DE10349977A1 - Interferometer set-up e.g. for operating an interferometer, has radiation reflector connected and along measuring section in measuring direction is adjustable linearly, for determining measuring distance - Google Patents

Abstract

The interferometer has a radiation reflector connected and along measuring section in a measuring direction is adjustable linearly, for determining a measuring distance. The interferometer has a phase regulator connected in order to determine an optical phase measured value along the measuring section. A sound generator and a sound receiver having a second phase regulator connected, in order to determine an acoustic phase measured value. The outputs are connected from the handed over phase measured values and a correction value for the compensation of environmental influences during the optical. An independent claim is included for a method for the interferometer arrangement.

Description

The The present invention relates to an interferometer arrangement as well a method for operating an interferometer arrangement.

at length measurements by means of optical interferometer serves as measuring standard or material measure the wavelength the laser radiation used in air. This is hereafter as Light wavelength designated. The wavelength of light depends on certain environmental parameters, such as temperature, the pressure, the humidity and the concrete gas composition. For one correct length measurement is therefore the knowledge of the correct wavelength of light or a compensation of environmental influences during the measurement necessary.

In a first variant of interferometric length measuring are the various environmental parameters by means of suitable sensors he summarizes and thus determines a corrected or effective wavelength of light. This is usually a suitable correction function table available, which realized for example by software is. As part of such an approach is using the interferometer first an optical phase measured along the measuring path determined by the multiplication of the phase measurement value with the effective wavelength of light results in a known manner, the desired measured variable in the form of a measuring distance.

Around to determine the corrected or effective wavelength of light, is with a pressure sensor of air pressure and with one or more temperature sensors the mean air temperature in the vicinity of the measuring section determined. On the basis of the various sensor measured values can be with the help of the so-called. Noble formula determine a correction factor or correction value. The corrected or effective light wavelength is finally obtained by the multiplication of the vacuum wavelength with the correction value.

adversely At this procedure is that the different parameters regarding the Ambient conditions only at discrete points and only in nearby the optical measuring axis are determined. The exact course of this Parameters along the measuring axis is therefore only approximated, from which again inaccuracies in the determination of the effective wavelength of light and so with the actual length measurement result. In addition, the different sensors in the Usually have significant response times, so that possibly occurring short-term fluctuations of the parameters along the measuring axis also can not be detected correctly. Because of these shortcomings is the accuracy of the interferometric length measurement in air in this View variant as limited.

In an alternative interferometric measurement variant - hereinafter referred to as multi-wavelength interferometry - can be carried out by the use of multiple wavelengths, a correction of the vacuum wavelength. For this purpose, the dispersion behavior of air is used for correction ver. For example, let such methods on the US 5,404,222 or on the US 5,764,362 refer to the corresponding procedures in detail.

When disadvantageous in this variant environmentally compensated, interferometric Measurement method is due to the relatively large resulting effort the use of two high-precision laser light sources. Furthermore, there is always a certain measurement uncertainty in the required Determination of the dispersion behavior of air to be considered, since the exploited dispersion effect is very low.

A third possibility for correcting the wavelength of light in interferometric measuring methods is finally from the US 6,501,550 become known, which provides an acousto-optical interferometer arrangement for this purpose. With the aid of a sound transmitter and a sound receiver, the sound transit time along the measurement axis is determined and the speed of sound is determined by linking the measured sound transit time to the position known via the optical interferometer measurement. Since the speed of sound in turn depends on the prevailing ambient conditions in a known manner, a current average air temperature along the measuring axis can be determined via a corresponding correction function. The air temperature determined in this way then again serves as the input variable for the method already described for determining the mean wavelength of light by means of the Noble formula, etc. An advantage of this method is that the sound velocity averaged along the measuring axis is used as the measured quantity entering the correction. This can also be compensated for any fluctuations in the temperature along the measuring axis.

adversely However, here is that the speed of sound only too discrete times and thus also possible temporal variations the air temperature are only partially or only inaccurately detected.

The object of the present invention is to specify an interferometer arrangement and a method for its operation, via which an improved measuring accuracy is ensured. In particular, any fluctuations in the environmental conditions should be recorded as precisely as possible and compensated appropriately.

These Task is solved by an interferometer arrangement having the features of the claim 1.

advantageous embodiments the interferometer arrangement according to the invention arise from the measures in the dependent of claim 1 claims listed are.

Further the specified task is solved by a method for operating an interferometer with the Features of claim 17.

advantageous embodiments the method according to the invention arise from the measures in the dependent of claim 17 claims listed are.

