ends of said first through third piezo electric elements are fixed to said movable table member in position; (d) first through third vertical pins provided on said movable table member and arranged into a second triangle on said movable table member, wherein respective bottom ends of said first through third vertical pins are coupled to respective second ends of said first through third piezo electric elements, respectively; (e) a stage member supported above said movable table member through said first through third vertical pins and having first through third concavities on a bottom surface of said stage member, wherein: said first through third concavities are arranged in a third triangle in congruence with said second triangle, respective top ends of said first through third vertical pins are inserted into said concavities, respectively; and said object body is placed on a top surface of said stage member; and (f) means for supplying electric voltages to said first through third piezo electric elements to expand or shrink said first through third piezo electric elements so that said movable table member is moved through coupling of said first through third vertical pins with said first through third piezo electric elements.

Claim 19

The movable table mechanism of claim 18, wherein said respective top ends of said first through third vertical pins and said first through third concavities are so shaped that; translational movement of said top end of said first pin in said first concavity is inhibited; translational movement of said top end of said second pin in said second concavity is restricted to linear movement parallel to said bottom surface of said stage member; and said top end of said third pin in said third concavity is movable in respective directions parallel to said bottom surface of said stage member.

Claim 20

The movable table mechanism of claim 19, wherein said top end of said first pin is shaped into a first cone; and said first concavity is shaped into a second cone of which apex angle is larger than an apex angle of said first cone.

Claim 21

The movable table mechanism of claim 20, wherein said top end of said second pin is shaped into a gable roof; and said second concavity is shaped into a groove longer than said gadle roof, said groove having a tapered bottom of which opening angle is larger than a vertex angle of said gable roof.

Claim 22

The movable table mechanism of claim 21, wherein said top end of said third pin has a spherical shape; and said third concavity has a cylindrical shape having a flat circular bottom of which diameter is larger than a diameter of said spherical shape.

Claim 23

The movable table mechanism of claim 22, further comprises: (g) first through third levers inserted between said respective second ends of said first through third piezo electric elements and said respective bottom ends of said first through third vertical pins to transmit displacement of said respective second ends of said first through third piezo electric elements to said first through third vertical pins in amplified strokes, respectively, wherein said displacement is caused by applying said electric voltages to said first through third piezo electric elements to expand or shrink said first through third piezo electric elements.

Claim 24

The movable table mechanism of claim 23, further comprises: (h) elevator means coupled to said base table member to move said base table member vertically.