3D sensor

Abstract

The invention relates to the field of optical displacement sensors for measuring the three-dimensional shape of the surface of a measurement object. The optical sensor of the invention is configured to project measurement light into a plurality of discrete measurement regions via a first lens component with longitudinal chromatic dispersion, receive measurement light reflected from the intersection of the measurement object with one or more of the plurality of measurement regions and focus the received measurement light onto the surface of a diffractive or non-specular reflective component, and image measurement light diffracted or reflected from the diffractive or non-specular reflective component onto an active surface of a photodetector via a chromatically dispersive optical assembly and a mask. The position on the active surface of the photodetector at which measurement light is in focus depends on which measurement region of the plurality of measurement regions the measurement light was reflected from and the position within said measurement region from which the measurement light was reflected.

Description

[0001] 3D SENSOR

[0002] Technical Field

[0003] The invention relates to the field of optical displacement sensors for measuring the three- dimensional shape of the surface of a measurement object.

[0004] Background

[0005] Prior art optical sensor for measuring the three-dimensional shape of a measurement object may have a limited range over which variation in the height of the surface of the object can be sensed. Optical sensors that use longitudinal chromatic dispersion for the distance measurement require optics having either large longitudinal chromatic aberration or a large wavelength band for providing long measurement range. They may have separate axes for illumination and measurement, which leads to shadowing of the measurement light by high aspect ratio features and may not be compatible with sloped surfaces. They often require that the average angle of incidence of light onto a photodetector is relatively large, thereby decreasing the effectiveness of the photodetector.

[0006] Summary of the Invention

[0007] According to a first aspect of the invention, an optical sensor for measuring the displacement of a measurement object relative to the sensor is provided. The optical sensor is configured to

[0008] • project measurement light into a plurality of discrete measurement regions via a first lens component, wherein each of the plurality of measurement regions is located at a different position relative to the first lens component such that each measurement region at least partially overlaps at least one other measurement region in a longitudinal direction measured parallel to the optical axis of the first lens component, and wherein measurement light is chromatically dispersed across the longitudinal direction within each measurement region;

[0009] • receive measurement light reflected from the intersection of the measurement object with one or more of the plurality of measurement regions and focus the received measurement light onto the surface of a diffractive or non-specular reflective component; and

[0010] • image measurement light diffracted or reflected from the diffractive or non-specular reflective component onto an active surface of a photodetector via a chromatically dispersive optical assembly and a mask such that: o the position on the active surface of the photodetector at which measurement light is in focus depends on which measurement region of the plurality of measurement regions the measurement light was reflected from and the position within said measurement region from which the measurement light was reflected, and o measurement light reflected from outside one of the plurality of measurement regions or measurement light not in focus at the point of reflection is at least partially blocked from reaching the photodetector by the mask.

[0011] The plurality of measurement regions may be non-overlapping in a lateral direction measured perpendicular to the optical axis of the first lens component.

[0012] The optical sensor may be configured to project measurement light into the plurality of measurement regions from a light source comprising a plurality of light emitting areas, and each light emitting area may emit measurement light that is projected into a single measurement region.

[0013] The optical sensor may be configured to project measurement light into the plurality of measurement regions from the light source via the first lens component, and the plurality of light emitting areas may be located relative to the first lens component such that each light emitting area is located at a different longitudinal position measured parallel to the optical axis of the first lens component and at a different lateral position measured perpendicular to the optical axis of the first lens component.

[0014] The optical sensor may be configured to project measurement light into the plurality of measurement regions from the light source via the first lens component and a second lens component, and the plurality of light emitting areas may be located relative to the second lens component such that each light emitting area is located at a different longitudinal position measured parallel to the optical axis of the second lens component and at a different lateral position measured perpendicular to the optical axis of the second lens component.

[0015] The light source may comprise a single light emitting component and a first mask, wherein the first mask is configured to divide the light emitting component into the plurality of light emitting areas by partially blocking light emitted by the light emitting component. The light emitting component may be an array of light emitting diodes.

[0016] The light source comprises a plurality of light emitting components, where each light emitting area is provided by one or more of the plurality of light emitting components.

