DE102008033548A1 - Optimizing division of crystalline starting body in defect-poor region, comprises determining position of crystal axes and three-dimensional shape of the body, and fixing useful volume by determining location of crystal defects in the body - Google Patents

Abstract

The method comprises determining a position of the crystal axes, determining a three-dimensional shape of the crystalline starting body, fixing an useful volume by determining the location of crystal defects in the crystalline starting body with electromagnetic waves as detecting radiation, and adapting a predetermined shape of monocrystalline blanks to be produced in the usable volume using a computer-controlled iteration process under the usage of maximum usable volume. The position of the crystal axes is determined by fixing [111]-surfaces of the crystalline body. The method comprises determining a position of the crystal axes, determining a three-dimensional shape of the crystalline starting body, fixing an useful volume by determining the location of crystal defects in the crystalline starting body with electromagnetic waves as detecting radiation, and adapting a predetermined shape of monocrystalline blanks to be produced in the usable volume using a computer-controlled iteration process under the usage of maximum usable volume. The position of the crystal axes is determined by fixing [111]-surfaces of the crystalline body in relation to the position of the crystalline body. For determining the location of the crystal defects, the crystalline body is illuminated from different spatial directions and is arranged between polarizers, the recording of an image takes place with an image recording device and the change of the light intensity is calculated in an analysis device. The crystal and/or a light source rotate and a signal transmitter transmits the rotation angle of a data processing system with a memory for determining the location of the crystal defects. The position of monocrystalline areas is displayed in an image processing device.

Description

The The invention relates to a method for optimizing a fragmentation a crystalline starting body in defect-free or Crystal clear or low volume ranges.

For The application in optical components are increasingly becoming crystals used, especially for wavelengths, which are outside the visible range. That is how it is z. B. an increasing demand for monocrystalline material Alkali and alkaline earth fluorides (calcium (II) fluoride, barium (II) fluoride, Strontium (II) fluoride, sodium fluoride, potassium fluoride, cesium fluoride etc.) for use such as UV lithography or microlithography and for lenses and parts, windows and prisms for Irradiation and imaging devices or z. B. telescopes for astronomy. Similarly, put crystals in the infrared spectral range the basis for many optical Elements.

In particular, calcium fluoride single crystals (CaF ₂ ) are used as starting materials for optical components in DV photolithography (DUV = deep UV) at wavelengths below 250 nm, in particular for the wavelengths 248 nm, and below 200 nm, in particular for 193 nm and 157 nm needed.

Calcium fluoride crystals for use in projection optics for the UV and DUV areas must be free from crystal defects be about block boundaries, d. H. the material must be a monocrystalline Being a body whose crystal structure is as free as possible of disturbances.

The Quality of a crystal is not in practice only by such block boundaries, but also by a variety often limited to small crystal defects, despite their low spatial Extension strong local variations of optical properties in the volume of the starting material.

The occurring in said single crystals local crystal defects include inclusions, bubbles, veils, crystallographic Injuries, sliding bands (area defects), scattering particles and small angle grain boundaries. At small angle grain boundaries store often impurities, in the case of calcium fluoride z. As calcium oxide precipitates leading to local inhomogeneities the refractive index can lead, but if necessary also generated around voltages around the small angle grain boundaries become.

Currently the evaluation of the optical quality characteristics takes place Crystals usually z. T. visually by a specialist. The Classification of the raw material thus depends on the experience and the abilities of the respective expert from and subject therefore subjective assessments. It is not because of that uniformly.

Single crystals are produced in crystal growing plants. The geometric shape and size of the crystal becomes large determined by the breeding arrangement. The crystals must therefore subsequently by sawing and the like be brought into the desired starting form. The production Such larger volume (ie with a diameter> 25 cm, in particular ≥ 30 cm) of highly homogeneous bodies (crude crystals, etc.) as starting material for optical elements that are as free of crystal defects as possible but it is very expensive.

at However, the production of an optical element is regular aspired to make a blank of the element so from the large volume To cut out the initial crystal, that he has only a single crystallographic Having orientation and optionally present in the starting crystal Crystal defects outside the cutting lines and thus outside of the blank volume to come to rest. So far, to ensure this, more or less generous of such crystal defects cut around and tried out the remaining crystal material optical elements of the desired size manufacture. It was therefore not possible until now, the volume of the crystalline body in a targeted manner.

task The invention therefore provides a method for optimized Fragmentation of crystalline bodies, with which the volume a crystalline body with maximum volume yield can be used, whereby the crystalline body so divided will ensure that the individual partitioned areas are trouble-free are, d. H. they have no crystal defects.

