TOPOGRAPHIC MEASUREMENT DEVICE AND TOPOGRAPHIC MEASUREMENT METHOD

Abstract

TOPOGRAPHIC SURVEYING DEVICE AND TOPOGRAPHIC SURVEYING METHOD A topographic surveying device comprises a sample holder (1) that receives a sample (2). A first projector (3) applies a first textured light (4) to a first part (2a) of the sample (2). A second projector (5) applies a second textured light (6) to a second part (2b) of the sample (2) that differs from the first part (2a). A first camera (7) observes the first textured light applied to the first part (2a) to acquire first images (8). A second camera (9) observes the second textured light (6) applied to the second part (2b) to acquire second images (10). The second textured light (6) has patterns with a second repetition interval that is lower than the first repetition interval of the patterns of the first textured light (4).

Description

Title of the invention: TOPOGRAPHIC MEASUREMENT DEVICE AND TOPOGRAPHIC MEASUREMENT METHOD technical field

[0001] The invention relates to a topographic measurement device and a topographic measurement method. Previous technique

[0002] In many technical fields related to printed circuit boards, different materials are combined with specific patterns to form electrical or electronic functions. These patterns mean that the volume of a printed circuit board is not homogeneous, causing it to deform anisotropically depending on temperature and over time. Printed circuit boards also generally have elements that protrude from a main surface. These protruding elements must have the most precisely controlled shape and dimensions possible. For example, protruding elements are electrically conductive pads that serve as electrical contacts for an electronic chip or other electronic device. Proper dimensional control of the protruding elements ensures efficient electrical contact.

[0003] It is important to be able to measure the shape and dimensions of the multiple protruding elements as precisely and quickly as possible. It is also important to know the general or specific deformation of a chip or printed circuit board in order to anticipate the causes of failure.

[0004] It is known to measure the dimensions of protruding and deformed features of a chip using an optical method. Textured light is applied to the surface of a sample. The textured light defines a plurality of repeating patterns that are applied to the surface of the sample.

[0005] Several images are acquired of the sample surface illuminated by textured light. By analyzing the different images, it is possible to calculate the dimensions and shape of the protruding elements and / or to calculate the three-dimensional deformation of the chip.

[0006] The quality of the measurement is highly dependent on the quality of the images acquired and the characteristics of the textured light. Textured light defines several areas with color differences, typically black and white areas, preferably with a transition through shades of gray. The distance between two black areas or two white areas determines the resolution of the Deformation measurement. The quality of the measurement also depends on the resolution of the textured light, that is, the distance between two white areas or two black areas. The resolution is limited by the textured light formation technique as well as by physical limitations. Since the study area is small, it is not possible to have an infinite fringe density.

[0007] Logically, the quality of the measurement depends on the optical performance of the camera, that is, the resolution of the image acquired by the camera, which corresponds to the number of pixels per unit length. For a given sample and a given camera, a compromise must be found between the measurement definition achievable by the textured light and the camera's measurement resolution. It is pointless to provide textured light with a very small repetition rate if this rate is significantly lower than the camera's resolution. Conversely, a camera with a high resolution will be limited by the resolution of textured light with a coarse repetition rate.

[0008] In order to maintain a reasonable size and cost, it is not advantageous to have a camera with a large collection area and a low resolution step. It is also counterproductive to seek the finest possible textured light for measuring coarse sample deformations. Depending on the type of deformation to be measured, the characteristics of the textured light and the camera resolution must be adapted. Object of the invention

[0009] An object of the invention consists of providing a topographic measurement device which presents a better compromise between its ability to measure a coarse deformation and its ability to measure a fine deformation.

[0010] This result is to be achieved by means of a topographic measurement device comprising: - a sample holder intended to receive a sample; - a first projector intended to apply a first textured light to at least a first part of the sample; - a second projector intended to apply a second textured light to at least a second part of the sample, the second part being different from the first part; - a first camera designed to observe the first textured light applied to the first part of the sample to acquire a first series of images; - a second camera designed to observe the second textured light applied to the second part of the sample to acquire a second series of images; - a control circuit connected to the first projector, the second projector, the first camera, and the second camera, the control circuit being configured so that the second textured light has patterns with a second pitch of repetition weaker than a first step of repetition of the patterns of the first textured light.

