Abstract
A light intensity fluctuation-insensitive projection objective wave aberration detection device and a detection method thereof, comprising a light source and illumination system, an object plane marking plate, an object plane displacement table, a tested projection objective, an image plane marking plate, a two-dimensional photosensor, an image plane displacement table and a control processing unit; the object plane marking plate and the image plane marking plate are provided with grating marks for shear interference test and marks for light intensity test, the shear interferograms and the light intensity information are simultaneously received through the two-dimensional photosensor, the light intensity fluctuation error corresponding to each phase-shifting interferogram is corrected through the light intensity information, improving the detection precision, reducing the complexity and the cost of the system, and improving the detection speed.
Claims
1. A light intensity fluctuation-insensitive projection objective wave aberration detection device, comprising a light source and illumination system (1), an object plane marking plate (2), an object plane displacement table (3), a tested projection objective (4), an image plane marking plate (5), a two-dimensional photosensor (6), an image plane displacement table (7), and a control processing unit (8), wherein the object plane marking plate (2), the object plane displacement table (3), the tested projection objective (4), the image plane marking plate (5), the two-dimensional photosensor (6), and the image plane displacement table (7) are sequentially arranged along direction of a spatially incoherent light output by the light source and illumination system (1); the object plane marking plate (2) is carried by the object plane displacement table (3), and the object plane marking plate (2) is located on the object plane of the tested projection objective (4); the image plane marking plate (5) and the two-dimensional photosensor (6) are carried and displaced by the image plane displacement table (7); the image plane marking plate (5) is located on the image plane of the tested projection objective (4); the two-dimensional photosensor (6) receives a light signal passing through the image plane marking plate (5), the light signal comprising an image side numerical aperture of the tested projection objective (4); the control processing unit (8) is respectively connected to the object plane displacement table (3), the image plane displacement table (7), and the two-dimensional photosensor (6); the object plane marking plate (2) comprises one or more pairs of object plane wave aberration test gratings with the shear diffraction directions being the X direction and the Y direction, respectively, and a pair of object plane light intensity test marks; the object plane wave aberration test gratings and the object plane light intensity test marks are positioned in the object side field-of-view and uniformly illuminated by the light source and illumination system (1), and the illumination numerical aperture of the object plane wave aberration test grating fills the object side numerical aperture range of the tested projection objective (4); the distance between the object plane wave aberration test grating pair is equal to the distance between the object plane light intensity test mark pair; the image plane marking plate (5) comprises one or more sets of image plane shear gratings matched with the object plane wave aberration test gratings and image plane light passing holes matched with the object plane light intensity test marks; the shear diffraction directions of the image plane shear grating are the X direction and Y direction; the object plane wave aberration test grating, the object plane light intensity test marks, the image plane shear grating and the image plane light passing hole are used as a set, the distance between the matched object plane wave aberration test grating and the object plane light intensity test mark and the distance between the corresponding image plane shear grating and the image plane light passing hole satisfy the multiplying power relationship of the tested projection objective so that as the object plane displacement table (3) and the image plane displacement table (7) are moved, the object plane wave aberration test grating and one object plane light intensity test mark in the X direction are respectively imaged to positions of the image plane shear grating and the image plane light passing hole through the tested projection objective (4), and the object plane wave aberration test grating and another object plane light intensity test mark in the Y direction are also be respectively imaged to positions of the image plane shear grating and the image plane light passing hole through the tested projection objective; the light imaged to the image plane shear grating generates multi-order diffraction to form shear interference fringes, and the shear diffraction direction is the shear direction of shear interference generated by the diffraction light of the image plane shear grating when the object plane wave aberration test grating is adopted; the light imaged to the image plane light passing hole forms an emergent light spot through the image plane light passing hole; and the interference fringe formed by the image plane shear grating and the emergent light spot through the image plane light passing hole are simultaneously received by the two-dimensional photosensor (6), and the receiving pixel areas are different.
2. The device of claim 1, wherein the object plane light intensity test mark is a grating, a light passing hole, or a light passing pattern area.
3. The device of claim 1, wherein the set of image plane shear gratings is a single two-dimensional grating or two mutually orthogonal one-dimensional gratings.
4. The device of claim 1, wherein the object plane marking plate (2) comprises a plurality of pairs of object plane wave aberration test gratings, and distances between different sets of image plane shear gratings comprised in the image plane marking plate (5) and distances between different pairs of object plane wave aberration test gratings satisfy the multiplying power relationship of the tested projection objective, so that the object plane wave aberration test grating and the image plane shear grating are in a conjugate position, and wave aberrations of a plurality of field-of-view points are measured simultaneously.