These Object is according to the invention with a method to optimize the fragmentation of a crystalline, in particular dissolved monocrystalline starting body, wherein in a step (a) the determination of the position of the crystal axes (b) the three-dimensional spatial form of the crystalline starting body is determined (location and size of the outer surfaces or contours), (c) the usable volume by determining the Position of the crystal defects in the crystalline starting body takes place and in a step (d) a predetermined spatial form of a or more monocrystal blanks to be produced in the three-dimensional Spatial form of the parent body controlled by a computer Iteration method is fitted so that it is the volume of the defect-free Range optimally or maximally exploited.

The Monocrystalline blanks are preferably so from the crystalline Starting body sawed or cut that they have the same crystallographic orientation. Accordingly the crystal blanks have no specific relation to the spatial form of the initial crystalline body. The usable volume of the crystalline body is additionally through other crystal defects such as inclusions, Blisters, veils, crystallographic injuries, sliding bands (Area defects), scattering particles and small-angle grain boundaries limited. The division of the crystalline body takes place Therefore, so that these other crystal defects outside the specified usable monocrystalline areas or volume lie or that these defects are the edges of the usable Represent volume.

With The method according to the invention makes it possible to in the three-dimensional spatial form of the crystalline initial or Base body a three-dimensional image of the examined in the To create bodies found monocrystalline areas, whose volume is limited by crystal defects. In this three-dimensional overall picture of the crystalline body can then be the monocrystalline regions with the same crystallographic Orientation with the best possible use of the remaining Space in the body by means of a known computer order controlled iteration process. This is special with expensive raw materials, such as large-volume single crystals, of particular advantage because this is a crystal orientation-dependent Allocation allows.

One crystalline body in the context of the present invention For example, a crystal block or ingot, i. H. an oriented, crystalline, large-volume starting or base body. Preferably, it is an oriented, monocrystalline body, especially a cultivated crystal.

One monocrystalline region in the sense of the present invention a volume or space in the starting material or starting body, which has only one crystallographic orientation.

crystal defects For the purposes of the present invention, for example, block boundaries, Inclusions, blisters, veils, crystallographic injuries, Slip belts (surface defects), scattering particles and Small-angle grain boundaries.

One Iteration method in the context of the present invention is a Procedure in which access to a database or data structure iteratively (stepwise) or repeated.

Prefers the crystalline body is a crystalline body selected from the group consisting of calcium (II) fluoride, Barium (II) fluoride, strontium (II) fluoride, magnesium (II) fluoride, sodium fluoride, potassium fluoride and cesium fluoride. Particularly preferred is the crystalline Body calcium fluoride.

The Production of single crystals is known per se and can according to the obtained from the prior art methods.

Crystalline bodies can be prepared, for example, by the Bridgeman method or the VGF method, as described, for. B. in the DE 100 10 484 A1 is described. Other methods are, for example, the Czochralski method, the TSSG (Top seeded solution growth), etc.

to Determination of crystal defects or defects is the crystalline bodies to be examined for example in one Dark space determined by means of illumination diffuse scattering and then stress birefringence and slip ribbons analyzed.

The Lighting is preferably done under white light to the to determine diffuse scattering. It becomes the crystalline body in its volume radiated by the light and the scattering also after Adaptation of the eye to the dark space determined visually. It will a scattering called diffuse when the eye of the beholder no single scattering centers can dissolve and that diffuse Crystal volume evenly illuminated (foggy) or cloud-like) enlightened appears. A weak diffuse Scattering means that they are only for a trained eye a professional in the dark room is perceptible, whereas one is no longer permissible, medium dispersion even for a layman is recognizable. For the inventive Processes are only crystalline solids on to use if these have no or only weak diffuse scattering demonstrate.

When Any white light can be used Any lamp can be used. Preferably, the beam is set slightly divergent by a reflector and capacitor. A Lamp usable in the method according to the invention is, for example, a halogen lamp Osram with the trade name Xenophot HLX 54510 (12V, 50W).