[0011] Advantageously, the second part is adjacent to the first part.

[0012] In a particular configuration, the second part at least partially overlaps the first part.

[0013] In an advantageous development, the first part of the sample forms a ring around the second part of the sample.

[0014] Preferably, the first projector defines an empty area devoid of patterns. The second projector illuminates the empty area without illuminating the patterns of the first textured light.

[0015] According to one embodiment, the control circuit is configured to simultaneously acquire the images of the first series of images and the second series of images.

[0016] In an advantageous development, the control circuit is connected to at least one shutter configured to alternately block transmission of the first textured light and the second textured light towards the sample holder in the second part to avoid superimposition of the first textured light and the second textured light or the control circuit is configured to alternately emit the first textured light and the second textured light.

[0017] Preferably, the control circuit is configured to acquire at least one image from the second series of images between two images from the first series of images, in a time period.

[0018] The invention also relates to a method of topographic measurement of a sample which more easily performs measurements of coarse deformation and fine deformation.

[0019] This result is to be achieved by means of a topographic measurement method for a sample comprising the following steps: - place a sample on a sample holder; - apply a temperature ramp to the sample; - apply a first textured light to a first part of the sample and a second textured light to a second part of the sample different from the first part of the sample, the second textured light having patterns with a second repetition step lower than a first repetition step of the patterns of the first textured light; - acquire a first series of images of the first textured light applied to the first part of the sample during the temperature ramp; - acquire a second series of images of the second textured light applied to the second part of the sample during the temperature ramp; - process the first series of images and the second series of images to determine a first deformation of the first part and a second deformation of the second part during the temperature ramp.

[0020] In a preferred development, the second part is included in the first part. The first deformation is subtracted from the second deformation. Summary description of the drawings

[0021] Other advantages and features will become clearer from the following description of particular embodiments and implementations of the invention given by way of non-limiting examples and shown in the accompanying drawings, in which:

[0022] [Fig-1]: [Fig.1] schematically illustrates one embodiment of a device topographic measurement according to the invention;

[0023] [Fig.2] : [Fig.2] schematically illustrates a top view of a sample subjected to two different textured lights;

[0024] [Fig.3] : [Fig.3] schematically illustrates a top view of a sample subjected to two different textured lights;

[0025] [Fig.4] : [Fig.4] schematically illustrates a top view of a sample subjected to the first textured light which is able to cover second parts of the sample shown in dotted line;

[0026] [Fig.5] : [Fig.5] schematically illustrates a top view of a sample subjected to the first textured light which defines empty areas delimiting second parts of the sample illustrated in dotted lines;

[0027] [Fig.6] : [Fig.6] schematically illustrates a top view of a sample subjected to the second textured light delimiting second parts of the sample, the first part being illustrated in dotted line. Description of the implementation methods

[0028] Fig. 1 illustrates a topographic measuring device which has a sample holder 1 for supporting a sample 2. The topographic measuring device also includes a first projector 3 for applying a first textured light 4 to at least a first part 2a of the sample 2 and a second projector 5 for applying a second textured light 6 to at least a second part 2b of the sample 2. The second part 2b is different from the first part 2a.

[0029] The sample holder 1 has a first face intended to receive the sample 2. The Z direction is normal to the first face.

[0030] Each of the first textured light 4 and the second textured light 6 defines several repeating patterns, for example, several fringes. The surface lighting Sample 2 is produced by the first projector 3 and the second projector 5. The textured light can be an image in shades of gray or in shades of other colors, and possibly in black and white. The textured light defines patterns that repeat with a predefined frequency and phase. The projectors are projection devices configured to project textured light, preferably in the visible spectrum.