5. The device of claim 1, wherein the two-dimensional photosensor (6) is a CCD or CMOS camera with a global electronic shutter.
6. A method for detecting wave aberration using the device of claim 1, comprising: (1) moving the object plane displacement table (3), and moving the object plane wave aberration test grating with the shear diffraction direction being the X direction in the object plane marking plate (2) to the field-of-view point of the position of the tested projection objective (4); moving the image plane displacement table (7) so that the object plane wave aberration test grating is imaged on the image plane shear grating to form an interferogram in the X shear direction and received by the two-dimensional photo sensor (6) with the interferogram in the X shear direction of the object plane recorded as Ix.sub.0; at same time, the light intensity test mark on the object plane is imaged to the position of the image plane light passing hole to form an emergent light spot, which is received by another area of the two-dimensional photosensor (6), and the average value of the effective detection area of the emergent light spot is recorded as light intensity detection value Rx.sub.0; (2) moving the object plane displacement table (3) or the image plane displacement table (7) along the X direction to obtain a plurality of phase shift interferograms Ixo.sub.i in the X shear direction and light intensity detection values Rx.sub.i corresponding to each phase shift interferogram, wherein i=1, 2, 3, . . . N, wherein N is a positive integer; correcting the value of each phase shift interferogram Ixo.sub.i based on the light intensity detection values Rx.sub.i and Rx.sub.0 to obtain a corrected phase shift interferogram Ix.sub.i in the X shear direction; and then calculating the phase shift interferogram Ix.sub.0 and Ix.sub.i in the X shear direction to obtain a shear phase in the X direction; (3) moving the object plane displacement table (3), switching the object plane wave aberration test grating into a grating with the shear diffraction direction being the Y direction, when the image plane shear grating is a one-dimensional grating, switching the image plane shear grating at the same time, so that the interferogram Iy.sub.0 in the Y shear direction is received by the two-dimensional photosensor (6) and the light intensity detection value Ry.sub.0 is received in another area of the two-dimensional photosensor (6); (4) moving the object plane displacement table (3) or the image plane displacement table (7) along the Y direction to obtain a plurality of phase shift interferograms Iyo.sub.i in the Y shear direction and light intensity detection values Ry.sub.i corresponding to each phase shift interferogram, wherein i=1, 2, 3, . . . N, wherein N is a positive integer; correcting the value of each phase shift interferogram Iyo.sub.i based on the light intensity detection values Ry.sub.i and Ry.sub.0 to obtain a corrected phase shift interferogram Iy.sub.i in the Y shear direction; calculating the phase shift interferogram Iy.sub.0 and Iy.sub.i in the Y shear direction to obtain a shear phase in the Y direction; and (5) carrying out shear interference wavefront reconstruction by adopting shear phases in the X direction and the Y direction to obtain a wave aberration of the tested projection objective (4) at a tested field-of-view point.
7. The method of claim 6, wherein the interferogram in the X shear direction and the interferogram in the Y shear direction are single-channel interferograms or multi-channel interferograms, the single-channel interferogram is an interferogram corresponding to a field-of-view point, the multi-channel interferogram is divided into a plurality of mutually separated sub-interferogram regions, and each sub-interferogram is an interferogram corresponding to a field-of-view point.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) FIG. 1 shows the light intensity fluctuation-insensitive projection objective wave aberration detection device of the present invention.
(2) FIG. 2 shows the first embodiment of the object plane marking plate in the present invention.
(3) FIG. 3 shows the first embodiment of the image plane marking plate of the present invention.
(4) FIG. 4 shows the second embodiment of the image plane marking plate of the present invention.
(5) FIG. 5 shows the first view of the image received by the two-dimensional photosensor of the light intensity fluctuation-insensitive projection objective wave aberration detection device of the present invention.
(6) FIG. 6 shows the second embodiment of the object plane marking plate of the present invention.
(7) FIG. 7 shows the third embodiment of the image plane marking plate of the present invention.
(8) FIG. 8 shows the second view of the image received by the two-dimensional photosensor of the light intensity fluctuation-insensitive projection objective wave aberration detection device of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
(9) The present invention is further described below in conjunction with the accompanying drawings and embodiments, while the scope of the present invention should not be limited by them.