According to the invention will now a conventional one optical interferometric length measurement and the possible out of it Determination of an optical phase measurement value with an additional determination an acoustic phase measurement combined to a high-precision correction the wavelength of light make. The determination of the acoustic phase measured value takes place via an acoustic signal Measurement setup by means of a suitable arrangement with at least one Sound transmitter, at least one sound receiver and possibly a sound reflector. The determination of the two phase measured values is carried out with the help of suitable Phase determination units made simultaneously along the measuring section. Over a Subsequent correction unit, the determined phase measured values are such further processed that about it a correction value to compensate for environmental influences the optical position determination is determined. On the determined correction value in turn can be corrected, the light wavelength or directly a corrected measuring distance can be determined.

at This approach is the different dependence of the optical and acoustic wavelengths exploited by the environmental conditions. Depending on the currently prevailing Ambient conditions give way to the determined, uncorrected acoustic and optical measuring distances by different amounts of difference from each other from. The respective difference or the ratio of these variables is thus a measure of the change of optical and acoustic wavelengths due to the influence of Environmental conditions and therefore can be used to correct the environmental conditions and the determination of a corrected wavelength of light used become.

In Regarding the arrangement and design of the sound transmitter, sound receiver and If necessary, the sound reflectors are within the scope of the present invention a number of different possibilities.

Especially advantageous the present invention in conjunction with an as xy-table use trained measuring object whose position is highly accurate too determine is. Corresponding measuring applications can be found approximately in Lithography systems for semiconductor fabrication such as e.g. in wafer steppers or wafer scanners.

Opposite the Initially discussed multi-wavelength interferometry is as To perform an advantage that only a single laser light source is needed. At the stabilization of the laser light source used are here significantly lower requirements than with multi-wavelength methods to deliver. Furthermore, the effort in terms of optical and acoustic phase measurement over the complex Differential phase detection in multi-wavelength interferometry clearly lower. Furthermore, it must be stated that the invention used Difference between the optical and acoustic path lengths or Measuring distances significantly stronger depends on the environmental conditions as the phase difference caused by the dispersion, the in multi-wavelength interferometry exploited for environmental compensation. As a result results a much more accurate determination of the correction value for the light wavelength.

When advantage over the known acousto-optical compensation variant is to be mentioned that in principle the measurement or determination of the acoustic phase measured value clearly more exactly possible is as a measurement of the speed of sound. It should also be mentioned that in the context of the present invention, the phase measurements continuously possible and thus a correction value is quasi-continuously available. As already mentioned, is according to the state the technique a determination of the sound transit time and thus the speed of sound provided only at discrete times, which then also from the to be determined correction values only in the corresponding discrete temporal Grid available stands.

Further Advantages and details of the present invention will become apparent from the following description of exemplary embodiments with reference to FIG enclosed figures.

there shows

1 a schematic block diagram of a first embodiment of the interferometer according to the invention;

2 a schematic block diagram of a second embodiment of the interferometer arrangement according to the invention;

3a - 3e in each case in a highly schematic form, a further variant of the interferometer arrangement according to the invention;

4a - 4c each an example of the use of inventive interferometer on an xy-table.

Based on the illustration in 1 Let a first embodiment of the interferometer arrangement according to the invention and the method according to the invention are explained in principle. It should be noted that the illustration in 1 is highly schematic and is intended only to describe the basic principles of the invention. On the basis of these considerations, the most varied variants are available for the specific embodiment, which will be explained in the course of the further description.

The interferometer arrangement according to the invention essentially comprises a known optical interferometer, which in the lower part of the 1 via the function block 10 is indicated schematically, and an acoustic measurement structure, which in the upper part of the illustration by the function block 20 is illustrated. With the help of the interferometer arrangement, the position of the object to be measured 30 be determined, which is linearly displaceable in the measuring direction x. The relative position determination is carried out here in a known manner with respect to any desired reference point along the measurement path.

In practice, these are the optical interferometer 10 as well as the acoustic function block 20 or measurement setup arranged so that the in 1 spatially separated measuring axes MA coincide, ie there are therefore only a single measuring axis MA of the entire interferometer.