[0031] Textured light advantageously forms a fringe pattern, for example, of the moiré or "shadow moiré" type. In one embodiment, the projector directly emits a fringe pattern. In another embodiment, the textured light is formed by means of a mask through which the light from the projector passes. The mask has openings and opaque areas, for example, in the form of a Ronchi grid. It is also possible to combine these two techniques.

[0032] Predefined patterns are applied to the surface of the sample, and the topography of the sample will modify the shape of the applied patterns. By analyzing the changes in the shape of the patterns, it is possible to calculate the three-dimensional deformation of the sample.

[0033] The topographic measurement device includes a first camera 7 for observing the first textured light 4 applied to the first part 2a of the sample 2 to acquire at least a first series of images 8 and a second camera 9 for observing the second textured light 5 applied to the second part 2b of the sample 2 to acquire at least a second series of images 10. The second camera 9 is different from the first camera 7. Alternatively, the first camera 7 and the second camera 9 share the same capture sensor, but the image comes from two different paths by means of lenses and / or prisms so as to observe two different portions of the sample 2 placed on the sample holder 1.

[0034] The first camera 7 and the second camera 9 are image capture means configured to acquire series of images of the surface of the sample 2. The first camera 7 and the second camera 9 are arranged to capture the textured light applied to the surface of the sample 2. Preferably, the optical axis of the first camera 7 and the second camera 9 is parallel to the Z direction normal to the surface of the sample holder 1 or has a small offset from the Z direction.

[0035] Each camera acquires a series of images. The images of each series are compared with each other or with a reference, to observe the deformations of the textured lights and deduce the deformations of sample 2.

[0036] The images are sent to a computing circuit A configured to calculate the deformations between the images and to calculate the three-dimensional deformation of the sample 2.

[0037] The topographic measurement device includes a control circuit 16 connected to the first projector 3, the second projector 5, the first camera 7, and the second camera 9. The control circuit 16 is configured so that the second textured light 6 has patterns with a second repetition interval that is smaller than the first repetition interval of the patterns of the first textured light 4. Because the second textured light 6 has patterns with a second repetition interval that is smaller than the first repetition interval of the patterns of the first textured light 4, the second textured light 6 can measure finer deformations than the first textured light 4.

[0038] During the deformation of sample 2, the first camera 7 acquires a series of images of the first part 2a of sample 2, onto which the first textured light 4 is applied with the first repetition interval. To measure the relevant information, the resolution of the first camera 7 is adapted to the surface area of ​​the first part 2a and to the amount of information provided by the first textured light 4. The larger the surface area of ​​the first part 2a, the greater the amount of information to be processed. The greater the repetition interval of the first textured light 4, the greater the amount of information to be processed. The performance of the first camera 7 defines the relationship between the surface area of ​​the first part and the repetition interval of the first textured light 4. It is advantageous for the first camera 7 to have adjustable magnification in order to adapt the measurement performance to the requirements.Preferably, the first projector 3 is equipped with a magnification means, for example a plurality of movable lenses, which is configured to increase or decrease the magnification of the repetition step of the first textured light 4. Preferably, the repetition step is adapted to the extent of the surface of the first part 2a and / or to the desired measurement resolution. Alternatively, the first projector 3 is capable of delivering different first textured lights 4 with different repetition steps.

[0039] During the deformation of sample 2, the second camera 9 acquires a series of images of the second part 2b of sample 2, onto which the second textured light 6 is applied with the second repetition step. The resolution of the second camera 9 is adapted to the definition provided by the second textured light 6 and to the size of the second part 2b in order to measure the relevant information. It is advantageous for the second camera 9 to have adjustable magnification so as to adjust the measurement performance to the requirements. Preferably, the second projector 5 is equipped with a magnification means, for example, a plurality of movable lenses, which are configured to increase or decrease the magnification of the repetition interval of the second textured light 6. Preferably, the repetition interval is adapted to the surface area of ​​the second part 2b and / or the desired measurement resolution. Alternatively, the second projector 5 is capable of delivering different first textured lights 4 with different repetition intervals.