(10) As shown in FIG. 1, the light intensity fluctuation-insensitive projection objective wave aberration detection device of the present invention comprises a light source and illumination system 1, an object plane marking plate 2, an object plane displacement table 3, a tested projection objective 4, an image plane marking plate 5, a two-dimensional photosensor 6, an image plane displacement table 7, and a control processing unit 8; the light source and illumination system 1 output spatially incoherent light; the object plane marking plate 2 is located on the object plane of the tested projection objective 4; the object plane marking plate 2 is carried by the object plane displacement table 3 and displaced; the image plane marking plate 5 is located on the image plane of the tested projection objective 4; the two-dimensional photosensor 6 is located on the back side of the image plane marking plate 5 along the light transmission direction, and receives light signal passing through the image plane marking plate 5, the receiving range including the image side numerical aperture of the tested projection objective 4; the image plane marking plate 5 and the two-dimensional photosensor 6 are carried by the image plane displacement table 7 and displaced; the control processing unit 8 controls the operations of the object plane displacement table 3, the image plane displacement table 7, and two-dimensional photosensor 6 and processes the signal of the two-dimensional photosensor 6 to obtain the wave aberration of the tested projection objective 4; and the two-dimensional photosensor 6 is a CMOS camera using a global electronic shutter.
(11) As shown in FIG. 2, the first embodiment of the object plane marking plate 2 in the present invention comprises a pair of object plane wave aberration test gratings 2G_x and 2G_y with the shear diffraction directions being X direction and Y direction respectively, and a pair of object plane light intensity test marks 2R1 and 2R2; the object plane wave aberration test gratings 2G_x, 2G_y and the object plane light intensity test marks 2R1 and 2R2 are positioned in the object side field-of-view and uniformly illuminated by the light source and illumination system 1, and the illumination numerical aperture fills the object numerical aperture range of the tested projection objective 4 to be measured; the distance between the object plane wave aberration test grating pair 2G_x and 2G_y is equal to the distance between the object plane light intensity test mark pair 2R1 and 2R2; the object plane light intensity test marks 2R1 and 2R2 are gratings.
(12) As shown in FIG. 3, the first embodiment of the image plane marking plate 5 of the present invention comprises one image plane shear grating 5G used matched with the object plane wave aberration test gratings 2G_x and 2G_y in FIG. 2, and an image plane light passing hole 5R matched with the object plane light intensity test marks 2R1 and 2R2; the image plane shear grating 5G is one two-dimensional grating, with the shear diffraction directions being the X direction and the Y direction; the object plane wave aberration test grating, the object plane light intensity test marks, the image plane shear grating and the image plane light passing hole are used as a set; the distance between the object plane wave aberration test grating 2G_x and the object plane light intensity test mark 2R1 is equal to that of the object plane wave aberration test grating 2G_y and the object plane light intensity test mark 2R2, and the distance between the image plane shear grating 5G and the image plane light passing hole 5R satisfy the multiplying power relationship of the tested projection objective 4, so that as the object plane displacement table 3 and the image plane displacement table 7 are moved, the object plane wave aberration test grating 2G_x and one object plane light intensity test mark 2R1 in the X direction can be respectively imaged to positions of the image plane shear grating 5G and the image plane light passing hole 5R through the tested projection objective 4, and the object plane wave aberration test grating 2G_y and another object plane light intensity test mark 2R2 in the Y direction can also be respectively imaged to positions of the image plane shear grating 5G and the image plane light passing hole 5R through the tested projection objective; the light imaged to the image plane shear grating 5G generates multi-order diffraction to form shear interference fringes; when the object plane wave aberration test grating 2G_x is used, the shear diffraction direction of the image plane shear grating 5G is the X direction, and when the object plane wave aberration test grating 2G_y is used, the shear diffraction direction of the image plane shear grating 5G is Y direction, that is, the shear diffraction direction is the shear direction of shear interference generated by the diffracted light of the image plane shear grating 5G; the light that is imaged to the image plane light passing hole 5R, all passes through the image plane light passing hole 5R to form an emergent light spot.
