Method and apparatus for setting a gap between first and second objects to a predetermined distance

Claim 1

A method for setting a gap between first and second objects, facing each other, to a predetermined distance, comprising the steps of: arranging a first one-dimensional diffraction grating on said first object, the first diffraction grating having parallel bars extending in a first direction, perpendicular to a first plane, to which a second plane inclines at a predetermined angle (α), said second plane being symmetrical to a third plane with respect to said first plane; arranging a second one-dimensional diffraction grating on said second object, the second diffraction grating having parallel bars extending in a second direction perpendicular to the first direction; irradiating said first diffraction grating with light beam emitted from a light source, the light beam having an optical axis present in the second plane, so that the light beam is diffracted and transmitted through the first diffraction grating, and first diffracted light beams are emerged from said first diffraction grating; transferring the first diffracted light beams to said second diffraction grating, so that the first diffracted light beams are diffracted and reflected by the second diffraction grating, and second diffracted light beams are emerged from said second diffraction grating; transferring the second diffracted light beams to said first diffraction grating, so that the second diffracted light beams are diffracted and transmitted through the first diffraction grating, third diffracted light beams are emerged from said first diffraction grating, some of the third diffracted light beams are transferred in the third plane, and the other third diffracted light beams are transferred in any planes other than the third plane; detecting one of the other third diffracted light beams; and adjusting a distance of the gap between said first and second objects, in accordance with an intensity of the detected diffracted light beam, and setting the gap to a predetermined distance.

Claim 2

A method for setting a gap between first and second objects, facing each other, to a predetermined distance, comprising the steps of: arranging a first one-dimensional diffraction grating on said first object, the first diffraction grating having parallel bars extending in a first direction, perpendicular to a first plane, to which a second plane inclines at a predetermined angle (α), said second plane being symmetrical to a third plane with respect to said first plane; arranging a second one-dimensional diffraction grating on said second object, the second diffraction grating having parallel bars extending in a second direction perpendicular to the first direction; irradiating said first diffraction grating with light beam emitted from a light source, the light beam having an optical axis present in the second plane, so that the light beam is diffracted and transmitted through the first diffraction grating, and first diffracted light beams are emerged from said first diffraction grating; transferring the first diffracted light beams to said second diffraction grating, so that the first diffracted light beams are diffracted and reflected by the second diffraction grating, and second diffracted light beams are emerged from said second diffraction grating; transferring the second diffracted light beams to said first diffraction grating, so that the second diffracted light beams are diffracted and transmitted through the first diffraction grating, third diffracted light beams are emerged from said first diffraction grating, some of the third diffracted light beams are transferred in the third plane, and the other third diffracted light beams are transferred in any planes other than the third plane; detecting one of the other third diffracted light beams; and adjusting a distance of the gap between said first and second objects, in accordance with an intensity of the detected diffracted light beam, and setting the gap to a predetermined distance.

Claim 4

The method according to cliam 1, wherein the angle (α) at which said first plane inclines to said second plane is 0°.

Claim 5

The method according to cliam 1, wherein the angle (α) at which said first plane inclines to said second plane is 0°.

Claim 14

A method for setting a gap between first and second objects, facing each other, to a predetermined distance, comprising the steps of: arranging a first one-dimensional diffraction grating on said first object, the first diffraction grating having parallel bars extending in a first direction perpendicular to a first plane, to which a second plane inclines at a predetermined angle (α), said second plane being symmetrical to a third plane with respect to said first plane; arranging a second two-dimensional diffraction grating on said second object, the second diffraction grating having cross-bars, one bar of cross-bars extending in a second direction perpendicular to the first direction wherein the pitches of the first diffraction grating and the pitches of the second diffraction grating in the second direction are equal to each other; irradiating said first diffraction grating with light beam emitted from a light source, the light beam having an optical axis present in the second plane, so that the light beam is diffracted and transmitted through the first diffraction grating, and first diffracted light beams are emerged from said first diffraction grating; transferring the first diffracted light beams to said second diffraction grating, so that the first diffracted light beams are diffracted and reflected by the second diffraction grating, and second diffracted light beams are emerged from said second diffraction grating; transferring the second diffracted light beams to said first diffraction grating, so that the second diffracted light beams are diffracted and transmitted through the first diffraction grating, third diffracted light beams are emerged from said first diffraction grating, some of the third diffracted light beams are transferred in the third plane, and the other third diffracted light beams are transferred in and planes other than the third plane; detecting one of the other third diffracted light beams; and adjusting a distance of the gap between said first and second objects, in accordance with an intensity of the detected diffracted light beam, and setting the gap to a predetermined distance.