[0040] Since the second repetition step is smaller than the first repetition step, it is advantageous for the resolution of the second camera 9 to be greater than the resolution of the first camera 7. Preferably, the magnification of the second camera 9 is greater than the magnification of the first camera 7 during the deformation measurement, if the sensors of both cameras have the same resolution. For example, the first camera 7 and the second camera 9 are identical, and the adaptation of the resolution of the images taken by the two cameras is defined by the magnification of the lens positioned upstream of the sensor along the optical path.

[0041] The topographic measuring device includes heating means 12 and / or cooling means 13 that are connected to the control circuit 16. The heating means 12 and / or cooling means 13 are arranged to heat or cool the sample 2 so that the sample 2 follows a predefined temperature profile. Preferably, the heating means 12 include infrared radiant heating. Advantageously, the cooling means 13 include the application of a fluid that circulates in the sample holder 1 or is in direct contact with the sample holder 1. Depending on the requirements, the fluid may be a gas or a liquid. The nature of the fluid depends on the minimum temperature of the sample holder 1 that is to be achieved.

[0042] The control circuit 16 applies a temperature ramp to sample 2. During the temperature ramp, the temperature of sample 2 changes and sample 2 deforms. During the temperature ramp, the first textured light 4 is applied to the first part 2a of sample 2 and the second textured light 6 is applied to the second part 2b of sample 2. During the temperature ramp, the first series of images 8 and the second series of images 10 are acquired. The images from the first series of images 8 are used, for example, to measure the deformation of the first part 2a during the temperature ramp. The images from the second series of images 10 are used, for example, to measure the deformation of the second part 2b during the temperature ramp.

[0043] During the same temperature ramp, the second series of images 10 allows for a more precise measurement of the deformation in the second part 2b than the deformation measurement in the first part 2a, which is performed by the first series of images 8. The two series of images are acquired during the same temperature ramp, which allows for a better characterization of the behavior of sample 2 in comparison of two measurements carried out in two ramps at successive temperatures because this avoids an aging effect of sample 2.

[0044] It is particularly advantageous to use the deformation data acquired for the first part 2a to calculate more accurate deformation data for the second part 2b. In order for the deformation data relating to the first part 2a to be as relevant as possible for studying the deformation of the second part 2b, it is preferable that the second part 2b be as close as possible to the first part 2a. Advantageously, the second part 2b is adjacent to the first part 2a, that is, the first part 2a has an interface with the second part 2b.

[0045] Advantageously, at least a portion of the second part 2b is included in the first part 2a. The first part 2a can be considered as a non-convex, non-self-intersecting polygon, for example, a rectangle whose intersection with a smaller rectangle has been removed. The second part 2b encroaches inside the first part 2a. Depending on the configuration, the portion occupied by the second part 2b is measured or not by means of the first textured light 4 and the first camera 7. Preferably, at least 50% of the surface of the second part 2b is included in the surface of the first part 2a. More advantageously, the second part 2b is included in the first part 2a, that is, the first part 2a forms a ring around the second part 2b.

[0046] The application of the first textured light 4 and the application of the second textured light 6 to the first part 2a and the second part 2b can be carried out in different ways. In one scenario, the first textured light 4 and the second textured light 6 are applied simultaneously during the temperature ramp. This embodiment is advantageous when the first camera 7 and the second camera 9 acquire the first series of images 8 and the second series of images 10 simultaneously, respectively.

[0047] When the first part 2a and the second part 2b are slightly offset or share a single interface, it is possible to apply both textured lights simply. When the first part 2a and the second part 2b partially or completely overlap, it is important that the first textured light 4 does not overlap with the second textured light 6. The first textured light 4 will define an empty area, that is, an area without a pattern, which is preferably an unlit area. This empty area corresponds wholly or partially to the second part 2b.