[0017] The plurality of light emitting regions may be slit-shaped.

[0018] Measurement light reflected from one or more of the plurality of measurement regions may be received by the first lens component and focused onto a diffractive or non-specular reflective component by a third lens component.

[0019] The first lens component may causes longitudinal chromatic dispersion of light passing through the lens and / or the second lens component and third lens component may cause longitudinal chromatic dispersion of light passing through each of the second and third lens components.

[0020] The focal length of the second lens component may be different to the focal length of the third lens component.

[0021] All wavelengths of measurement light reflected from a given measurement region may be focused at the same distance from the third lens component on the diffractive or non-specular reflective component.

[0022] The optical sensor may comprise a second mask, where the second mask is positioned between the diffractive or non-specular reflective component and the photodetector such that focused measurement light reflected from the plurality of measurement regions is allowed to pass and measurement light reflected from outside of the plurality of measurement regions or measurement light not in focus at the point of reflection from the measurement object is at least partially blocked from reaching the photodetector.

[0023] The second mask may be located on the surface of the diffractive or non-specular reflective component. The second mask may be located at an image plane of the diffractive or non-specular reflective component formed by a further lens component positioned in the path of measurement light between the diffractive or non-specular reflective component and the photodetector.

[0024] The photodetector may be oriented such that the angle between the normal to the active surface of the photodetector and the output optical axis of the chromatically dispersive optical assembly is less than 5, 10 or 25 degrees.

[0025] The optical sensor may be configured to receive measurement light reflected from one or more of the plurality of measurement regions through the first lens component.

[0026] According to a second aspect of the invention, a method for determining a three-dimensional shape of a measurement object using the optical sensor of any preceding claim is provided. The method comprises:

[0027] • measuring a first set of three-dimensional coordinates from which focused measurement light is reflected from the surface of the measurement object at the intersection of the measurement object and one or more of the plurality of measurement regions;

[0028] • displacing the measurement object with respect to the optical sensor by a known displacement;

[0029] • measuring a second set of three-dimensional coordinates from which focused measurement light is reflected from the surface of the measurement object,

[0030] • determining the three-dimensional shape of the measurement object based on the first set of three-dimensional coordinates, the second set of three-dimensional coordinates, and the known displacement of the measurement object between the measurements of the first set of three-dimensional coordinates and the second set of three-dimensional coordinates.

[0031] The method may further comprise:

[0032] • displacing the measurement object with respect to the optical sensor by a second known displacement;

[0033] • measuring a third set of three-dimensional coordinates from which focused measurement light is reflected from the surface of the measurement object; and determining the three-dimensional shape of the measurement object may be further based on the third set of three-dimensional coordinates and the known second displacement.

[0034] Brief Description of the Drawings

[0035] Figure 1 is a schematic diagram of an optical sensor according to the present invention.

[0036] Figure 2 depicts the light source 101 and measurement regions 104a-c of the sensor 100 in more detail.

[0037] Figures 3Aand 3B depict measurement light projected onto the photodetector 109 of sensor 100.

[0038] Figure 4 depicts an alternative embodiment of an optical sensor according to the invention.

[0039] Figure 5 depicts a method for determining the three-dimensional shape of a measurement object using the sensor of the present invention.

[0040] Detailed Description of the Invention

[0041] Figure 1 is a schematic diagram of an optical sensor according to the present invention. The optical sensor is a sensor for measuring the displacement of a measurement object 120 relative to the sensor, and / or for measuring the 2D profile of the measurement object 120.