Claim 15

A method for setting a gap between first and second objects, facing each other, to a predetermined distance, comprising the steps of: arranging a first one-dimensional diffraction grating on said first object, the first diffraction grating having parallel bars extending in a first direction perpendicular to a first plane, to which a second plane inclines at a predetermined angle (α), said second plane being symmetrical to a third plane with respect to said first plane; arranging a second two-dimensional diffraction grating on said second object, the second diffraction grating having cross-bars, one bar of cross-bars extending in a second direction perpendicular to the first direction wherein the pitches of the first diffraction grating and the pitches of the second diffraction grating in the second direction are equal to each other; irradiating said first diffraction grating with light beam emitted from a light source, the light beam having an optical axis present in the second plane, so that the light beam is diffracted and transmitted through the first diffraction grating, and first diffracted light beams are emerged from said first diffraction grating; transferring the first diffracted light beams to said second diffraction grating, so that the first diffracted light beams are diffracted and reflected by the second diffraction grating, and second diffracted light beams are emerged from said second diffraction grating; transferring the second diffracted light beams to said first diffraction grating, so that the second diffracted light beams are diffracted and transmitted through the first diffraction grating, third diffracted light beams are emerged from said first diffraction grating, some of the third diffracted light beams are transferred in the third plane, and the other third diffracted light beams are transferred in and planes other than the third plane; detecting one of the other third diffracted light beams; and adjusting a distance of the gap between said first and second objects, in accordance with an intensity of the detected diffracted light beam, and setting the gap to a predetermined distance.

Claim 17

The method according to cliam 10, wherein the angle (α) at which sasid first plane inclines to said second plane is 0°.

Claim 18

The method according to cliam 10, wherein the angle (α) at which sasid first plane inclines to said second plane is 0°.

Claim 25

The apparatus for setting a gap between first and second objects, facing each other, to a predetermined distance, comprising: a light source for emitting a light beam; a first one-dimensional diffraction grating which is arranged on said first object, the first diffraction grating having parallel bars extending in a first direction, perpendicular to a first plane, to which a second plane inclines at a predetermined angle (α), said second plane being symmetrical to a third plane with respect to said first plane, the first diffraction grating receiving the light beam present in the second plane, so that the light beam is diffracted and transmitted through the first diffraction grating, and first diffracted light beams are emerged from said first diffraction grating; a second one-dimensional diffraction grating which is arranged on said second object, the second diffraction grating having parallel bars extending in a second direction perpendicular to the first direction, the first diffracted light beams being transferred from the first diffraction grating to the second diffraction grating, so that the first diffracted light beams are diffracted and reflected by the second diffraction grating, second diffracted light beams are emerged from the second diffraction grating, and the second diffracted light beams from the second diffraction grating to the first diffraction grating, so that the second diffracted light beams are diffracted and transmitted through the first diffraction grating, third diffracted light beams are emerged from said first diffraction grating, some of the third diffracted light beams are transferred in the third plane, and the other third diffracted light beams are transferred in any planes other than the third planes; detecting means for detecting one of the other third diffracted light beams; and gap-adjusting means for adjusting the distance of the gap between said first and second objects, in accordance with the intensity of the detected diffracted light beam, and setting the gap to a predetermined distance.