(13) As shown in FIG. 4, the second embodiment of the image plane marking plate 5 of the present invention comprises a set of image plane shear gratings 5G_x and 5G_y matched with the object plane wave aberration test gratings 2G_x and 2G_y in FIG. 2, and image plane light passing holes 5R1 and 5R2 matched with the object plane light intensity test marks 2R1 and 2R2; the image plane shear gratings 5G_x, 5G_y are two orthogonal one-dimensional gratings, with the shear diffraction direction of the image plane shear grating 5G_x being the X direction, and the shear diffraction direction of the image plane shear grating 5G_y being the Y direction; the object plane wave aberration test grating, the object plane light intensity test marks, the image plane shear grating and the image plane light passing hole are used as a set; the distance between the object plane wave aberration test grating 2G_x and the object plane light intensity test mark 2R1 and the distance between the image plane shear grating 5G_x and the image plane light passing hole 5R1 satisfy the multiplying power relationship of the tested projection objective, the distance between the object plane wave aberration test grating 2G_y and the object plane light intensity test mark 2R2, and the distance between the image plane shear grating 5G_y and the image plane light passing hole 5R2 satisfy the multiplying power relationship of the tested projection objective, so that as the object plane displacement table 3 and the image plane displacement table 7 are moved, the object plane wave aberration test grating 2G_x and one object plane light intensity test mark 2R1 in the X direction can be respectively imaged to positions of the image plane shear grating 5G_x and the image plane light passing hole through the tested projection objective 4, and the object plane wave aberration test grating 2G_y and another object plane light intensity test mark 2R2 in the Y direction can also be respectively imaged to positions of the image plane shear grating 5G_y and the image plane light passing hole 5R2 through the tested projection objective 4; the light imaged to the image plane shear grating generates multi-order diffraction to form shear interference fringes, and the shear diffraction direction is the shear direction of shear interference generated by the diffraction light of the image plane shear grating when the object plane wave aberration test grating is adopted; in this embodiment, the object plane wave aberration test gratings 2G_x and 2G_y cannot be simultaneously imaged to the image plane shear gratings 5G_x and 5G_y respectively to avoid interference between interference fringes.
(14) The image received by the two-dimensional photosensor 6 of the projection objective wave aberration detection device of the present invention is shown in FIG. 5 when the embodiments of FIGS. 2 and 3 are used, and the interference fringes 61 formed by the image plane shear grating 5G and the emergent light spot 6R passing through the image plane light passing hole 5R are simultaneously received by the two-dimensional photosensor 6, and the receiving pixel areas are different.
(15) As shown in FIG. 6, the first embodiment of the object plane marking plate 2 of the present invention comprises a pair of object plane wave aberration test gratings 2G1_x, 2G1_y and 2G2_x, 2G2_y with shear diffraction directions in X direction and Y direction respectively, and a pair of object plane light intensity test marks 2R1 and 2R2; the object plane wave aberration test gratings 2G1_x, 2G1_y, 2G2_x, 2G2_y and the object plane light intensity test marks 2R1 and 2R2 are positioned in the object side field-of-view and uniformly illuminated by the light source and illumination system 1, and the illumination numerical aperture fills the object numerical aperture range of the tested projection objective 4 to be measured; the distance between the first object plane wave aberration test grating pair 2G1_x and 2G1_y, the distance between the second object plane wave aberration test grating pair 2G2_x and 2G2_y, the distance between the object plane light intensity test mark pair 2R1 and 2R2, is equal; and the object plane light intensity test marks 2R1 and 2R2 are gratings.
(16) As shown in FIG. 7, the third embodiment of the image plane marking plate 5 of the present invention comprises two sets of image plane shear gratings 5G1, 5G2 mated with the object plane wave aberration test gratings 2G1_x, 2G1_y, 2G2_x, and 2G2_y in FIG. 6 and image plane light passing hole 5R used in conjunction with object plane light intensity test marks 2R1, 2R2; the image plane shear gratings 5G1 and 5G2 are two-dimensional checkerboard gratings, and its shear diffraction directions are the X direction and the Y direction; As the object plane displacement table 3 and the image plane displacement table 7 are moved, the object plane wave aberration test grating 2G1_x and 2G2_x and one object plane light intensity test mark 2R1 in the X direction can be respectively imaged to positions of the image plane shear grating 5G1 and 5G2 and the image plane light passing hole 5R through the tested projection objective 4, and the object plane wave aberration test grating 2G1_y and 2G2_y and another object plane light intensity test mark 2R2 in the Y direction can also be respectively imaged to positions of the image plane shear grating 5G1 and 5G2 and the image plane light passing hole 5R through the tested projection objective 4; the light imaged to the image plane shear grating generate multi-order diffraction to form shear interference fringes, the shear diffraction direction is the shear direction of shear interference generated by the diffraction light of the image plane shear grating when the object plane wave aberration test grating is adopted.
(17) In the embodiments shown in FIGS. 6 and 7, the object plane marking plate 2 comprises a plurality of pairs of object plane wave aberration test gratings, and the image plane marking plate 5 includes different sets of image plane shear gratings 5G1, 5G2; the distance between the object plane wave aberration test gratings 2G1_x and 2G2_x is equal to the distance between object wave aberration test gratings 2G1_y and 2G2_y; the distance between image plane shear gratings 5G1 and 5G2 and the distance between the object plane wave aberration test gratings 2G1_x and 2G2_x satisfy the multiplying power relationship of the tested projection objective 4, so that the object wave aberration test grating and the image plane shear grating (image plane shear grating 5G1, 5G2 and object wave aberration test grating 2G1_x, 2G2_x, and the image plane shear gratings 5G1 and 5G2 and the object wave aberration test gratings 2G1_y, 2G2_y) can be in a conjugate position to measure wave aberrations at multiple field-of-view points at the same time.
