CN110686620A - Measuring device and method for grating integration precision and measuring system for planar grating ruler - Google Patents
Measuring device and method for grating integration precision and measuring system for planar grating ruler Download PDFInfo
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Abstract
The invention discloses a measuring device and a method for grating integration precision and a measuring system for a planar grating ruler, wherein the measuring device comprises a light beam generating and receiving unit, a light beam adjusting unit and an integrated grating; the light beam adjusting unit comprises a parallel spectroscope and a reflection spectroscope; the reflection beam splitting prism comprises a transmission and reflection plane and a reflection plane; the integrated grating comprises a reference grating and a grating to be detected; the light beam generating and receiving unit emits light beams and determines the pitch angle, the deflection angle and the rotation angle of the reference grating and the grating to be detected; the parallel beam splitter divides the light beam into two parallel light beams; the transmitting and reflecting plane and the reflecting plane reflect the two parallel light beams to the reference grating and the grating to be measured and reflect the zero-order reflected light beam and the first-order diffracted light beam to the parallel spectroscope. The invention can provide two beams of parallel light with a long distance, thereby realizing the integration precision measurement of the large-space grating; the pitch angle, deflection angle and rotation angle of the reference grating and the grating to be detected can be detected simultaneously in a set of measuring device.
Description
Technical Field
The embodiment of the invention relates to the technical field of grating integration, in particular to a device and a method for measuring grating integration precision and a planar grating ruler measuring system.
Background
With the rapid development of the integrated circuit towards large scale and high integration, the alignment precision requirement of the photoetching machine is higher and higher, and correspondingly, the precision of acquiring the six-degree-of-freedom position information of the workpiece table and the mask table is improved.
The interferometer has high measurement precision, can reach nanometer level, and is used for measuring the positions of a workpiece table and a mask table in a photoetching system. However, the measurement accuracy of the current interferometer almost reaches the limit, meanwhile, the measurement accuracy of the interferometer is greatly influenced by the surrounding environment, the measurement repetition accuracy is not high (even if the environment is good, the measurement repetition accuracy exceeds 1nm), and the traditional interferometer measurement system is difficult to meet the requirement of further improving the alignment accuracy. Therefore, a high-precision and high-stability picometer measurement scheme is urgently needed.
In contrast, the optical path of the grating ruler measurement system can be very small, usually several millimeters, and the optical path is independent of the measurement range, so that the measurement precision of the grating ruler measurement system is insensitive to the environmental influence, and the grating ruler measurement system has the characteristics of high measurement stability, simple structure and easiness in miniaturization, and occupies an important place in the field of nano measurement. Interferometers are gradually replaced in a new generation of photoetching systems, and the tasks of high-precision and high-stability picometer precision measurement are undertaken.
Because a plurality of gratings are required to be spliced and integrated in the planar grating ruler measurement system, the grating splicing and integration precision is required to be controlled. In the prior art, the measurement method of the grating splicing precision only can accurately measure the condition that the gap between grating splicing seams is small, but cannot accurately measure the condition that the gap between grating splicing seams is large.
Disclosure of Invention
In view of this, embodiments of the present invention provide a device and a method for measuring grating integration accuracy, and a planar grating ruler measurement system, so as to solve the technical problem that accurate measurement cannot be performed on a condition that a grating splicing gap is large in the prior art.
In a first aspect, an embodiment of the present invention provides a device for measuring grating integration accuracy, including a light beam generating and receiving unit, a light beam adjusting unit, and an integrated grating;
the light beam adjusting unit comprises a parallel spectroscope and a reflection spectroscope, and the reflection spectroscope is positioned on one side of the parallel spectroscope, which is far away from the light beam generating and receiving unit; the reflection beam splitting prism comprises a transmission and reflection plane and a reflection plane;
the integrated grating comprises a reference grating and a grating to be detected;
the light beam generating and receiving unit is used for emitting light beams and receiving a first zero-order reflected light beam and a first-order diffracted light beam of the reference grating and a second zero-order reflected light beam and a second first-order diffracted light beam of the grating to be detected; determining a pitch angle and a deflection angle of the reference grating and the grating to be detected according to the first zero-order reflected beam and the second zero-order reflected beam, and determining a rotation angle of the reference grating and the grating to be detected according to the first-order diffracted beam and the second first-order diffracted beam;
the parallel spectroscope divides the light beam emitted by the light beam generating and receiving unit into two parallel light beams; transmitting a first zero-order reflected beam and a first-order diffracted beam of the reference grating, and a second zero-order reflected beam and a second first-order diffracted beam of the to-be-detected grating to the beam generating and receiving unit;
the transflective plane reflects two beams of the parallel light beams to the reference grating and the grating to be detected, and reflects a first zero-order reflected light beam generated by the reference grating and a second zero-order reflected light beam generated by the grating to be detected to the parallel spectroscope; the reflecting plane reflects the two parallel light beams to the reference grating and the grating to be detected, and reflects a first primary diffraction light beam generated by the reference grating and a second primary diffraction light beam generated by the grating to be detected to the parallel spectroscope.
Optionally, in the integration plane of the integrated grating, a distance between the grating to be measured and the reference grating is L1, where L1 is equal to or greater than 1mm and equal to or less than 999 mm.