[0042] Measurement light is emitted from a light source 101 into a plurality of measurement regions 104a-c via a first lens component 103. Each of the plurality of measurement regions 104a-c is located at a different position relative to the first lens component 103 such that each measurement region at least partially overlaps at least one other measurement region in a longitudinal direction measured parallel to the optical axis of the first lens component, i.e. parallel to the Z-axis as shown in Figure 1. Measurement region 104a is located furthest away from first lens component 103 and partially overlaps measurement region 104b in this longitudinal, i.e. Z-axis, direction. Measurement region 104b partially overlaps both measurement regions 104a and 104c in the longitudinal direction. Measurement region 104c is located closest to the first lens component 103 and partially overlaps measurement region 104b in the longitudinal direction. In one embodiment, the first lens component 103 causes longitudinal chromatic dispersion of measurement light that passes through it, i.e. parallel beams of light having different wavelengths are focused at different distances from the first lens component 103, measured parallel to the optical axis of the first lens component 103, depending on their wavelength. Therefore, within each measurement region 104a-c, measurement light is chromatically dispersed across the longitudinal direction such that a different wavelength of light is in focus at each position along the longitudinal direction. In other embodiments, longitudinal chromatic dispersion of measurement light across each measurement region 104a-c may be achieved by other optical components of the sensor 100 instead of or in addition to first lens 103.

[0043] The measurement regions 104a-c preferably extend along a direction perpendicular to the optical axis of the first lens component 103, i.e. parallel to the X-axis as shown in Figure 1. By projecting measurement light into measurement regions 104a-c that extend parallel to the X- axis, the 2D profile of the measurement object 120 can be sensed. However, it is also possible for the X-axis dimension of the measurement regions 104a-c to be arbitrarily small, in which case the sensor can still measure the displacement at one or more points on the surface of the measurement object 120.

[0044] While Figure 1 shows three measurement regions, it will be appreciated that any arbitrary number of measurement regions may be used in an optical sensor according to the present invention, limited only by the physical constraints of the system, not by the principles of the invention. A more detailed discussion of the light source 101 and measurement regions 104a- c is provided below with respect to Figure 2.

[0045] In use, measurement light projected within the measurement regions 104a-c is reflected (i.e. scattered) from the surface of a measurement object 120. In particular, focused measurement light is reflected from the surface of the measurement object 120 at any intersections of the surface of the measurement object and one or more measurement regions 104a-c. The wavelength of focused measurement light reflected from the surface of the measurement light depends on the displacement of the surface of the measurement object relative to the sensor, i.e. on the longitudinal position of the intersection within the / each measurement region 104a- c. Some of the measurement light reflected from the surface of the measurement object is received by the first lens 103 and is focused onto the surface of a diffractive or non-specular reflective component 107, e.g. a diffraction grating or diffusely reflective / scattering surface. In the embodiment depicted in Figure 1 , beam splitter 105 directs measurement light reflected from the surface of the measurement object 120 and received by first lens component 103 towards a third lens component 106, which focuses the reflected measurement light onto the surface of the diffractive or non-specular reflective component 107. It will be appreciated that other arrangements than that depicted in Figure 1 may be used, e.g. the locations of the light source 101 and diffractive or non-specular reflective component 107 may be swapped, or other components than beam splitters may be used to enable the projection of measurement light and receipt of reflected measurement light via the first lens component 103.

[0046] The diffractive or non-specular reflective element is aligned at an angle relative to the optical axis of the third lens component 106 that ensures that measurement light reflected from all of the measurement regions is focused onto the surface of the diffractive of non-specular reflective component 107 by the third lens component 106. Measurement light is diffracted or reflected from the diffractive or non-specular reflective component 107 and imaged onto an active surface of a photodetector 109 via a chromatically dispersive optical assembly 108. Use of a diffractive component, e.g. a reflective diffraction grating, as the diffractive or non- specular reflective component 107 is preferable because the properties of the diffractive component can be selected such that a relatively large proportion of the measurement light incident on the diffractive component is diffracted towards the chromatically dispersive optical assembly 108. However, a non-specular reflective, i.e. scattering, component can alternatively be used, since part of the measurement light incident on the surface of the diffractive or non-specular reflective component is reflected (scattered) towards the chromatically dispersive optical assembly 108. The use of the diffractive or non-specular reflective component 107 enables the photodetector 109 to be oriented at or close to perpendicular to the output optical axis of the chromatically dispersive optical assembly 108, i.e. the optical axis of lens 108e. This enables a smaller angle of incidence of light on the active surface of the photodetector, improving the sensitivity of the photodetector 109 compared to a large angle of incidence.