The optical interferometer 10 is formed in a known manner, the representation of details was therefore omitted in this context. It includes, for example, a stationarily arranged laser light source, the emitted beam bundles are split into a measuring and reference beam, the measuring beam in the direction of the measured object 30 propagated and there by one with the measurement object 30 connected radiation reflector 11 is reflected back again. After the reunification with the reference beam, the interfering measuring and reference beams pass onto a detector arrangement, which in the case of the relative movement of the measuring object 30 resulting signal detected. The detector arrangement is on the side of the optical interferometer 10 a first phase determination unit 12 downstream, which has an optical phase measured value P _opt with respect to the position of the measurement object 30 along the measuring section delivers. The thus generated optical phase measured value P _{op t} is a downstream correction unit 40 whose function is explained below.

details the beam path guide and the various components of the optical interferometer were therefore not shown because in this regard a Range of different embodiments come into consideration.

The acoustic function block 20 In the illustrated example, the interferometer arrangement according to the invention essentially comprises a sound transmitter 21 and a sound receiver 22 , The sound transmitter 21 is due to the sinusoidal signal of a frequency generator 23 powered by an amplifier 24 is still suitably reinforced. As a sound transmitter 21 For example, suitable commercially available collimating ultrasonic transducers can be used which emit sound waves in the desired emission direction with as little divergence as possible. Such emission characteristics reduce the system sensitivity to resulting interference phenomena resulting from the reflection of sound waves on objects adjacent to the measurement axis MA. The frequency of the sound waves generated are preferably in the near ultrasonic range, for example in the range 25kHz - 100kHz. Such a frequency selection allows a determination of the acoustic path length or acoustic measuring distance L _{a k} with high resolution due to the low sound wavelength. Furthermore, good collimability of the sound waves is ensured at the same time only low attenuation along the measuring section.

With the movable measurement object 30 connected in the present example is a sound receiver 22 that detects the emitted sound waves. For example, as a sound receiver 22 commercially available microphones or suitable frequency-matched sound receiver units are used.

Preferably, as already indicated above, the sound transmitter 21 and the sound receiver 22 to be arranged so that the sound wave to be detected moves as close to the measuring axis MA or possibly coincides with it.

The from the sound receiver 22 Detected sound wave is through the downstream amplifier 25 amplified and a second phase determination unit 26 fed. The phase determination unit 26 Furthermore, the sinusoidal Anre signal for the sound transmitter 21 supplied, so that with the help of the second phase determination unit 26 an acoustic phase measured value P _{a k} can be determined and on the output side for further processing also to the already mentioned above correction unit 40 is handed over.

About the correction unit 40 With the aid of the transferred optical and acoustic phase measured values P _opt , P _ak, first of all the determination of a correction _value K _opt for compensation of environmental influences in the optical position determination takes place. With the aid of the correction _value K _opt , it is possible to use the correction unit 40 with respect to the environmental influences corrected light wavelength λ _{opt, korr} determine. Λ _opt from the corrected light _{wavelength, corr} the determination of the actual measured quantity in the form of the corrected measurement distance L _corr. The corrected measured distance L can then be reused as output under unterschiedlichster control tasks _corr. Alternatively, the corrected measurement distance L can _opt with the aid of the correction value K determined directly _corr be determined.

It will now be explained how according to the invention from the simultaneously measured quantities, ie the optical and acoustic phase measured values P _opt , P _{a k} on the correction unit 40 A suitable for the compensation of environmental influences correction value K _opt and in turn determining the corrected light wavelength λ _{opt, corr} and / or can be carried out to determine the corrected measurement distance L _corr.

As already indicated at the outset, the present invention makes use of the fact that both the actual optical and acoustic wavelengths - hereinafter referred to in this context as a light wavelength λ _opt and a sound wavelength λ _ak - are known in each case from the prevailing environmental parameters how temperature, pressure, humidity and gas composition depends. However, the dependencies on these parameters are very different for the light wavelength λ _{op t} and the sound wavelength λ _ak . Due to the different dependencies of the light wavelength λ _opt and the sound wavelength λ _{a k} of the various environmental parameters _, the deviation of the optical and acoustic measurement distances L _opt , L _ak to be determined by multiplying the phase measured value and wavelength is a measure of the change in wavelengths due to the environmental conditions , The relative deviation or the ratio of two sizes - optical measuring distance, L _opt, acoustic measuring distance Lak - can therefore according to the invention for determining _opt a correction value K, and in turn for the correction of the light wavelength λ _{o pt} or for determining a corrected measurement distance L _corr used become.