Sliding bands are indicated by stripes between crossed polarizing filters. However, they can be eliminated in the annealing process and then do not further negatively affect the quality of the crystalline bodies. In a particular embodiment, the position of these and other defects can be recorded by means of a CCD camera from at least three spatial directions and stored electronically, in particular in a computing unit who the. The three-dimensional position and the course of the crystal defects can then be determined from the values determined by means of images from three spatial directions. Preferably reference lines are attached to the crystal, which facilitate a later assignment of the position of the detected defects.

In an expedient embodiment the position of the crystal axes in relation to the position or spatial form of the crystalline body by defining a reference plane, preferably the [111] plane of the starting crystalline body or crystal ingots.

The determination of the [111] plane of the crystalline starting body can be carried out, for example, by knocking off an edge at two points of the crystalline body. In this way, the [111] plane is preserved or exposed as a fracture surface. This is particularly preferred for CaF ₂ , since these crystals are very easy to split along [111].

By the determination of the [111] plane (cleavage plane) with the growth surface (cut surface of the crystalline Body) formed angle, the location can be the other crystal plane also indicated by an angle. Then a reference line is set, for example by using a pin on the growth surface one radial line is drawn and the angles of the exposed [111] plane with respect to this line (azimuth angle). In this way it is possible, the location of single monocrystalline, d. H. defect-free areas in the room and in relation to the crystalline Specify output body exactly. This data will be in the data processing system with memory stored.

alternative can the position of the crystal axes by means of X-rays, preferably on a growth surface.

at the measurement of the orientation of the crystal axes becomes, for example the Laue method used in which the orientation of the crystal axes through Irradiation of a sample with X-rays is measured.

The Laue method has the advantage that different orientations the crystal axes due to detection of various reflexes, such as about [111], [110] and the like, simply measured and controlled can be.

There the Laue method is based on a lateral reflection method, The Laue method has the advantage that even measuring a Large diameter sample is possible without that the sample is damaged.

method for evaluating the orientation of the crystal axes include, for example Method based on X-rays.

Provided An X-ray diffractometer is used on a Side of an x-ray tube opposite to a diffractometer a Laue camera for back reflection Installed. The distance between the sample surface and the movie is set to a few tens of millimeters. The X-ray tube uses a Mo-target and the Film recording takes place with a tube voltage of 40 kV, one Tube current of 50 mA for one exposure time of 60 sec. The analysis of the orientation is done by manual Calculation based on a Polaroid photograph of the obtained Laue pattern or is calculated by taking the photograph with the help of a scanner is loaded into a computer.

The Laue method is an X-ray diffraction method and is arranged so that white X-rays one solid single crystal strip. Since the Bragg angle θ with respect is set to all levels of the crystal, each learns Level a diffraction by selecting X-rays with a wavelength λ, the Bragg condition λ = 2D sin θ with respect to the Bragg angle Θ satisfied. The Laue method has three methods, including the Transmission method, the back reflection method and the Page reflection method, by varying the relative positional relationship between the x-ray source, the crystal, the film or the CCD camera.

at the transmission method is the film or the CCD camera behind arranged the beam, so that rays are recorded, the were bent in the forward direction.

at The reverse reflection method is the movie in between arranged the crystal and the X-ray source, and the Rays go through an opening formed in the film through and rays in the reverse direction be bent are recorded.

at the side reflection method, the X-ray source is arranged that the rays at a certain angle of incidence ω on hit the crystal, and the film or CCD camera is in a position arranged in relation to the incident beam is rotated by φ to bend in any lateral direction Record rays.

In each of these methods, the diffracted rays form Laue spots on the screen or a fluorescent screen. Since the position of the Laue stain in each method is determined by the relative loading With reference to the crystal orientation with respect to the incident beam, the position of the Laue patches is used to determine the crystal orientation by utilizing this fact.

The Laue method makes it possible to different orientations the crystal axes, as in [111] and [110], are easy to measure, and it's both in terms of measurement accuracy and in terms of Speed suitable for the present invention.

to Indication of the orientation of the crystal axes are Miller indices used. The Miller index is the reciprocal of a ratio between the distance from the origin of a unit lattice of a crystal to the intersection of the plane with the crystal axis and the unit length the axis. In the case of a cubic system, such as calcium fluoride, when one assumes that the unit length of each crystal axis A is, the Miller index is {hkl} if a certain level is the Axes at points a / h, a / k and a / l intersects. In the cubic system is the orientation [hkl] always perpendicular to the plane {hkl} with the same index, and direction, in a symmetrical relationship are represented by an index and indicated by <>.