(18) The image received by the two-dimensional photosensor 6 of the projection objective wave aberration detection device of the present invention is shown in FIG. 8 when the embodiments of FIGS. 6 and 7 are used, and the interference fringes 611 and 612 formed by the image plane shear grating 5G1 and 5G2 and the emergent light spot 6R passing through the image plane light passing hole 5R are simultaneously received by the two-dimensional photosensor 6, and the receiving pixel areas are different.
(19) The method for wave aberration detection using the light intensity fluctuation-insensitive projection objective wave aberration detection device of the present invention comprises the following steps:
(20) (1) moving the object plane displacement table 3, and moving the object plane wave aberration test grating with the shear diffraction direction being the X direction in the object plane marking plate 2 to the field-of-view point of the position of the tested projection objective 4; moving the image plane displacement table 7, so that the object plane wave aberration test grating is imaged on the image plane shear grating to form an interferogram in the X shear direction, which is received by the two-dimensional photosensor 6, and the interferogram in the X shear direction of the object plane recorded as Ix.sub.0; at the same time, the light intensity test mark on the object plane is imaged to the position of the image plane light passing hole to form an emergent light spot, which is received by another area of the two-dimensional photosensor 6, and the average value of the effective detection area of the emergent light spot is recorded as light intensity detection value Rx.sub.0;
(21) (2) moving the object plane displacement table 3 or the image plane displacement table 7 along the X direction to obtain a plurality of phase shift interferograms Ixo.sub.i in the X shear direction and light intensity detection values Rx.sub.i corresponding to each phase shift interferogram, wherein i=1, 2, 3, . . . N and N is a positive integer; correcting the value of each phase shift interferogram Ixo.sub.i based on the light intensity detection values Rx.sub.i and Rx.sub.0 to obtain a corrected phase shift interferogram Ix.sub.i in the X shear direction;
(22)
(23) and then calculating the phase shift interferogram Ix.sub.0 and Ix.sub.i in the X shear direction to obtain a shear phase in the X direction;
(24) (3) moving the object plane displacement table 3, switching the object plane wave aberration test grating into a grating with the shear diffraction direction being the Y direction, when the image plane shear grating is a one-dimensional grating, switching the image plane shear grating at the same time, so that the interferogram Iy.sub.0 in the Y shear direction is received by the two-dimensional photosensor 6, and meanwhile, the light intensity detection value Ry.sub.0 is received in the other area of the two-dimensional photosensor 6;
(25) (4) moving the object plane displacement table 3 or the image plane displacement table 7 along the Y direction to obtain a plurality of phase shift interferograms Iyo.sub.i in the Y shear direction and light intensity detection values Ry.sub.i corresponding to each phase shift interferogram, wherein i=1, 2, 3, . . . N and N is a positive integer; correcting the value of each phase shift interferogram Iyo.sub.i based on the light intensity detection values Ry.sub.i and Ry.sub.0 to obtain a corrected phase shift interferogram Iy.sub.i in the Y shear direction;
(26)
(27) and then calculating the phase shift interferogram Iy.sub.0 and Iy.sub.i in the Y shear direction to obtain a shear phase in the Y direction; and
(28) (5) carrying out shear interference wavefront reconstruction by adopting shear phases in the X direction and the Y direction to obtain a wave aberration of the tested projection objective 4 at a tested field-of-view point.
(29) The interferogram in the X shear direction and the interferogram in the Y shear direction are single-channel interferograms or multi-channel interferograms, the single-channel interferogram is an interferogram corresponding to a field-of-view point, the multi-channel interferogram is divided into a plurality of mutually separated sub-interferogram regions, and each sub-interferogram is an interferogram corresponding to a field-of-view point; in the embodiment of FIG. 5, 61 is a single-channel interferogram, and in the embodiment of FIGS. 8, 611 and 612 are multi-channel interferograms.
(30) The object plane wave aberration test grating, the image plane shear grating parameters, and the data processing method as mentioned above may be used in the embodiments of the present invention.
(31) The embodiment of the present invention has the following technical effects: the wave aberration detection device of the projection objective is insensitive to light intensity fluctuation of the light source, so that on one hand, the detection precision is improved, on the other hand, a complex dose control system is not needed, reducing complexity and cost of the system; the light integration time of each phase shift interferogram is shortened, improving the detection speed.