In one possible embodiment of the method according to the invention, as already mentioned, an optical phase measured value P _opt and an acoustic phase measured value P _{ak are} simultaneously determined. From the measured variable P _opt , an uncorrected optical measuring distance L _{opt is} determined by multiplication with the known uncorrected light wavelength λ _{opt of} the light source used, L _opt = P _opt · λ _opt . Analogously, the determination of an uncorrected acoustic measuring distance L _{a k} via the multiplication of the measured variable P _ak with the likewise known uncorrected acoustic wavelength λ _ak , ie L _{op t} = P _{op t} · λ _{op t} . From the variables thus determined, ie the uncorrected acoustic and optical measuring distance L _{a k} , L _opt , a correction value K _{opt is} determined thereon. The correction value K _opt results in this case as a function of the two variables L _{a k} , L _opt , wherein the corresponding relationship is stored, for example, in a correction table and from which the associated correction _value K _opt can be respectively taken.

The correction _value K _opt can then be used subsequently for correcting the light wavelength λ _opt and thus for determining the light wavelength λ _{opt, corr} corrected with respect to the environmental influences. From the corrected light wavelength λ _{opt, corr} then again the actually sought measured variable, ie the corrected measured distance L _corr can be determined by multiplying the initially determined optical phase measured value P _opt by the corrected light wavelength λ _{opt, cor} , ie L _corr = P _opt · Λ _{opt, corr} . As an alternative to this procedure it is possible, after determining the correction value K _opt by the simple multiplication of the same with particular optical, uncorrected measurement distance L _opt directly the desired measured quantity L _corr, that is, the corrected measurement distance be determined in accordance L _corr = K _opt · L _opt .

The explained procedure according to the invention can now be described in a second embodiment of the interferometer arrangement according to the invention, which is described in US Pat 2 is shown, still expanding. It is thus possible, within the interferometer arrangement according to the invention, to have one or more further sensors 51 . 52 . 53 along the measuring path, by means of which further environmental parameters such as humidity F, pressure P and gas composition G are determined. In one possible configuration, for example, the environmental parameters humidity and pressure are determined to increase the accuracy. The different sensors 51 . 52 . 53 - In the case of a complex configuration in the form of a gas sensor, a pressure sensor and a humidity sensor - are also the output side with the correction unit 40 connected, ie the thus detected parameters F, P, G can complement ver are used to determine the required correction value K _opt and from this the corrected light wavelength λ _{opt, korr} or the corrected measurement distance L _corr . Otherwise, the interferometer arrangement corresponds to 2 of those 1 ; for the functionally identical components, the identical reference numerals have been used.

In case of using additional sensors 51 . 52 . 53 is advantageous if these are arranged as possible in the range of the measuring axis MA or measuring section. It is sufficient in this case to detect these environmental parameters at one or a few measuring points along the measuring path, since the fluctuations of these parameters along the measuring path are usually very small.

The following are based on the 3a - 3e various variants of the invention interferometer arrangements explained, which differ in particular with respect to the arrangement and specific design of the components of the acoustic function block from the previous examples. Components having the same functionality in these examples as in the above examples are denoted by the same reference numerals as in FIG 1 designated.

3a shows an embodiment of the interferometer according to the invention, in which by the reference numeral 12 the stationary first phase determination unit of the optical interferometer and the reference numeral 11 the associated, schematically indicated radiation reflector on in the measuring direction x movable measuring object 30 is designated. In contrast to the previous examples are on the side of the acoustic interferometer stationary now several sound transmitter 121.1 . 121.2 as well as several with the test object 30 connected sound receivers 122.1 . 122.2 intended. In this way, via the second phase determination unit 26 a determination of the acoustic phase measured value P _{ak can take place} from a plurality of measurements along several lines L1-L4 distributed around the optical measuring axis MA. For this purpose, the determination of a plurality of acoustic phase measured values P _{a k , i} , from these then a mean acoustic phase measured value P _{a k is} formed and of the correction unit 40 is further processed to determine the correction value K _opt and possibly corrected wavelength of light λ _{k orr} and / or from the corrected measurement distance L _corr . It is thus possible to achieve a higher accuracy in the determination of the acoustic phase measured value P _{a k} and thus also the overall measurement.

Preferably, in such an embodiment, the plurality of sound transmitters 121.1 . 121.2 as well as the sound receiver 122.1 . 122.2 each symmetrical - for example, circular - around the stationary interferometer as well as the movable radiation reflector 11 arranged so as to ensure a common resulting measuring axis MA for the determination of the optical and acoustic phase measurements P _opt , P _ak .

alternative for the distribution of several sound transmitters and sound receivers to the respective interferometer components according to the previously explained example it is also possible only the sound transmitter and / or the sound receiver in In terms of its geometry to dimension accordingly to the Requirements for the symmetry of the acoustic components with respect. to meet the optical interferometer. For example, would be about a circular trained sound transmitter and sound receiver can be used at this point, wherein the circle center coincides with the measuring axis MA.