Claim 26

The apparatus for setting a gap between first and second objects, facing each other, to a predetermined distance, comprising: a light source for emitting a light beam; a first one-dimensional diffraction grating which is arranged on said first object, the first diffraction grating having parallel bars extending in a first direction, perpendicular to a first plane, to which a second plane inclines at a predetermined angle (α), said second plane being symmetrical to a third plane with respect to said first plane, the first diffraction grating receiving the light beam present in the second plane, so that the light beam is diffracted and transmitted through the first diffraction grating, and first diffracted light beams are emerged from said first diffraction grating; a second one-dimensional diffraction grating which is arranged on said second object, the second diffraction grating having parallel bars extending in a second direction perpendicular to the first direction, the first diffracted light beams being transferred from the first diffraction grating to the second diffraction grating, so that the first diffracted light beams are diffracted and reflected by the second diffraction grating, second diffracted light beams are emerged from the second diffraction grating, and the second diffracted light beams from the second diffraction grating to the first diffraction grating, so that the second diffracted light beams are diffracted and transmitted through the first diffraction grating, third diffracted light beams are emerged from said first diffraction grating, some of the third diffracted light beams are transferred in the third plane, and the other third diffracted light beams are transferred in any planes other than the third planes; detecting means for detecting one of the other third diffracted light beams; and gap-adjusting means for adjusting the distance of the gap between said first and second objects, in accordance with the intensity of the detected diffracted light beam, and setting the gap to a predetermined distance.

Claim 36

The apparatus for setting a gap between first and second objects, facing each other, to a predetermined distance, comprising: a light source for emitting a light beam; a first one-dimensional diffraction grating which is arranged on said first object, the first diffraction grating having parallel bars extending in a first direction, perpendicular to e first plane, to which a second planes inclines at a predetermined angle (α), said second plane being symmetrical to a third plane with respect to said first plane, the first diffraction grating receiving the light beam which has an optical axis present in the second plane, so that the light beam is diffracted and transmitted through the first diffraction grating, and first diffracted light beams are emerged from said first diffraction grating; a second two-dimensional diffraction grating which is arranged on said second object, the second diffraction grating having cross-bars, one bar of cross-bars extending in a second direction perpendicular to the first direction, the first diffracted light beams being transferred from the first diffraction grating to the second diffraction grating, so that the first diffracted light beams are diffracted and reflected by the second diffraction grating, second diffracted light beams are emerged from the second diffraction grating, and the second diffracted grating to the first diffraction grating, so that the second diffracted light beams are diffracted and transmitted through the first diffraction grating, third diffracted light beams are emerged from said first diffraction grating, some of the third diffracted light beams are transferred in the third plane, and the other third diffracted light bems are transferred in any planes other than the third plane wherein the pitches of the first diffraction grating and the pitches of the second diffraction grating in the second direction are equal to each other; detecting means for detecting one of the other third diffracted light beams; and gap-adjusting means for adjusting a distance of a gap between said first and second objects, in accordance with an intensity of the detected diffracted light beam, and setting the gap to a predetermined distance.