Optionally, the two parallel light beams are reflected by the transflective plane and then vertically incident to the reference grating and the grating to be measured; and the two parallel light beams are reflected by the reflecting plane and then are incident to the reference grating and the grating to be detected at a littrow angle.
Optionally, the light beam adjusting unit further includes at least one angle fine-tuning unit, and the angle fine-tuning unit is located between the parallel beam splitter and the reflection beam splitter prism, and is configured to adjust the parallel light beam split by the parallel beam splitter.
Optionally, the light beam generating and receiving unit includes a light beam generating subunit, a light splitting subunit and a light beam receiving subunit;
the light beam generating subunit is used for emitting light beams;
the beam splitting subunit is used for transmitting the light beam emitted by the light beam generating subunit; reflecting the first zero-order reflected beam and the first-order diffracted beam of the reference grating, and the second zero-order reflected beam and the second first-order diffracted beam of the to-be-detected grating to the beam receiving subunit;
the light beam receiving subunit is used for determining the pitch angle and the deflection angle of the reference grating and the grating to be detected according to the first zero-order reflected light beam and the second zero-order reflected light beam; and determining the rotation angles of the reference grating and the grating to be detected according to the first-order diffracted beam and the second first-order diffracted beam.
Optionally, the spectroscopic subunit includes a half-mirror.
Optionally, the beam splitting subunit includes a polarization beam splitting prism and a quarter-wave plate, and the polarization beam splitting prism is located between the quarter-wave plate and the beam generating subunit;
the quarter-wave plate is used for transmitting the light beam emitted by the light beam generating subunit;
the polarization beam splitter prism is used for reflecting the first zero-order reflected beam and the first-order diffracted beam of the reference grating, and the second zero-order reflected beam and the second first-order diffracted beam of the to-be-measured grating to the beam receiving subunit.
Optionally, the beam receiving subunit includes an autocollimator.
Optionally, the light beam generating and receiving unit comprises a wavefront detection interferometer.
In a second aspect, an embodiment of the present invention provides a method for measuring grating integration accuracy, where the method for measuring grating integration accuracy provided in the first aspect is adopted, and the measuring apparatus includes a light beam generating and receiving unit, a light beam adjusting unit, and an integrated grating;
the light beam adjusting unit comprises a parallel spectroscope and a reflection spectroscope, and the reflection spectroscope is positioned on one side of the parallel spectroscope, which is far away from the light beam generating and receiving unit; the reflection beam splitting prism comprises a transmission and reflection plane and a reflection plane;
the integrated grating comprises a reference grating and a grating to be detected;
the measuring method comprises the following steps:
acquiring the pitch angle and deflection angle of the reference grating and the grating to be detected;
adjusting the grating to be measured to enable the grating to be measured to be parallel relative to the reference grating;
acquiring rotation angles of the reference grating and the grating to be detected;
and adjusting the grating to be detected to enable the difference of the rotation angle of the grating to be detected relative to the reference grating to be within a preset range.
In a third aspect, an embodiment of the present invention further provides a planar grating ruler measurement system, including the measurement apparatus for grating integration accuracy provided in the first aspect.
The device and the method for measuring the integration precision of the grating and the measuring system of the planar grating ruler provided by the embodiment of the invention have the advantages that the light beam adjusting unit comprises the parallel spectroscope and the reflection beam splitter prism, the parallel spectroscope divides the light beam emitted by the light beam generating and receiving unit into two parallel light beams, two parallel light beams with a long distance are ensured to be provided, and the integration precision of two gratings with a large distance is ensured to be measured; the reflection beam splitting prism comprises a transmission and reflection plane and can simultaneously detect the pitch angle, the deflection angle and the rotation angle of the reference grating and the grating to be detected in one set of measuring device through the transmission and reflection plane and the reflection plane, so that the high integration level of the measuring device is ensured.
Drawings
In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, a brief description is given below of the drawings used in describing the embodiments. It should be clear that the described figures are only views of some of the embodiments of the invention to be described, not all, and that for a person skilled in the art, other figures can be derived from these figures without inventive effort.
Fig. 1 is a schematic structural diagram of an integrated grating structure according to an embodiment of the present invention;
FIG. 2 is a schematic structural diagram of a measurement apparatus for measuring integration accuracy of a grating according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a measurement principle of a measurement apparatus for measuring integration accuracy of a grating according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of a measurement principle of another measurement apparatus for grating integration accuracy provided by an embodiment of the present invention;
FIG. 5 is a schematic diagram of a measurement principle of another measurement apparatus for measuring integration accuracy of a grating according to an embodiment of the present invention;
FIG. 6 is a schematic structural diagram of another measurement apparatus for measuring integration accuracy of a grating according to an embodiment of the present invention;
FIG. 7 is a schematic structural diagram of another measurement apparatus for measuring integration accuracy of a grating according to an embodiment of the present invention;
FIG. 8 is a schematic structural diagram of another measurement apparatus for measuring integration accuracy of a grating according to an embodiment of the present invention;
fig. 9 is a schematic structural diagram of a method for measuring grating integration accuracy according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be fully described by the detailed description with reference to the accompanying drawings in the embodiments of the present invention. It is obvious that the described embodiments are a part of the embodiments of the present invention, not all embodiments, and all other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without inventive efforts fall within the scope of the present invention.