In the 3b illustrated embodiment of the interferometer according to the invention differs from the previously discussed variants on the one hand in the nature of the components that are used in the acoustic function block. It is now provided, instead of the original sound transmitter and sound receiver combined acoustic transmission / reception elements 221.1 - 221.4 use. These elements 221.1 - 221.4 are in turn arranged symmetrically about the stationary as well as about the moving components of the optical interferometer.

On the other hand, by the use of such transmission / reception elements 221.1 - 221.4 determine acoustic phase measurements P _{ak, i} in two different directions of the sound wave, from which in turn a mean acoustic phase measured value P _ak can be determined for further processing. In this way, the possibly existing influence of an air movement along the measuring path on the acoustic phase measurement can be eliminated in an advantageous manner.

The determination of the different acoustic phase measured values P _{ak, i} in two different directions of movement of the sound wave can alternatively also be accomplished by arranging both sound transmitters and sound receivers on both sides of the measurement path. However, this procedure would be more complicated than the proposed use of the combined acoustic transmission / reception elements.

Another variant of the interferometer arrangement according to the invention is shown in FIG 3c shown. On the side of the stationary acoustic components are as in the previous embodiment combined transmit / receive elements 221.1 . 221.22 are provided, which are preferably in turn arranged symmetrically about the stationary optical interferometer components. With the movable measurement object 30 are in this embodiment, in addition to the radiation reflector 11 several sound reflectors 310.1 . 310.2 arranged, which serve for a return reflection of the incident sound waves in the direction of the opposite arranged transmitting / receiving elements. On the side of the measurement object 30 are therefore provided in this embodiment, only passive reflector components for the incident sound wave and the incident beam.

Also in the case of the use of sound reflectors, it would be possible to have only a single component to use that then a corresponding symmetric geometry in relation to the measuring axis. For example, comes about the use a sound reflector with an annular cross-section into consideration, wherein the circle center in turn coincides with the measuring axis MA.

Further can the first time proposed in this example sound reflectors in principle in connection with all previously explained variants and individual measures be used.

At the in 3d illustrated embodiment of an interferometer according to the invention have the acoustic components in the form of the stationary combined transmitting / receiving element 421 as well as the movable sound reflector element 410 a geometry such that it results in a collimating effect on the sound waves. In addition, it can be ensured that the sound waves propagate as far as possible along or at least immediately adjacent to the measuring axis MA.

In the case of the respective acoustic components, it is further provided in this exemplary embodiment that the transmitting / receiving element 421 as well as the sound reflector element each have a central passage opening 422 . 423 for the beam path of the optical interferometer in the region of the optical measuring axis MA have. In this way it can be ensured that the measuring beam path of the optical interferometer runs in the central region of the sound wave.

In the embodiment of 3e Finally, as in the previous example, the acoustic components again have an effective geometry that results in a collimating effect on the sound waves. Here, as acoustic components, a stationary sound transmitter 521 as well as with the measurement object 30 mobile sound receiver 522 trained accordingly. Both components 521 . 522 have a central passage opening as explained above 523 . 524 for the beam path of the optical interferometer in the region of the measuring axis MA.

As already mentioned several times can be based on the 3a - 3e explained individual measures with regard to the acoustic components of the interferometer according to the invention, of course, in any way combine, supplement, etc.

Based on 4a - 4c Finally, a concrete application of the interferometer arrangement or the method according to the invention is explained. All examples in this case relate to the use of the interferometer arrangement in conjunction with a so-called xy table, which is displaceable in a first and second spatial direction x and y and whose position is to be determined. Typical fields of use of such xy tables are found, for example, in lithography systems for semiconductor production, for example in wafer steppers or wafer scanners. Shown are in the schematic representations of 4a - 4c only possibilities for the arrangement of the various components of the acoustic and the optical interferometer on the side of the xy-table, in particular for the case that only passive reflector components are to be provided on this page.