For example There is a device for measuring the orientation of the crystal axes according to the Laue method from an X-ray source, a Rehearsal stage and a CCD camera. X-rays meet to the sample, and thereby obtained diffracted rays analyzed as a Laue pattern.

In Another step is the optical properties of the crystalline Solid state, in particular the spatial location of respective crystal defects determined.

Prefers the determination of the position of the crystal defects with electromagnetic Waves as detection radiation.

preferred Detection radiation is visible light, in particular coherent Light such as As laser light and / or mono- or polychromatic white light, x-rays or gamma rays.

Preferably the crystal is irradiated with polarized light, which by means of a polarizer film and polarized through an analyzer film whose polarization is 90 ° to the polarizer is turned. In this way, in the polariscope the voltage-induced Birefringence visualized.

The Detection radiation is radiated from the outside, inside of the examined crystalline body changed (bent, weakened, scattered, etc.) and after the escape captured from the body by detectors. The detection radiation can also be generated in the body itself, for example by Fluorescence or by resonance effects as in ESR and NMR, where then type and scope of the origin statements about allow the body inside. The selection of detection radiation takes place on the basis of the properties of the body to be examined, d. H. taking into account the interaction of the detection radiation with the body or crystal defects that are detected should. The prerequisite for this, of course, is in the Rule that the detection radiation is the crystalline body not changed. For translucent crystals as calcium fluoride is z. B. to note that radiation of high intensity or high quantum energy, the transmission properties permanently can change. Also should the detection radiation with relatively little effort into the body to be tested can be coupled. So it is with these bodies Before measuring a polish usual, the effort but should not exceed the usual level.

Prefers Be light boxes, as they are for viewing be used by X-ray films. Especially preferred become industrial light boxes type UNI of the company WRG.

In a preferred embodiment of the crystalline Body for determining the location of the crystal defects irradiated in different spatial directions.

advantageously, The crystalline body is in a measuring arrangement placed, which allows the crystal of different, preferred from all, spatial directions or irradiate.

In a preferred embodiment of the crystalline Body for determining the location of crystal defects between Polarizers arranged.

Prefers becomes the crystalline body between two polarizers arranged. Two crossed polarizers produce a polariscope.

to Determination of the position of the crystal defects in the crystalline body this is arranged between polarizers and the polarization change determined in a known manner. This process will follow from several sides or with different entry directions the electromagnetic waves repeated. This way will a spatial representation of the total occurring in the crystal Block interfaces and other crystal defects detected.

in principle It is possible to have crystal defects both on the back the radiation source, d. H. with the passing beam, as well on the irradiated side, d. H. with the reflected beam, too determine. In addition, it is possible the Ray scattered laterally on crystal defects in the body capture.

Preferably the body is irradiated from at least three spatial directions and thereby the passing beam, reflected beam or laterally scattered Beam detected.

Conveniently, is the crystalline body for measurement on a holder placed in the polariscope by complete rotation of two axes allows the crystalline body in any To bring angular position. Two rotary encoders on the axles of the bracket of the crystalline starting body or ingot to be determined in the polariscope transmit the position of the crystal, d. H. the angle of rotation, to a data processing system with memory.

In another preferred embodiment of the invention becomes the surface of the crystalline to be examined Body to increase the coupling and decoupling the detection radiation, d. H. to reduce the reflection the surface when entering and / or leaving, with a coupling aid Mistake. A preferred coupling aid is, for example an immersion oil, as is known from microscopy is. The aids preferably have a similar Refraction on like the crystalline body to be examined.

In Another preferred embodiment is attached to the to be examined object a fitting piece attached, which Form-fitting to the surface of the crystalline body is adjusted. On the side facing the detection radiation this fitting is even, so the electromagnetic wave can occur as vertically as possible. That way Artifacts avoided, as they arise, for example, when the Radiation at different angles in the body surface occurs and diffracted differently, since here the wave in general perpendicular to the surface in the fitting piece and from there enters the crystalline body to be examined. Again, it is preferable between fitting piece and the Object a coupling aid such as immersion oil to arrange.

In Another preferred embodiment is for the determination the location of the crystal defects recording at least one image made with an image pickup device.

The Recording takes place by means of a punctiform, linear and sheet-like electronic detector (image pickup device). A preferred image pickup device is a CCD camera, infrared camera or another imaging device. Especially preferred is a CCD camera or a CMOS camera as a recording device used.

In Another preferred embodiment is the Determination of the position of the crystal defects by means of a signal generator, which transmits the rotation angle to a data processing system with memory.