In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be fully described by the detailed description with reference to the accompanying drawings in the embodiments of the present invention. It is obvious that the described embodiments are a part of the embodiments of the present invention, not all embodiments, and all other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without inventive efforts fall within the scope of the present invention.
According to the principle of grating diffraction, the displacement along the direction perpendicular to the grating lines can be obtained. In order to obtain a horizontal X, Y displacement, a two-dimensional plane grating scribed in two directions is required. The plane grating and the detection device are oppositely arranged, the detection device can detect the interference of X-direction + 1-1 order diffraction light and generate phase difference, and the interference of Y-direction + 1-1 order diffraction light and generate phase difference, so that X and Y displacement can be calculated. When the grating is moved in the Z-direction or the detecting means is moved in the Z-direction, the detecting means can detect the phase change, so that the Z-displacement can be calculated. Based on one plane grating, three degrees of freedom of X, Y and Z can be obtained, and in order to obtain multi-degree-of-freedom position information, a plurality of plane gratings and a plurality of detection devices are required to be combined together for realization.
The workpiece platform plane grating ruler measurement system needs to be combined with a plurality of gratings, and the scheme shown in fig. 1 is adopted, and the plane gratings 701 and 704 are installed on the grating installation plate 800; based on the motion measurement requirement of the workpiece table, the distance between the plane gratings along the Y direction is small, and is about millimeter magnitude; but are spaced widely in the X-direction, on the order of hundreds of millimeters.
One technical scheme in the prior art discloses a method for measuring the splicing precision of a high-precision large-aperture grating with five degrees of freedom, which can measure the pitch angle theta x, the deflection angle theta y and the rotation angle theta z of the grating to be spliced. The measurement has the characteristics of high precision, low coupling degree between the respective degrees of freedom, simple and convenient operation and the like. The technical scheme solves the problem that the measurement method of the splicing precision of the large-aperture grating is realized only by a method of increasing the light spot of the test beam when the distance between the reference grating and the grating to be measured is large because the test beam needs to be simultaneously incident on the reference grating and the test grating. However, the spot size of the light beam emitted by the laser is determined and cannot be infinite, so the technical scheme of the scheme mainly aims at the condition that the gap between the grating joints is small, and the problem of precision measurement of grating splicing with large space is not solved.
The other technical scheme of the prior art discloses an error detection method in a duplicated and spliced grating, which utilizes two beams of light of the zero order and the blazed diffraction order of the spliced grating to return to a wavefront measurement interferometer along the original path, and adjusts the positions and the angle postures of the two spliced gratings so as to minimize the diffraction wavefront difference of the two gratings. The scheme also mainly aims at the condition that the gap between the spliced gratings is small, and the problem of precision measurement of the splicing of the gratings with large spacing is not solved.
Based on the technical problem, the embodiment of the invention provides a device and a method for measuring grating integration precision and a system for measuring a planar grating ruler, wherein the device for measuring grating integration precision comprises a light beam generating and receiving unit, a light beam adjusting unit and an integrated grating; the light beam adjusting unit comprises a parallel spectroscope and a reflection beam splitter prism, and the reflection beam splitter prism is positioned on one side of the parallel spectroscope, which is far away from the light beam generating and receiving unit; the reflection beam splitting prism transmits the reflecting plane and reflects the plane; the integrated grating comprises a reference grating and a grating to be detected; the light beam generating and receiving unit is used for emitting light beams and receiving a first zero-order reflected light beam and a first-order diffracted light beam of the reference grating and a second zero-order reflected light beam and a second first-order diffracted light beam of the to-be-detected grating; determining the pitch angle and deflection angle of the reference grating and the grating to be detected according to the first zero-order reflected beam and the second zero-order reflected beam, and determining the rotation angle of the reference grating and the grating to be detected according to the first-order diffracted beam and the second first-order diffracted beam; the parallel spectroscope divides the light beam emitted by the light beam generating and receiving unit into two parallel light beams; transmitting the first zero-order reflected beam and the first-order diffracted beam of the reference grating, and the second zero-order reflected beam and the second first-order diffracted beam of the to-be-detected grating to the beam generating and receiving unit; the transflective plane reflects the two parallel light beams to the reference grating and the grating to be detected, and reflects a first zero-order reflected light beam generated by the reference grating and a second zero-order reflected light beam generated by the grating to be detected to the parallel spectroscope; the reflecting plane reflects the two parallel beams to the reference grating and the grating to be detected, and reflects the first-order diffraction beam generated by the reference grating and the second first-order diffraction beam generated by the grating to be detected to the parallel spectroscope. By adopting the technical scheme, the light beam emitted by the light beam generating and receiving unit is divided into two parallel light beams by the parallel spectroscope and is respectively incident to the reference grating and the grating to be detected, and for the condition that the distance between the reference grating and the grating to be detected is larger, the parameter of the parallel spectroscope only needs to be adjusted, the distance between the two parallel light beams divided by the parallel spectroscope is ensured to be larger, the light beam generating and receiving unit does not need to be adjusted, and the accurate measurement of the spliced grating with large distance can be ensured. Meanwhile, the reflection beam splitter prism comprises a transmission and reflection plane and can measure the pitch angle and deflection angle of the reference grating and the grating to be measured by the transmission and reflection plane and by using the original return characteristic of zero-order reflection beams of the reference grating and the grating to be measured; by the reflection plane, the rotation angle of the reference grating and the grating to be measured can be measured by applying the original return characteristic of the first-order diffracted beam, the pitch angle, the deflection angle and the rotation angle can be simultaneously detected in a measuring device on one side, and the measuring device is high in integration level.