In the embodiment of 4a is an xy table 300 represented, on which a narrow rectangular radiation reflector 611 is arranged, the longitudinal direction in the y-direction - that is perpendicular to the measuring direction x - extends. Further, at the xy table 300 a sound reflector 610 is provided which has a geometric shape such that, as in some of the previous examples, a collimating effect is exerted on the sound waves. When choosing the geometry of the sound reflector 610 It should also be noted that the measured acoustic phase measured value of the reflected sound wave is independent of movement of the xy-table 300 perpendicular to the measuring direction, eg from a movement in the y-direction. Along the y-direction points the sound reflector 610 In this embodiment, therefore, in each case the same parabolic cross-sectional geometry.

In the central area has the sound reflector 610 in this embodiment, a passage opening extending in the y-direction, through which the beam of the optical interferometer to the radiation reflector 611 can get. Alternatively, it may also be provided to integrate the radiation reflector, if necessary, directly into the sound reflector.

In the embodiment of 4b is provided as in the previous example, a radiation reflector 711 at the xy table 300 to arrange, which extends in the y direction. For reflection of the incident sound wave, however, are several discrete sound reflectors 710.1 . 710.2 Distributed in the y-direction distributed along the radiation reflector. The individual sound reflectors 710.1 . 710.2 in turn each have a geometric shape that exerts a collimating effect on the sound waves.

The arrangement of several sound reflectors 710.1 . 710.2 in the y-direction - that is perpendicular to the measuring direction x - has the advantage that in the case of a possible movement in the y-direction more acoustic phase measurements P _{ak, y1} , P _{ak, y2} can be determined and in turn the influence of such a movement the determined phase measured values can be compensated. For example, it would also be possible to determine a phase measured value independent of the movement in the y direction along the measuring direction x.

The embodiment of 4b Finally, in the embodiment of the 4c extended to two measuring axes MA1, MA2 for the xy table 300. The first measuring axis MA1 corresponds to the spatial direction x, the second measuring axis MA2 to the spatial direction y. Along each of the two measuring axes MA1, MA2, an interferometer arrangement according to the invention is provided which, in addition to a first and a second optical interferometer, also provides an acoustic interferometer variant with a first and a second sound transmitter, sound receiver and possibly a first and second sound reflector. In the present example, the version with passive reflector elements was provided on the side of the xy table. That is, each is an optical reflector element extending in the x and y directions 811.1 . 811.2 as well as in the x and y direction each one or more acoustic reflector elements 810.1 - 810.4 arranged.

Alternatively to the examples in the 4a - 4c can of course also be provided on the xy table instead of the sound reflectors as explained in the input example to arrange sound receiver. Likewise, it is possible to use combined transmit / receive elements in such an application as explained above, ie basically all the measures explained above can be used in conjunction with measuring applications for xy tables.

To determine a correct acoustic phase measured value P _{a k} in the measuring direction x, which is corrected with respect to a possible movement of the xy table in the y direction, there are basically two different possibilities in such an application.

For example, as explained in the above examples, it is possible to provide along the y direction for arranging a plurality of sound reflectors or possibly sound receivers and to appropriately calculate the measured values generated in order to obtain a corrected or compensated acoustic phase measured value P _ak .

Alternatively, however, it is also possible to use a second interferometer arrangement according to the invention in the y-direction, as in FIG 4c Suggested - to use measured values with respect to the position in the second spatial direction y for accounting with the acoustic phase measured value in the x-direction, in order to determine such a corrected acoustic phase measured value for the movement in the measuring direction x. In the latter case, the use of only one sound reflector or possibly sound receiver in the x-direction is then required.

The based on the explained Examples of proposed measures with regard to concrete design and / or arrangement of the various Elements of the interferometer arrangement according to the invention of course in any suitable form combine and modify. As part of The present invention therefore exists in addition to those explained Variants of course still further alternative embodiments.

Claims (28)