[0048] The empty area may originate from a part of the lighting device of the first projector 3 that is not activated or from a shutter 11 disposed between the first projector 3 and the sample 2 along the optical path. The empty area corresponds Preferably, as closely as possible to the second part 2b. The second textured light 6 is applied in the empty area delimited at least partially by the first textured light 4. A shutter 11 may also be present along the optical path of the second projector 5 to form an empty area, i.e., an area unlit by the second projector 5. Activating and deactivating the shutter 11 allows the extent of the illuminated area to be modified. Preferably, the shutter 11 associated with the first projector 3 operates independently of the shutter 11 of the second projector 5.

[0049] It is advantageous to use an empty area, which is an unlit area, in order to take advantage of greater dynamic range in the definition of patterns, particularly when the patterns are represented in black and white or with shades of gray. Alternatively, the first textured light 4 and the second textured light 6 use different wavelengths, for example, to define different colors, and are projected simultaneously onto their entire respective areas. The first camera 7 or the control circuit 16 selects the first textured light 4 by colorimetric analysis, or preferably by a first optical filter 14. The second camera 9 selects the second textured light 6 by colorimetric analysis, or preferably by a second optical filter 15. The [Fig.Figure 2 illustrates an embodiment where the first part 2a completely surrounds the second part 2b and the two textured lights are applied simultaneously, the second part 2b being arranged inside a ring defined by the first part 2a. Figure 3 illustrates an embodiment where the first part 2a and the second part 2b are adjacent and offset from each other. The interface is in the form of a straight line.

[0050] In a preferred embodiment, the control circuit 16 is configured to simultaneously acquire the images of the first series of images 8 and the second series of images 10 within a time period. The first textured light 4 is applied with a first wavelength, and the second textured light 6 is applied with a second wavelength different from the first wavelength. The control circuit 16 separates the first textured light 4 and the second textured light 6 by colorimetric analysis, or the first camera 7 and the second camera 9 are equipped with optical filters.

[0051] In an alternative embodiment illustrated in Figures 4, 5, and 6, the first textured light 4 is applied alternately with the second textured light 6 during the temperature ramp. This embodiment is advantageous when the second part 2b is included, at least partially, within the first part 2a.

[0052] The first projector 3 and the second projector 5 can respectively apply the first textured light 4 and the second textured light 6 alternately on the first part 2 and the second part 2b. Figures 4 and 5 illustrate the application of the first textured light 4, with the second part 2b shown as a dashed line. Figure 6 illustrates the application of the second textured light 6, with the first part 2a shown as a dashed line.

[0053] Alternatively, at least one shutter 11 is connected to the control circuit 16 and is movable to alternately shutter the first textured light 4 and the second textured light 6, thus alternately illuminating the sample 2. The use of a shutter 11 is particularly advantageous because it can be moved quickly to block at least part of the first textured light 4. This avoids regularly switching the first projector 3 and / or the second projector 5 on and off. The control circuit 16 can be configured so that the same portion of the sample 2 is not simultaneously illuminated by the first textured light 4 and the second textured light 6.

[0054] The alternative application of the first textured light 4 and the second textured light 6 when the first part 2a and the second part 2b overlap and more preferably cover completely allows two different deformations to be measured on the second part 2b.

[0055] The first series of images 8 allows the deformation of the first part 2a to be measured. The second series of images 10 allows the deformation of the second part 2b to be measured. When the second part 2b and the first part 2a overlap, it is advantageous to subtract the overall deformation of the first part 2a from what is measured for the second part 2b in order to determine the specific deformation of the second part 2b. When the first series of images corresponds to a measurement area that is larger than the second series of images, and the first area completely surrounds the second area or overlaps the second area by at least 50% of its surface, it is particularly advantageous to have a first series of images 8 that provides a lower resolution than the second series of images 10, for example, at least 20% lower, in order to limit the amount of information to be processed.