The above is the core idea of the present invention, and the technical solution in the embodiment of the present invention will be clearly and completely described below with reference to the drawings in the embodiment of the present invention. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without any creative work belong to the protection scope of the present invention.
Fig. 2 is a schematic structural diagram of a measurement apparatus for grating integration accuracy according to an embodiment of the present invention, and fig. 3 is a schematic measurement principle diagram of the measurement apparatus for grating integration accuracy according to an embodiment of the present invention. It should be noted that the reflection beam splitter prism is a three-dimensional structure, and in order to clearly reflect the structure of the reflection beam splitter prism and the optical path conditions of the light beam on the transflective plane and the reflective plane respectively in the plane, the reflection beam splitter prism is schematically represented as the structure shown in fig. 3; meanwhile, the reference grating and the grating to be measured are arranged in a staggered manner in the direction vertical to the display plane and are overlapped in the display plane, and in order to clearly reflect the light path conditions of the reference grating and the grating to be measured in the display plane, the reference grating and the grating to be measured are represented as the staggered condition in the display plane; and aiming at the conditions of the transflective plane and the reflective plane, the reference grating and the grating to be measured are respectively shown in the display plane, and referring to the structural schematic diagram shown in fig. 2, it can be known that the transflective plane and the reflective plane correspond to the same set of reference grating and grating to be measured. Fig. 4 is a schematic diagram illustrating a principle of measurement of a transflective plane, and fig. 5 is a schematic diagram illustrating a principle of measurement of a reflective plane, as shown in fig. 2, fig. 3, fig. 4, and fig. 5, the apparatus for measuring integration accuracy of a grating according to an embodiment of the present invention may include: a light beam generating and receiving unit 1, a light beam adjusting unit 2 and an integrated grating 3;
the light beam adjusting unit 2 comprises a parallel spectroscope 400 and a reflection spectroscope 600, wherein the reflection spectroscope 600 is positioned at one side of the parallel spectroscope 400 far away from the light beam generating and receiving unit 1; the reflection splitting prism 600 includes a transflective plane 601 and a reflective plane 602;
the integrated grating 3 comprises a reference grating 701 and a grating 702 to be measured;
the light beam generating and receiving unit 1 is used for emitting light beams and receiving a first zero-order reflected light beam and a first-order diffracted light beam of the reference grating 701 and a second zero-order reflected light beam and a second first-order diffracted light beam of the to-be-detected grating 702; determining the pitch angle and the deflection angle of the reference grating 701 and the grating to be detected 702 according to the first zero-order reflected beam and the second zero-order reflected beam, and determining the rotation angle of the reference grating 701 and the grating to be detected 702 according to the first-order diffracted beam and the second first-order diffracted beam;
the parallel beam splitter 400 divides the light beam emitted by the light beam generating and receiving unit 1 into two parallel light beams; the first zero-order reflected beam and the first-order diffracted beam of the reference grating 701, and the second zero-order reflected beam and the second first-order diffracted beam of the to-be-measured grating 702 are transmitted to the beam generating and receiving unit 1;
the transflective plane 601 reflects the two parallel light beams to the reference grating 701 and the grating 702 to be measured, and reflects a first zero-order reflected light beam generated by the reference grating 701 and a second zero-order reflected light beam generated by the grating 702 to be measured to the parallel beam splitter 400; the reflection plane 602 reflects the two parallel light beams to the reference grating 701 and the grating to be measured 702, and reflects the first-order diffracted light beam generated by the reference grating 701 and the second first-order diffracted light beam generated by the grating to be measured 702 to the parallel beam splitter 400.
Continuing to refer to fig. 3 and 4, the light beam emitted by the light beam generating and receiving unit 1 is divided into two parallel light beams by the parallel beam splitter 400, the two parallel light beams vertically enter the reference grating 701 and the grating to be measured 702 after passing through the transflective plane 601, are reflected by the reference grating 701 and the grating to be measured 702, and then return to the transflective plane 601 in the original way of the first zero-order reflected light beam and the second zero-order reflected light beam vertically emitted from the reference grating 701 and the grating to be measured 702, are reflected by the transflective plane 601, then enter the light beam generating and receiving unit 1 after passing through the parallel beam splitter 400, and the light beam generating and receiving unit 1 determines the pitch angle and the deflection angle of the reference grating 701 and the grating to be measured 702 according to the received first zero-order reflected light beam and the second zero-order reflected light.
Specifically, the first zero-order reflected light beam emitted perpendicularly from the reference grating 701 can generate the position coordinate R on the light beam generating and receiving unit 1X1And RY1The second zero-order reflected light beam vertically emitted from the grating 701 to be measured can generate a position coordinate R on the light beam generating and receiving unit 1X2And RY2According to RX1And RX2The pitch angles of the reference grating 701 and the grating 702 to be detected, namely the angle of the grating rotating around the X axis, can be determined; according to RY1And RY2The deflection angles of the reference grating 701 and the grating 702 to be measured, that is, the rotation angle of the grating around the Y axis, can be determined, where the X axis can be defined as the direction perpendicular to the grid lines of the static grating, and the Y axis can be defined as the direction parallel to the grid lines of the static grating.