Interferometeranordnung, consisting of - an optical interferometer for determining the position of a measuring object, which is connected to a radiation reflector and linearly displaceable along a measuring path in a measuring direction, wherein for determining a measurement distance can be determined, - a sound transmitter, a sound receiver and an optional sound reflector, which are likewise arranged along the measuring path or parallel thereto, characterized in that - with the optical interferometer a first phase determination unit ( 12 ) is connected in order to determine an optical phase measured value (P _opt ) along the measuring path, - with the sound transmitter ( 21 ; 121.1 ; 121.2 ; 521 ) and the sound receiver ( 22 ; 122.1 ; 122.2 ; 522 ) a second phase determination unit ( 26 ) to determine an acoustic phase measurement (P _{a k} ), - the first and second phase determination units ( 12 . 26 ) on the output side with a Konektureinheit ( 40 ), which determines from the transferred phase measured values (P _opt , P _{a k} ) a correction value (K _opt ) for compensation of environmental influences in the optical position determination. Interferometer arrangement according to claim 1, characterized in that via the correction unit ( 40 ) by means of the correction value (K _opt ), the determination of a relative to the environmental influences corrected light wavelength (λ _{opt, corr} ) takes place. Interferometer arrangement according to claim 1 or 2, characterized in that via the correction unit ( 40 ) by means of the correction value (K _opt ), the determination of a corrected. With respect to the environmental influences measured distance (L _corr ) takes place. Interferometer arrangement according to claim 1, characterized in that adjacent to the measuring path one or more sensors ( 51 . 52 . 53 ) are arranged to generate sensor output signals with respect to different environmental parameters, wherein the sensors ( 51 . 52 . 53 ) on the output side with the correction unit ( 40 ) and the transmitted sensor output signals are also used to determine the correction value (K _opt ) in the correction unit ( 40 ) serve. Interferometer arrangement according to claim 4, characterized in that as a sensor ( 51 . 52 . 53 ) are arranged in each case at least one pressure sensor and a humidity sensor adjacent to the measuring section. Interferometer arrangement according to claim 1, characterized in that a plurality of sound transmitters ( 121.1 . 121.2 ), several sound receivers ( 122.1 . 122.2 ) and several optional sound reflectors ( 310.1 . 310.2 ) are arranged along the measuring section. Interferometer arrangement according to claim 1, characterized in that at least one sound transmitter ( 121.1 . 121.2 ; 521 ) is stationary and at least one sound receiver ( 122.1 . 122.2 ; 522 ) on the displaceable measurement object ( 30 ) are arranged. Interferometeranordnung according to claim 1, characterized in that at least one sound transmitter and at least one sound receiver are arranged stationary and at least one sound reflector ( 310.1 . 310.2 ) on the displaceable measurement object ( 30 ) is arranged. Interferometer arrangement according to at least one of the preceding claims, characterized in that the sound transmitter ( 21 ; 121.1 ; 121.2 ; 521 ), Sound receiver ( 22 ; 122.1 . 122.2 ; 522 ) and possibly sound reflectors ( 310.1 . 310.2 ) symmetrically about the stationary interferometer components and the movable radiation reflector ( 11 ), so that in this way a common measuring axis (MA) for the determination of the optical and the acoustic phase measured value (P _opt , P _ak ) results. Interferometer arrangement according to at least one of the preceding claims, characterized in that the sound transmitter ( 521 ) and / or the sound receiver ( 522 ) and / or the optional sound reflector have a geometry such that a collimating effect on the sound waves results. Interferometer arrangement according to at least one of the preceding claims, characterized in that the sound transmitter and the sound receiver as a combined transmitting / receiving element ( 221.1 . 221.2 ; 221.3 . 221.4 ; 221.1 . 221.2 ; 421 . 410 ) are formed. Interferometer arrangement according to claim 10 or 11, characterized in that the sound transmitter ( 521 ) and / or the sound receiver ( 522 ) and / or the sound reflector and / or the transmitting / receiving element (421, 410) has a central passage opening ( 422 . 423 ; 523 . 524 ) for the beam path of the optical interferometer. Interferometer arrangement according to at least one of the preceding claims, characterized in that the measuring object ( 300 ) is formed as an xy-table, which is displaceable in a first and a second spatial direction (x, y) and at the at least one radiation reflector ( 611 ; 711 ; 811.1 . 811.2 ) as well as at least one sound reflector ( 610 ; 710.1 . 710.2 ; 810.1 . 810.2 . 810.3 . 810.4 ) or at least one sound receiver are arranged, wherein the first spatial direction of the measuring direction (x) corresponds and the second spatial direction (y) is oriented perpendicular thereto. Interferometer arrangement according to claim 13, characterized in that the at least one sound reflector ( 610 ) or the at least one sound receiver is designed such that the acoustic phase measurement value (P _ak ) to be measured of the sound wave reflected therefrom is independent of a movement of the xy table ( 300 ) in the second spatial direction (y). Interferometer arrangement according to claim 14, characterized in that along the second spatial direction (y) a plurality of sound reflectors ( 710.1 . 