The Rotation angles give the position of the crystalline body between the polarizers.

In Another preferred embodiment is for the determination the location of the crystal defects the change in light intensity calculated in an analyzer.

The crystal defects thus found are then compared with respect to their spatial location, its extent and intensity captured and in the coordinate system of the crystalline solid embedded. In this way, crystal defects such as Grain boundaries, slip bands, bubbles and inclusions determine the exact spatial position of individual monocrystalline areas.

The Location of the crystal defects and monocrystalline areas is in one Data processing system with memory entered.

In Another preferred embodiment is the layer of monocrystalline regions in an image processing device displayed.

there becomes the quality of the respective monocrystalline regions on the screen preferably represented by a color. To this Way may be in the search for specific qualities due to the Color easily the quality you are looking for readily found in the crystalline body and quickly be cut out accordingly.

In Another step is the raw crystal quality of the crystalline body. These are the Kleinwinkelkorngrenzen certainly.

Within small-angle grain boundaries, tilting of the crystal axis of subgrains with respect to one another is understood within a single crystal, which forms an angle of a maximum of approximately 5 ° relative to one another. The determination of the small-angle grain boundaries is known per se and is usually carried out in the polariscope. In this case, the crystalline body to be examined is also wetted by means of an immersion liquid and between two crossed polari provided. According to the invention, the raw crystal between the polarizers is preferably arranged with ground surfaces, in particular ground on all sides. The determination of the tilt then takes place on the basis of comparison bodies whose tilt angle by means of X-ray diffractometry, z. B. by means of a device called Crysotax probe Röntec, previously determined.

The Raw crystal quality RKQ 0 is a crystal that is not noticeable Small angle grain boundaries and no noticeable diffuse scattering. RKQ 1 does not mean small angle grain boundaries but a low perceptible diffuse scattering and possibly low fluorescence. RKQ 2 means weak to medium small angle grain boundaries, where weak small-angle grain boundaries flat and mean small-angle grain boundaries star-shaped or modified run. RKQ 3 means that the small angle grain boundaries cross and across a certain area, without a significant preferential direction run. RKQ 4 with small angle grain boundaries extending over the entire area is discarded.

According to the inventive method is in one step (c) determining the location of a monocrystalline body.

there the position of the monocrystalline body is determined that the body preferably only from a crystalline orientation and preferably does not contain any defective areas such as small angle grain boundaries and scattering particles.

On This way monocrystalline bodies can take shape a flat cylinder are generated, the cylinder axes in a of the four symmetry-equivalent [111] directions. Alternatively, the other symmetry equivalents can also be used Directions are selected. This cylinder comes with the Image editing device displayed and can be displayed within the Form of the crystalline body using the mouse or keyboard be moved. Only one parallel shift is permitted in each case, otherwise the crystallographic orientation changes would.

Provided an optimal shape of the cylinder with the best quality for example, with respect to the [111] orientation or the [110] orientation or for the maximum diameter is found the location of this form stored in the data processing system.

According to the inventive method is in one step (d) the position of further monocrystalline bodies by means of a Computer controlled iteration process for optimal utilization of the volume of the crystalline body.

to optimal utilization of the volume takes place on the basis of the specified Form of a first cylinder a computer controlled division of the raw material of the crystalline body in monocrystalline bodies with a crystallographic orientation that does not have crystal defects have, taking into account parameters such as required Cutting allowances and optimization of the cutting guide with minimal cutting losses. Such a division is by means of per se known iteration method possible. It goes the iteration method so that overlap of inlaid cylinders are avoided and also no Regions of the cylinder outside the volume of the crystalline body are located.

The Invention thus enables a complete determination of crystal defects in a crystalline body with the The goal of optimized material utilization for different Delivery products. The invention is particularly advantageous to apply in the case of holistic and automatic fragmentation and allocation of crystalline bodies covering a variety of area boundaries in the crystalline body.

One particular advantage of the invention is that limited and expensive Materials, such as calcium fluoride, by minimized Cut losses and increase the yield considerably better can be exploited. If desired, can The procedure will be interactively designed to help employees in the process to support optimized allocation.

The Location of the monocrystalline areas is in the data processing system saved and as a specification of the cut for the separation technique (eg sawing, splitting, breaking) used.

The Invention also relates to the implementation of the invention Process for the production of lenses, prisms, optical windows and optical components for DUV lithography, steppers, Excimer lasers, wafers, computer chips and integrated circuits and electronic devices containing such chips.