Continuing to refer to fig. 3 and 5, a light beam emitted by the light beam generating and receiving unit 1 is divided into two parallel light beams by the parallel beam splitter 400, the two parallel light beams are transmitted by the transflective plane 601 and then incident on the reflective plane 602, and are reflected by the reflective plane 602 and then incident on the reference grating 701 and the grating to be measured 702, the original paths of the first-order diffracted light beam and the second first-order diffracted light beam diffracted from the reference grating 701 and the grating to be measured 702 return to the reflective plane 602, and then are reflected by the reflective plane 602 and transmitted by the transflective plane 601 and then enter the light beam generating and receiving unit 1 through the parallel beam splitter 400, and the light beam generating and receiving unit 1 determines the rotation angles of the reference grating 701 and the grating to be measured 702 according to the received first-order diffracted light beam and second-order diffracted light beam.
Specifically, the first-order diffracted beam diffracted and emitted by the reference grating 701 can generate the position coordinate R on the beam generating and receiving unit 1Z1The second first order diffracted beam diffracted and emitted by the grating 702 to be measured can generate a position coordinate R on the beam generating and receiving unit 1Z2According to RZ1And RZ2The pitch angles of the reference grating 701 and the grating 702 to be measured, i.e. the angle of rotation of the grating around the Z-axis, which may be defined as the normal direction of the stationary grating, may be determined.
In summary, the device for measuring the integration accuracy of the grating provided by the embodiment of the invention divides the light beam emitted by the light beam generating and receiving unit into two parallel light beams through the parallel beam splitter, and the two parallel light beams are respectively incident on the reference grating and the grating to be measured, and for the case that the distance between the reference grating and the grating to be measured is large, only the parameter of the parallel beam splitter needs to be adjusted, so that the distance between the two parallel light beams divided by the parallel beam splitter is ensured to be large, the light beam generating and receiving unit does not need to be adjusted, and the accurate measurement of the spliced grating with large distance can be ensured. Meanwhile, the reflection beam splitter prism comprises a transmission and reflection plane and can measure the pitch angle and deflection angle of the reference grating and the grating to be measured by the transmission and reflection plane and by using the original return characteristic of zero-order reflection beams of the reference grating and the grating to be measured; by the reflection plane, the rotation angle of the reference grating and the grating to be detected can be measured by applying the original return characteristic of the first-order diffracted beam, so that the pitch angle, the deflection angle and the rotation angle of the reference grating and the grating to be detected can be simultaneously detected in a measuring device on one side, and the integration degree of the measuring device is high; and moreover, the pitch angle, deflection angle and rotation angle of the reference grating and the grating to be measured can be adjusted in real time, and the grating integration precision in the measuring device for ensuring the grating integration precision is high.
Optionally, in the integration plane of the integrated grating 3, a distance between the grating 702 to be measured and the reference grating 701 is L1, where L1 is greater than or equal to 1mm and less than or equal to 999 mm. In an exemplary embodiment of the present invention, in the measurement apparatus for measuring the integration accuracy of the grating, a parallel beam splitter 400 is creatively used, and the light beam emitted from the light beam generating and receiving unit can be split into two parallel beams by the parallel beam splitter 400; the size of the parallel spectroscope 400 is adjusted, the distance between two beams of parallel light can be adjusted, the integration precision of the integrated grating can be accurately measured under the condition that the distance between the grating to be measured 702 and the reference grating 701 is greater than or equal to 100mm, and the accurate measurement of the grating integration precision in the grating integration process with large space is realized.
Optionally, two parallel light beams are reflected by the transflective plane 601 and then vertically incident to the reference grating 701 and the grating 702 to be measured, so that the light beams reflected by the reference grating 701 and the grating 702 to be measured can be ensured to be vertically emergent and return to the transflective plane 601 along the original path, the pitch angle and the deflection angle of the reference grating and the grating to be measured can be measured without arranging other devices in the measuring device, and the measuring device for ensuring the grating integration precision is simple in structure.
Optionally, two parallel light beams are reflected by the reflection plane 602 and then are incident to the reference grating 701 and the grating 702 to be measured at a littrow angle, so that the light beams reflected by the reference grating 701 and the grating 702 to be measured are also ensured to return to the transflective plane 601 along the original path, the measurement of the pitch angle and the deflection angle of the reference grating and the grating to be measured can be realized without arranging other devices in the measurement device, and the measurement device for ensuring the grating integration precision is simple in structure. According to the grating equation: d (sin θ)in+sinθout) M λ, where d is the grating pitch, θinIs the angle of incidence of the grating, thetaoutIs the grating diffraction angle, m is the diffraction order, and λ is the wavelength of the incident light. Littrow angle refers to the grating incident angle θinEqual to first order grating diffraction angle thetaoutAngle of time thetaLThe grating equation is 2dsin thetaLWhen the light beam is incident on the reference grating 701 and the grating to be measured 702 at the littrow angle, the light is diffracted back along the light source direction.