Claim 37

The apparatus for setting a gap between first and second objects, facing each other, to a predetermined distance, comprising: a light source for emitting a light beam; a first one-dimensional diffraction grating which is arranged on said first object, the first diffraction grating having parallel bars extending in a first direction, perpendicular to e first plane, to which a second planes inclines at a predetermined angle (α), said second plane being symmetrical to a third plane with respect to said first plane, the first diffraction grating receiving the light beam which has an optical axis present in the second plane, so that the light beam is diffracted and transmitted through the first diffraction grating, and first diffracted light beams are emerged from said first diffraction grating; a second two-dimensional diffraction grating which is arranged on said second object, the second diffraction grating having cross-bars, one bar of cross-bars extending in a second direction perpendicular to the first direction, the first diffracted light beams being transferred from the first diffraction grating to the second diffraction grating, so that the first diffracted light beams are diffracted and reflected by the second diffraction grating, second diffracted light beams are emerged from the second diffraction grating, and the second diffracted grating to the first diffraction grating, so that the second diffracted light beams are diffracted and transmitted through the first diffraction grating, third diffracted light beams are emerged from said first diffraction grating, some of the third diffracted light beams are transferred in the third plane, and the other third diffracted light bems are transferred in any planes other than the third plane wherein the pitches of the first diffraction grating and the pitches of the second diffraction grating in the second direction are equal to each other; detecting means for detecting one of the other third diffracted light beams; and gap-adjusting means for adjusting a distance of a gap between said first and second objects, in accordance with an intensity of the detected diffracted light beam, and setting the gap to a predetermined distance.

Claim 49

A method for setting a gap between first and second objects, facing each other, to a predetermined distance, comprising the steps of: arranging two sets of first-type one-dimensional diffraction grating on said first object, the first-type diffraction grating having parallel bars extending in a first direction perpendicular to a first plane, to which a second plane inclines at a predetermined angle (α), said second plane being symmetrical to a third plane with respect to said first plane; arranging two sets of a second-type two-dimensional diffraction grating on said second object, the second-type diffraction grating having cross-bars, with one bar of said cross-bars extending in a second direction perpendicular to the first direction; irradiating said first-type diffraction gratings with light beam emitted from a light source, the light beam having an optical axis present in the second plane, so that the light beam is diffracted and transmitted through the first-type diffraction gratings, and first diffracted light beams are emerged from said first diffraction gratings; transferring the first diffracted light beams to said second-type diffraction gratings, so that the first diffracted light beams are diffracted and reflected by the second-type diffraction gratings, and second diffracted light beams are emerged from said second diffraction gratings; transferring the second diffracted light beams to said first-type diffraction gratings, so that the second diffracted light beams are diffracted and transmitted through the first-type diffraction gratings, third diffracted light beams are emerged from said first-type diffraction gratings, some of the third diffracted light beams are the intensities.

Claim 50

A method for setting a gap between first and second objects, facing each other, to a predetermined distance, comprising the steps of: arranging two sets of first-type one-dimensional diffraction grating on said first object, the first-type diffraction grating having parallel bars extending in a first direction perpendicular to a first plane, to which a second plane inclines at a predetermined angle (α), said second plane being symmetrical to a third plane with respect to said first plane; arranging two sets of a second-type two-dimensional diffraction grating on said second object, the second-type diffraction grating having cross-bars, with one bar of said cross-bars extending in a second direction perpendicular to the first direction; irradiating said first-type diffraction gratings with light beam emitted from a light source, the light beam having an optical axis present in the second plane, so that the light beam is diffracted and transmitted through the first-type diffraction gratings, and first diffracted light beams are emerged from said first diffraction gratings; transferring the first diffracted light beams to said second-type diffraction gratings, so that the first diffracted light beams are diffracted and reflected by the second-type diffraction gratings, and second diffracted light beams are emerged from said second diffraction gratings; transferring the second diffracted light beams to said first-type diffraction gratings, so that the second diffracted light beams are diffracted and transmitted through the first-type diffraction gratings, third diffracted light beams are emerged from said first-type diffraction gratings, some of the third diffracted light beams are the intensities.