7190.2 ; 810.1 . 810.2 ) or sound receiver on the xy table ( 300 ) are arranged. Interferometer arrangement according to claim 15, characterized in that - also along the first spatial direction (x) a plurality of sound reflectors ( 810.3 . 810.4 ) or sound receiver are arranged on the xy table and along the first spatial direction (x) further at least one further radiation reflector ( 811.2 ) is arranged and - A second optical interferometer and a second sound transmitter, a second sound receiver and an optional second sound reflector are arranged along the second spatial direction (y). A method for operating an interferometer arrangement, having - an optical interferometer for determining the position of a measurement object which is connected to a radiation reflector and linearly displaceable along a measurement path in a measurement direction, wherein a measurement distance is determined for determining the position, - a sound transmitter, a sound receiver and a optional sound reflector, which are also arranged along the measuring path or parallel thereto, characterized in that - with a first phase determination unit ( 12 ), which is connected to the optical interferometer, with which an optical phase measured value (P _{o pt} ) along the measuring path is determined, - with the sound transmitter ( 21 ) and the sound receiver ( 22 ) a second phase determination unit ( 26 ), with which an acoustic phase measured value (P _{a k} ) is determined, - the first and second phase determination unit ( 12 . 26 ) on the output side with a correction unit ( 40 ) are connected with the from the transferred phase measured values (P _ak , P _opt ) a correction value (K _opt ) for compensating environmental influences in the optical position determination is determined. A method according to claim 17, characterized in that by means of the correction value (K _opt ) with respect to the environmental influences corrected light wavelength (λ _{opt, korr} ) is determined. A method according to claim 17 or 18, characterized in that by means of the correction value (K _opt ) with respect to the environmental influences corrected measuring distance (L _corr ) is determined. A method according to claim 17, characterized in that for determining the correction value (K _opt ) further environmental _parameters (F, P, G) by means of one or more sensors ( 51 . 52 . 53 ) and taken into account. A method according to claim 17, characterized in that - an uncorrected optical measuring distance (L _{op t} ) is determined from the optical phase measured value (P _opt ) and the uncorrected light wavelength (λ _opt ), - from the acoustic phase measured value (P _ak ) and the uncorrected one Sound wavelength (λ _ak ) an uncorrected acoustic measuring distance (L _{a k} ) is determined, - from the optical measuring distance (L _opt ) and the acoustic measuring distance (L _ak ) a Korrkturwert (K _opt ) for the correction of the optical radiation wavelength (λ _opt ) determined is - from the multiplication of the correction value (K _opt ) with the optical radiation wavelength (λ _opt ) the corrected optical radiation wavelength (λ _{opt, korr} ) is formed. A method according to claim 21, characterized in that from the multiplication of the optical phase measured value (P _opt ) with the corrected optical radiation wavelength (λ _{opt, korr} ) with respect to the environmental influences corrected measuring distance (L _{k orr} ) is formed. A method according to claim 21, characterized in that the correction value (K _opt ) as a function of the uncorrected acoustic measuring distance (L _ak ) and the uncorrected optical measuring distance (L _{o pt} ) is stored in a correction table and from the correction table the respectively associated correction value (K _opt ) is removed. A method according to claim 17, characterized in that the determination of the optical and acoustic phase measured value (P _opt , P _{a k} ) takes place simultaneously. Method according to at least one of the preceding claims, characterized in that - a plurality of acoustic phase measured values (P _{ak, i} ) are determined, - a mean acoustic phase measured value (P _{a k} ) is formed from the plurality of acoustic phase measured values (P _{ak, i} ), from the correction unit ( 40 ) the mean acoustic phase measured value (P _ak ) is used to determine the corrected measuring distance (L _{k orr} ). A method according to claim 25, characterized in that a plurality of acoustic phase measured values (P _{ak, i} ) are determined in different directions of the sound wave, from which then the mean acoustic phase measured value (P _ak ) is formed. A method according to claim 25, characterized in that in the case of a movement of the measurement object ( 300 ) in a second spatial direction (y) perpendicular to the measuring direction (x) a plurality of acoustic phase _{measured values} (P _{ak, y1} , P _{ak, y2} ) are determined and from this an independent of the movement in the second spatial direction (y) acoustic phase _{measured value} along the measuring direction ( x) is determined. A method according to claim 17, characterized in that in the case of a movement of the measurement object ( 300 ) in a second spatial direction (y) perpendicular to the measuring direction (x) the measured values generated via a second interferometer arrangement with regard to the position of the test object ( 300 ) in the second spatial direction (y) for determining a corrected acoustic phase measured value (P _ak ) for the movement in the measuring direction (x).