Optionally, in the measurement apparatus for measuring integration accuracy of a grating provided in the embodiment of the present invention, the light beam adjustment unit 2 may further include at least one angle fine adjustment unit 500, and the angle fine adjustment unit 500 is located between the parallel beam splitter 400 and the reflection beam splitter 600, and is configured to adjust the parallel light beam split by the parallel beam splitter 400. Specifically, fig. 2, fig. 3, fig. 4, and fig. 5 illustrate the case where the light beam adjustment unit 2 includes one angle fine adjustment unit 500, fig. 6 illustrates the case where the light beam adjustment unit 2 includes two angle fine adjustment units 500, and the angle fine adjustment unit 500 is located between the parallel beam splitter 400 and the reflection beam splitter 600, and is used to calibrate the beam parallelism of the parallel beam splitter 400, ensure that the parallelism of two parallel light beams split by the parallel beam splitter 400 is good, and ensure that the measurement device of the whole grating integration precision has accurate measurement and small error.
Alternatively, with continuing reference to fig. 2, fig. 3, fig. 4, fig. 5 and fig. 6, in the measurement apparatus for measuring integration accuracy of a grating provided in the embodiment of the present invention, the light beam generating and receiving unit 1 may include a light beam generating subunit 100, a light splitting subunit 300 and a light beam receiving subunit 200;
the beam generating subunit 100 is used for emitting a light beam;
the sub-photon unit 300 is used for transmitting the light beam emitted by the light beam generating sub-unit 100; the first zero-order reflected beam and the first-order diffracted beam of the reference grating 701, and the second zero-order reflected beam and the second first-order diffracted beam of the to-be-measured grating 702 are reflected to the beam receiving subunit 200;
the light beam receiving subunit 200 is configured to determine pitch angles and deflection angles of the reference grating 701 and the grating 702 to be measured according to the first zero-order reflected light beam and the second zero-order reflected light beam; the rotation angles of the reference grating 701 and the grating to be measured 702 are determined from the first-order diffracted beam and the second-order diffracted beam.
Illustratively, the beam generation subunit 100 may be a laser source for emitting a laser beam of a single wavelength. The beam receiving subunit 200 may be an autocollimator, and the autocollimator receives the first zero-order reflected beam and the first-order diffracted beam of the reference grating 701 and the second zero-order reflected beam and the second first-order diffracted beam of the grating to be measured 702, respectively, and reads R of the reference grating 701X1、RY1And RZ1And is waiting forR of side grating 702X2、RY2And RZ2And acquiring the pitch angle, deflection angle and rotation angle of the reference grating 701 and the pitch angle, deflection angle and rotation angle of the grating 702 to be detected.
Optionally, as shown in fig. 2, fig. 3, fig. 4, fig. 5 and fig. 6, the beam splitting subunit 300 may be a half mirror, which is used to transmit the light beam emitted by the light beam generating subunit 100, and to conveniently reflect the first zero-order reflected light beam and the first-order diffracted light beam of the reference grating 701 and the second zero-order reflected light beam and the second first-order diffracted light beam of the grating to be measured 702 to the light beam receiving subunit 200.
Optionally, the splitting subunit 300 may further include a polarization splitting prism 301 and a quarter-wave plate 302, as shown in fig. 7, the polarization splitting prism 301 is located between the quarter-wave plate 302 and the beam generating subunit 100; the quarter-wave plate 302 is used for transmitting the light beam emitted by the light beam generating subunit 100; the polarization beam splitter prism 301 is configured to reflect the first zero-order reflected beam and the first-order diffracted beam of the reference grating 701, and the second zero-order reflected beam and the second first-order diffracted beam of the grating to be measured 702 to the beam receiving subunit 200.
Fig. 8 is a schematic structural diagram of another measurement apparatus for measuring integration accuracy of a grating according to an embodiment of the present invention, and as shown in fig. 8, in the measurement apparatus for measuring integration accuracy of a grating according to an embodiment of the present invention, the light beam generating and receiving unit 1 may be a wavefront measuring interferometer 101. The wavefront detection interferometer 101 detects the single-wavelength laser beam in the chequer kitchen, and detects the first zero-order reflected beam, the second zero-order reflected beam, the first-order diffracted beam and the second first-order diffracted beam returned by the reference grating 701 and the grating to be detected 702, and obtains the pitch angle, the deflection angle and the rotation angle of the grating to be detected 702 of the reference grating 701.
Fig. 9 is a schematic flow chart of a method for measuring integration accuracy of a grating according to an embodiment of the present invention, and an embodiment of the present invention further provides a method for measuring integration accuracy of a grating, where the method for measuring integration accuracy of a grating according to an embodiment of the present invention may be used as a device for measuring integration accuracy of a grating according to an embodiment of the present invention, and the device for measuring integration accuracy of a grating may include a light beam generating and receiving unit, a light beam adjusting unit, and an integrated grating;
the light beam adjusting unit comprises a parallel spectroscope and a reflection spectroscope, and the reflection spectroscope is positioned on one side of the parallel spectroscope, which is far away from the light beam generating and receiving unit; the reflection beam splitting prism comprises a transmission and reflection plane and a reflection plane; the integrated grating comprises a reference grating and a grating to be detected;
the method for measuring the grating integration precision provided by the embodiment of the invention can comprise the following steps:
and S110, acquiring the pitch angle and the deflection angle of the reference grating and the to-be-detected grating.