Claim 51

The apparatus for setting a gap between first and second objects, facing each other, to a predetermined distance, comprising: a light source for emitting a light beam; a set of two, first-type one-dimensional diffraction gratings which are arranged on said first object, the first-type diffraction gratings having parallel bars extending in a first direction, perpendicular to a first plane, to which a second plane inclines at a predetermined angle (α), said second plane being symmetrical to a third plane with respect to said first plane, the first-type diffraction gratings receiving the light beam which has an optical axis present in the second plane, so that the light beam is diffracted and transmitted through the first-type diffraction gratings, and first diffracted light beams are emerged from said first-type diffraction gratings; a set of two second-type two-dimensional diffraction gratings which are arranged on said second object, the second-type diffraction gratings having cross-bars, with one bar of said cross-bars extending in a second direction perpendicular to the first direction, the first diffracted light beams being transferred from the first-type diffraction gratings to the second-type diffraction gratings, so that the first diffracted light beams are diffracted and reflected by the second-type diffraction gratings, second diffracted light beams are emerged from the second-type diffraction gratings, and the second diffracted light beams from the second-type diffraction gratings to the first-type diffraction gratings, so that the second diffracted light beams are diffracted and transmitted through the first-type diffraction gratings, third diffracted light beams are emerged from said first-type diffraction gratings, some of the third diffracted light beams are transferred in the third plane, and the other third diffracted light beams are transferred in and planes other than the third plane; detecting means for detecting one of the other third diffracted light beams; gap-adjusting means for adjusting a distance of a gap between said first and second objects, in accordance with an intensity of the detected diffracted light beam, and setting the gap to be a predetermined distance; and wherein if a distance between said two first diffraction gratings is given as u, a distance between said two second diffraction gratings is given as v, the diffraction pitch in an x direction of said first and second diffraction gratings is given as Px, and N is an arbitrary integer, u and v can be defined as: v=u+{(2N+1)/2}·P.sub.x said detecting means includes pickup means for separately picking up one of the other third diffracted light beams diffracted by one set of said first and second diffraction gratings, and one of the other third diffracted light beams diffracted by the other set of said first and second diffraction gratings, and said gap adjusting means includes calculation means for calculating a difference between intensities of the two diffracted light beams.

Claim 52

The apparatus for setting a gap between first and second objects, facing each other, to a predetermined distance, comprising: a light source for emitting a light beam; a set of two, first-type one-dimensional diffraction gratings which are arranged on said first object, the first-type diffraction gratings having parallel bars extending in a first direction, perpendicular to a first plane, to which a second plane inclines at a predetermined angle (α), said second plane being symmetrical to a third plane with respect to said first plane, the first-type diffraction gratings receiving the light beam which has an optical axis present in the second plane, so that the light beam is diffracted and transmitted through the first-type diffraction gratings, and first diffracted light beams are emerged from said first-type diffraction gratings; a set of two second-type two-dimensional diffraction gratings which are arranged on said second object, the second-type diffraction gratings having cross-bars, with one bar of said cross-bars extending in a second direction perpendicular to the first direction, the first diffracted light beams being transferred from the first-type diffraction gratings to the second-type diffraction gratings, so that the first diffracted light beams are diffracted and reflected by the second-type diffraction gratings, second diffracted light beams are emerged from the second-type diffraction gratings, and the second diffracted light beams from the second-type diffraction gratings to the first-type diffraction gratings, so that the second diffracted light beams are diffracted and transmitted through the first-type diffraction gratings, third diffracted light beams are emerged from said first-type diffraction gratings, some of the third diffracted light beams are transferred in the third plane, and the other third diffracted light beams are transferred in and planes other than the third plane; detecting means for detecting one of the other third diffracted light beams; gap-adjusting means for adjusting a distance of a gap between said first and second objects, in accordance with an intensity of the detected diffracted light beam, and setting the gap to be a predetermined distance; and wherein if a distance between said two first diffraction gratings is given as u, a distance between said two second diffraction gratings is given as v, the diffraction pitch in an x direction of said first and second diffraction gratings is given as Px, and N is an arbitrary integer, u and v can be defined as: v=u+{(2N+1)/2}·P.sub.x said detecting means includes pickup means for separately picking up one of the other third diffracted light beams diffracted by one set of said first and second diffraction gratings, and one of the other third diffracted light beams diffracted by the other set of said first and second diffraction gratings, and said gap adjusting means includes calculation means for calculating a difference between intensities of the two diffracted light beams.