[0056] As an alternative to subtracting deformations, it is possible to compare the deformation of the second part 2b to the deformation of the first part 2a. If the difference between the deformations is less than a threshold value, the layer(s) of the second part 2b are compatible with the layer(s) of the first part 2a. For example, the second part 2b corresponds to all or part of a component placed on a support. The first part 2a extends over the support. Comparing the deformations makes it possible to determine whether the deformation of the component is compatible with the deformation of the support. Alternatively, the second part 2b extends into a hole in the support to determine whether the hole formed in the support modifies the deformation. of the support. For example, the hole formed in the support allows us to compare two different stacks of layers.

[0057] In another alternative, the first series of images 8 is analyzed, and an interpolated topography is calculated on the second part 2b from the measurement of the first part 2a. Then, the interpolated strain measurement of the first part 2a is subtracted from the strain measurement of the second part 2b, in order to analyze only the local strains in the second part 2b. When the second part 2b has a different stacking pattern than the first part 2a, the interpolation makes it possible to estimate the strain component corresponding to the stacking pattern of the first part 2a with respect to the strain calculated from the second series of images 10.

[0058] Preferably, the second part 2b is included in the first part 2a. The first deformation is subtracted from the second deformation, or the first deformation and the second deformation are compared, or an interpolated topography of the second part 2b, which has been calculated from the first deformation, is subtracted from the first deformation to calculate the local deformations of the second part 2b.

[0059] The control circuit 16 comprises one or more processors and one or more memories for storing information. The control circuit 16 may be included in a computer.

[0060] It is particularly advantageous for the images of the first series of images 8 to be acquired simultaneously with the images of the second series of images 10, that is, at the same instant or almost at the same instant, so that two images are representative of the same deformation state. The use of two projectors and two cameras allows for faster measurement than a single projector applying two different sets of textured lights and / or a camera performing two separate acquisitions. By adapting the resolution of the image taken by the camera to the resolution of the textured light pattern provided by the projector, the amount of relevant data delivered by the camera is improved. This avoids providing insufficiently precise data because the camera is not sufficiently efficient with respect to textured light, and it prevents saturating the control circuit 16 with unnecessary data because the textured light has a pitch that is too coarse.

[0061] Preferably, the two projectors are mounted to move relative to the sample holder 1. In one embodiment, the two projectors are mounted to move along the X and Y directions, and the sample holder 1 is mounted to remain stationary along these two directions. In another embodiment, the two projectors are mounted to remain stationary along the X and Y directions, and the sample holder 1 is mounted to move along these two directions. In a final embodiment, the two projectors are The two projectors are mounted movably along the X and Y directions, and the sample holder 1 is also mounted movably along these two directions. The two projectors can be mounted independently of each other along the X and / or Y directions. The X and Y directions are perpendicular to each other and perpendicular to the Z direction.

[0062] It is also possible to provide that the first camera 7 and / or the second camera 9 are mounted movable relative to the sample holder 1 in the X and Y directions.

[0063] Alternatively or in addition, the control circuit 16 is also configured to move the first part 2a along the sample 2 during deformation to calculate the deformation of a surface at least twice the area of ​​the first part 2a, preferably to calculate the deformation of a surface greater than 80% of the area of ​​sample 2. More preferably, the control circuit 16 is configured so that the first projector 3 and the second projector 5 apply a first textured light 4 and a second textured light 6 that have the same repetition interval. It is advantageous for the control circuit to move both projectors and both cameras so that the first part 2a and the second part 2b move independently of each other in order to characterize at least 80% of the area of ​​sample 2.By using two separate pairs of projectors and cameras, it is possible to measure the surface of sample 2 twice as fast.