Illustratively, a light beam generated by the light beam generating and receiving unit is divided into two parallel light beams by the parallel beam splitter, the two parallel light beams are reflected by the transflective plane of the reflective beam splitter prism and then vertically incident to the reference grating and the grating to be measured, a first zero-order reflected light beam and a second zero-order reflected light beam generated after being reflected by the reference grating and the grating to be measured return to the light beam generating and receiving unit in original paths, and the light beam generating and receiving unit acquires the pitch angle and the deflection angle of the reference grating and the grating to be measured according to the received first zero-order reflected light beam and the received second zero-order reflected light beam.
Specifically, the first zero-order reflected light beam emitted perpendicularly from the reference grating 701 can generate the position coordinate R on the light beam generating and receiving unit 1X1And RY1The second zero-order reflected light beam vertically emitted from the grating 701 to be measured can generate a position coordinate R on the light beam generating and receiving unit 1X2And RY2According to RX1And RX2The pitch angles of the reference grating 701 and the grating 702 to be detected, namely the angle of the grating rotating around the X axis, can be determined; according to RY1And RY2The deflection angles of the reference grating 701 and the grating 702 to be measured, that is, the rotation angle of the grating around the Y axis, can be determined, where the X axis can be defined as the direction perpendicular to the grid lines of the static grating, and the Y axis can be defined as the direction parallel to the grid lines of the static grating.
And S120, adjusting the grating to be measured to enable the grating to be measured to be parallel relative to the reference grating.
The grating optical surface is limited by the processing precision of the gratingWith respect to the mechanical reference plane of the grating having RX，RYAngular deviation of the RX，RYThe deviation will affect the R between the gratingsZAnd detecting the angle. The reference grating is used as a mechanical grating reference surface, and whether the to-be-detected grating is parallel to the reference grating can be determined according to the pitch angle and the deflection angle of the reference grating and the pitch angle and the deflection angle of the to-be-detected grating. If the grating to be measured is not parallel to the reference grating, the grating to be measured can be adjusted to be parallel to the reference grating through the 6-degree-of-freedom adjusting device of the grating to be measured.
And S130, acquiring rotation angles of the reference grating and the grating to be measured.
Illustratively, after the grating to be measured is parallel to the reference grating, the light beam generated by the light beam generating and receiving unit is divided into two parallel light beams by the parallel beam splitter, the two parallel light beams are transmitted by the transmission and reflection plane of the reflection beam splitter prism and reflected by the reflection plane, and then enter the reference grating and the grating to be measured, and return to the light beam generating and receiving unit from the original paths of the first-order diffracted light beam and the second first-order diffracted light beam diffracted on the reference grating and the grating to be measured, and the light beam generating and receiving unit obtains the rotation angles of the reference grating and the grating to be measured according to the received first-order diffracted light beam and the received second-order diffracted light beam.
Specifically, the first-order diffracted light beam diffracted and emitted by the reference grating can generate a position coordinate R on the light beam generating and receiving unitZ1The second first-order diffraction beam diffracted and emitted by the grating to be detected can generate a position coordinate R on the beam generating and receiving unitZ2According to RZ1And RZ2The pitch angles of the reference grating and the grating to be measured, that is, the angle of rotation of the grating around the Z-axis, which may be defined as the normal direction of the stationary grating, may be determined.
S140, adjusting the grating to be measured to enable the difference of the rotation angle of the grating to be measured relative to the reference grating to be within a preset range.
The reference grating is used as a grating mechanical datum plane, and whether the rotation angle of the grating to be measured relative to the reference grating meets the precision requirement of the integrated grating can be determined according to the rotation angle of the reference grating and the rotation angle of the grating to be measured in the measurement process of the grating integration precision. If the rotation angle of the grating to be measured relative to the reference grating does not meet the precision requirement of the integrated grating, the rotation angle of the grating to be measured relative to the reference grating can be adjusted to be zero or adjusted to be within a required range through the 6-degree-of-freedom adjusting device of the grating to be measured.
According to the method for measuring the grating integration precision, provided by the embodiment of the invention, the grating to be measured is firstly adjusted to be relatively parallel to the reference grating, and then the rotation angle of the grating to be measured relative to the reference grating is adjusted to be within a preset range, so that the method for measuring the grating integration precision is ensured to be accurate. Meanwhile, the measurement method of the grating integration precision provided by the embodiment of the invention is finished by adopting the measurement device of the grating integration precision provided by the embodiment of the invention, has corresponding beneficial effects, and is not repeated herein.
It should be noted that the method for measuring the integration accuracy of the grating provided in the embodiment of the present invention is described by taking a mode of measuring and adjusting the pitch angle and the deflection angle of the reference grating and the grating to be measured, and then measuring and adjusting the rotation angle of the reference grating and the grating to be measured as an example. It can be understood that the pitch angle, the deflection angle and the rotation angle of the reference grating and the grating to be measured can be measured and adjusted simultaneously, so that the pitch angle, the deflection angle and the rotation angle can be accurately adjusted in real time.
In addition, if the zero-order reflected light beam and the first-order diffracted light beam of the reference grating and the grating to be detected do not need to be detected at the same time, the light shielding plate can be used for shielding the corresponding transflective plane or the reflecting plane.
Optionally, an embodiment of the present invention further provides a planar grating ruler measurement system, including the measurement apparatus for grating integration accuracy provided in the embodiment of the present invention, which has corresponding functions and beneficial effects, and is not described herein again.