With in particular, it is the process of the invention also possible, lenses, prisms, light-conducting rods, optical windows and optical devices for the DUV lithography produce. The method therefore also finds particular Application for the production of steppers and excimer lasers and thus also for the production of integrated circuits as well as electronic Devices such as computers containing computer chips and others electronic devices, which are chip-type integrated circuits contain.

The Invention will be explained in more detail in the following examples become. Show here

1 a schematic device for carrying out the method according to the invention,

2 a crystal ingot with the course of its crystal planes and axes and

3 an inventively adapted position of a given herauszusägenden crystal blank with the respective saw axes.

1 shows one on a rotatable bearing ( 4 ) arranged crystalline Ausgangsingot ( 9 ). The rotatable ingot carrier ( 4 ) has roller bearings ( 10 ), so that the crystalline initial ingot not only along the vertical axis of the crystal carrier (red 1 ) is rotatable but also about its longitudinal axis (red 2 ). The crystalline ingot lies between crossed polarizing filters ( 3 ) and ( 6 ) and by means of a lighting system ( 2 ) backlit. The transmitted light is detected by means of a CCD camera ( 7 ) and the data is sent to a computing unit ( 8th ) forwarded. The arithmetic unit ( 8th ) is connected to the rotary and pulse encoders of the ingot carrier ( 4 ) connected. In this way, each movement or rotation of the crystalline ingot and thus also its position is stored by the computer and can thus be assigned to the corresponding pattern recorded with the CCD camera. Computer ( 8th ) shows a finished image in which crystalline blanks, such as lens blanks, are arranged by means of an iterative process, making optimum use of the defect-free volume. In this way, then cut or saw patterns are made, as in 3 is shown.

2 shows a crystalline ingot grown along the <111> axis ( 9 ) with its typical crystal planes. By knocking off a small edge, these levels can be set immediately without further ado.

A sawing pattern determined by means of the method according to the invention is described in 3 shown. The upper part of 3 a plan view of the round crystalline ingot, from which a pie-like piece is cut out. As shown in the side view, a blank is then separated from this cake-like piece according to the lower sectioning instructions with the specified angles and sawing planes. In this way, a defect-free monocrystalline blank for further processing, especially for optical purposes, is obtained.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• DE 10010484 A1 [0020]

Claims (11)

Method for optimizing a division of a crystalline starting body comprising the steps (A) Determining the position of the crystal axes, (b) determining the three-dimensional Spatial form of the crystalline initial body, (c) Determine the usable volume by determining the location of crystal defects in the crystalline source and (d) fitting one predetermined spatial form of one or more monocrystal blanks to be produced in the usable volume by means of a computer-controlled iteration method taking advantage of the maximum usable volume. Method according to claim 1, characterized in that that the crystalline body is a crystalline body selected from the group consisting of calcium (II) fluoride, Barium (II) fluoride, strontium (II) fluoride, magnesium (II) fluoride, sodium fluoride, Potassium fluoride and cesium fluoride. Method according to claim 1 or 2, characterized that the position of the crystal axes in relation to the position of the crystalline Body by setting the [111] surfaces of the crystalline body is determined. Method according to one of the preceding claims 1-3, characterized in that the determination of the location the crystal defects with electromagnetic waves as detection radiation is determined. Method according to one of the preceding claims 1-4, characterized in that for determining the position the crystal defects of the crystalline bodies from different Spatial directions is illuminated. Method according to one of the preceding claims 1-5, characterized in that the crystalline body for determining the position of the crystal defects between polarizers is arranged. Method according to one of the preceding claims 1-6, characterized in that for determining the position the crystal defects the inclusion of at least one image with a Image recording device takes place. Method according to one of the preceding claims 1-7, characterized in that for determining the position the crystal defects the crystal and / or a luminous source turned and a signal generator, the rotation angle to a data processing system transmitted with memory. Method according to one of the preceding claims 1-8, characterized in that for determining the position the crystal defects the change in light intensity is calculated in an analyzer. Method according to one of the preceding claims 1-9, characterized in that the location of monocrystalline Areas is displayed in an image processing device. Method according to one of the preceding claims 1-10, characterized in that it is for the production of Lenses, prisms, optical windows and optical components for DUV lithography, steppers, excimer lasers, wafers, Computer chips, and integrated circuits and electronic Equipment containing such chips is used.