Claims

1. Demands Topographic surveying device comprising: - a sample holder (1) intended to receive a sample (2); - a first projector (3) intended to apply a first textured light (4) on at least a first part (2a) of the sample (2); - a second projector (5) intended to apply a second textured light (6) to at least a second part (2b) of the sample (2), the second part (2b) being different from the first part (2a); - a first camera (7) intended to observe the first textured light (4) applied to the first part (2a) of the sample (2) to acquire a first series of images (8); - a second camera (9) intended to observe the second textured light (6) applied to the second part (2b) of the sample (2) to acquire a second series of images (10); - heating (12) and / or cooling (13) means configured to heat or cool the sample (2); - a control circuit (16) connected to the first projector (3), the second projector (5), the first camera (7) and the second camera (9), the control circuit (16) being configured so that the second textured light (6) has patterns with a second repetition step lower than a first repetition step of the patterns of the first textured light (4); in which the control circuit (16) is connected to the heating (12) and / or cooling (13) means to apply a temperature ramp to the sample (2); in which the control circuit (16) compares the images of the first series of images with each other or with a reference to deduce a deformation of the first part and compares the images of the second series of images with each other or with a reference to deduce a deformation of the second part; in which, during the temperature ramp, the first textured light (4) is applied to the first part (2a) of the sample (2) and the second textured light (6) is applied to the second part (2b) of the sample (2) and the images of the first series of images (8) and the images of the second series of images (10) are acquired simultaneously in a period of time; in which the second part (2b) is adjacent to the first part (2a).

2. Topographic measuring device according to claim 1 in which the second part (2b) at least partially overlaps the first part (2a).

3. Topographic measuring device according to claim 2 in which the first part (2a) of the sample (2) forms a ring around the second part (2b) of the sample (2).

4. Topographic measuring device according to claim 3 wherein the first projector (3) defines an empty area devoid of patterns and wherein the second projector (5) illuminates the empty area without illuminating the patterns of the first textured light.

5. Topographic measuring device according to any one of claims 1 to 4 wherein the control circuit (16) is configured so that the first textured light and the second textured light are applied simultaneously.

6. Topographic measurement device according to claim 5 wherein the first textured light (4) is applied with a first wavelength and the second textured light (6) is applied with a second wavelength different from the first wavelength and wherein the control circuit (16) separates the first textured light (4) and the second textured light (6) by colorimetric analysis or the first camera (7) and the second camera (9) are provided with optical filters.

7. Topographic measuring device according to claim 2 or 3 wherein the control circuit (16) is connected to at least one shutter (11) configured to alternately block transmission of the first textured light (4) and the second textured light (6) towards the sample holder (1) in the second part (2b) to avoid overlap of the first textured light (4) and the second textured light (6) or wherein the control circuit (16) is configured to alternately emit the first textured light (4) and the second textured light (6).

8. Topographic measuring device according to claim 7 in which the control circuit (16) is configured to acquire at minus one image from the second series of images (10) between two images from the first series of images (8) in a period of time.

9. A method for topographically measuring a sample (2) comprising the following steps: - placing a sample (2) on a sample holder (1); - applying a temperature ramp to the sample (2); - applying a first textured light (4) to a first part (2a) of the sample (2) and a second textured light (6) to a second part (2b) of the sample (2) different from the first part (2a) of the sample (2), the second textured light (6) having patterns with a second repetition step smaller than the first repetition step of the patterns of the first textured light (4); - acquiring a first series of images (8) of the first textured light (4) applied to the first part (2a) of the sample (2) during the temperature ramp;- acquire a second series of images (10) of the second textured light (6) applied to the second part (2b) of the sample (2) during the temperature ramp, the images of the first series of images (8) and the images of the second series of images (10) being acquired simultaneously in a period of time; - process the first series of images (8) and the second series of images (10) to determine a first deformation of the first part (2a) and a second deformation of the second part (2b) during the temperature ramp, the images of the first series of images being compared with each other or with a reference to deduce a deformation of the first part and the images of the second series of images being compared with each other or with a reference to deduce a deformation of the second part.

10. A method for topographically measuring a sample (2) according to claim 9 wherein the second part (2b) is included in the first part (2a) and wherein the first strain is subtracted from the second strain or wherein the first strain and the second strain are compared or wherein an interpolated topography of the second part (2b) which has been calculated from the first strain is subtracted from the first strain to calculate the local strains of the second part (2b).

Images