It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious modifications, rearrangements, combinations and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.
Claims (11)
1. A device for measuring the integration accuracy of a grating, comprising: the device comprises a light beam generating and receiving unit, a light beam adjusting unit and an integrated grating;
the light beam adjusting unit comprises a parallel spectroscope and a reflection spectroscope, and the reflection spectroscope is positioned on one side of the parallel spectroscope, which is far away from the light beam generating and receiving unit; the reflection beam splitting prism comprises a transmission and reflection plane and a reflection plane;
the integrated grating comprises a reference grating and a grating to be detected;
the light beam generating and receiving unit is used for emitting light beams and receiving a first zero-order reflected light beam and a first-order diffracted light beam of the reference grating and a second zero-order reflected light beam and a second first-order diffracted light beam of the grating to be detected; determining a pitch angle and a deflection angle of the reference grating and the grating to be detected according to the first zero-order reflected beam and the second zero-order reflected beam, and determining a rotation angle of the reference grating and the grating to be detected according to the first-order diffracted beam and the second first-order diffracted beam;
the parallel spectroscope divides the light beam emitted by the light beam generating and receiving unit into two parallel light beams; transmitting a first zero-order reflected beam and a first-order diffracted beam of the reference grating, and a second zero-order reflected beam and a second first-order diffracted beam of the to-be-detected grating to the beam generating and receiving unit;
the transflective plane reflects two beams of the parallel light beams to the reference grating and the grating to be detected, and reflects a first zero-order reflected light beam generated by the reference grating and a second zero-order reflected light beam generated by the grating to be detected to the parallel spectroscope; the reflecting plane reflects the two parallel light beams to the reference grating and the grating to be detected, and reflects a first primary diffraction light beam generated by the reference grating and a second primary diffraction light beam generated by the grating to be detected to the parallel spectroscope.
2. The measurement device according to claim 1, wherein the distance between the grating under test and the reference grating in the integration plane of the integrated grating is L1, wherein L1 999mm is 1 mm.
3. The measuring device of claim 1, wherein two of the parallel light beams are reflected by the transflective plane and then vertically incident to the reference grating and the grating to be measured; and the two parallel light beams are reflected by the reflecting plane and then are incident to the reference grating and the grating to be detected at a littrow angle.
4. The measuring apparatus according to claim 1, wherein the beam adjusting unit further comprises at least one angle fine-tuning unit, which is located between the parallel beam splitter and the reflection beam splitter prism, and is configured to adjust the parallel beam split by the parallel beam splitter.
5. The measuring device of claim 1, wherein the beam generating and receiving unit comprises a beam generating subunit, a beam splitting subunit, and a beam receiving subunit;
the light beam generating subunit is used for emitting light beams;
the beam splitting subunit is used for transmitting the light beam emitted by the light beam generating subunit; reflecting the first zero-order reflected beam and the first-order diffracted beam of the reference grating, and the second zero-order reflected beam and the second first-order diffracted beam of the to-be-detected grating to the beam receiving subunit;
the light beam receiving subunit is used for determining the pitch angle and the deflection angle of the reference grating and the grating to be detected according to the first zero-order reflected light beam and the second zero-order reflected light beam; and determining the rotation angles of the reference grating and the grating to be detected according to the first-order diffracted beam and the second first-order diffracted beam.
6. The measurement device of claim 5, wherein the photonic splitting unit comprises a half-mirror.
7. The measurement device of claim 5, the beam splitting sub-unit comprising a polarization beam splitting prism and a quarter wave plate, the polarization beam splitting prism being located between the quarter wave plate and the beam generating sub-unit;
the quarter-wave plate is used for transmitting the light beam emitted by the light beam generating subunit;
the polarization beam splitter prism is used for reflecting the first zero-order reflected beam and the first-order diffracted beam of the reference grating, and the second zero-order reflected beam and the second first-order diffracted beam of the to-be-measured grating to the beam receiving subunit.
8. A measuring device according to claim 6, wherein the beam receiving subunit comprises an autocollimator.
9. A measuring device according to claim 1, wherein the beam generating and receiving unit comprises a wavefront-sensing interferometer.
10. A method for measuring the integration accuracy of a grating, which uses the device for measuring the integration accuracy of a grating according to any one of claims 1 to 9, wherein the device for measuring comprises a light beam generating and receiving unit, a light beam adjusting unit and an integrated grating;
the light beam adjusting unit comprises a parallel spectroscope and a reflection spectroscope, and the reflection spectroscope is positioned on one side of the parallel spectroscope, which is far away from the light beam generating and receiving unit; the reflection beam splitting prism comprises a transmission and reflection plane and a reflection plane;
the integrated grating comprises a reference grating and a grating to be detected;
the measuring method comprises the following steps:
acquiring the pitch angle and deflection angle of the reference grating and the grating to be detected;
adjusting the grating to be measured to enable the grating to be measured to be parallel relative to the reference grating;
acquiring rotation angles of the reference grating and the grating to be detected;
and adjusting the grating to be detected to enable the difference of the rotation angle of the grating to be detected relative to the reference grating to be within a preset range.
11. A planar grating scale measuring system comprising the grating integrated accuracy measuring apparatus according to any one of claims 1 to 9.
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