[0047] In the embodiment of Figure 1 , the chromatically dispersive optical assembly 108 includes a lens 108a configured to form an image of the surface of the diffractive or non-specular reflective component 107 in a first image plane, which is aligned with mask 108b. Mask 108b includes a plurality of transmissive regions and opaque regions, and is arranged such that focused measurement light reflected from within the measurement regions is allowed to pass through the transmissive regions and measurement light reflected from outside of the plurality of measurement regions or measurement light not in focus at the point of reflection from the measurement object 120 is at least partially blocked from reaching the photodetector by the opaque regions. In a preferred embodiment the transmissive regions are narrow slits, having a width of e.g. 20 pm; the distance between the transmissive regions is much larger than the width of these slits. For example, the distance between slits may be at least two times, at least three times, at least four times, at least five times, or at least ten times the width of the slits. Measurement light passing through the mask 108b is then chromatically dispersed by the assembly formed by lens 108c, prism 108d and lens 108e. The chromatic dispersion caused by the assembly 108c-e is preferably purely lateral chromatic dispersion, i.e. parallel beams of light having different wavelengths are focused at different distances from the optical axis of lens 108e, measured perpendicular to the optical axis of the lens 108e, depending on their wavelength.

[0048] Optical assembly 108 focuses measurement light onto the active surface of the photodetector 109 such that the position on the active surface of the photodetector at which measurement light is in focus depends on the measurement region from which the measurement light was reflected and the position within the measurement region from which the measurement light was reflected. Therefore, the displacement of the measurement object 120 relative to the sensor 100 and / or the 2D profile of the measurement object 120 can be determined from the light incident on the photodetector based on the position of one or more peaks in the intensity of light measured by the photodetector 109. This is depicted and described in more detail with respect to Figures 3A and 3B.

[0049] Figure 2 depicts the light source 101 and measurement regions 104a-c of the sensor 100 in more detail. In the embodiment depicted in Figures 1 and 2, light source 101 includes light emitting regions 101a-c, which are formed by a light emitting component 101 d, a diffuser 101 e, and a mask 101f. The light emitting areas 101a-c are defined by openings in the mask 101f through which light from the light emitting component 101 d and diffuser 101e can pass. The mask 101 f is made of an opaque material that blocks light from the light emitting component 101 d outside of the light emitting areas 101a-c. The mask 101f may be a single unitary component or may be made up of multiple separate opaque components. Preferably, the mask 101 f comprises a series of opaque lines defining slits between the opaque lines, which form the light emitting areas 101a-c. The light emitting component 101 d may be an array of light emitting diodes, for example. The diffuser 101e improves the uniformity of light emitted by the array of light emitting diodes. The use of the diffuser is optional, i.e. some implementation forms of the invention do not need this diffuser. The needed homogeneity of the light illumination could also be achieved by using e.g. light intensity homogenizing pipes or for example with an array of light fibres.

[0050] Each light emitting area 101 a-c corresponds to one of the measurement regions 104a-c in that in the ideal situation, light emitted from each light emitting area 101a-c is projected into a single measurement region 104a-c. Measurement light is projected into the plurality of measurement regions 104a-c from the light source via the first lens component 103 and a second lens component 102. Each light emitting area 101a-c is located at a different longitudinal position measured parallel to the optical axis of the second lens component 102, i.e. at a different Z-axis position, and at a different lateral position measured perpendicular to the optical axis of the second lens component, i.e. at a different Y-axis position. Where the measurement regions 104a-c extend along the X-axis direction, as described above with respect to Figure 1 , the light emitting areas 101a-c may also extend along the X-axis direction. Preferably the X-axis position of all light emitting areas is the same.

[0051] In Figure 1 , as well as Figures 2 and 4 described below, three lenses 102, 103, 106 are shown for focusing and dispersing measurement light within the measurement regions 104a-c and onto the surface of diffractive or non-specular reflective component 107. However, the invention may be implemented with only first lens 103, which focuses and disperses measurement light into the measurement regions and focuses measurement light reflected from the measurement regions onto the diffractive or non-specular reflective element 107. A configuration using more than one lens, i.e. a combination of first lens 103 and second lens

[0052] 102, or first lens 103 and third lens 106, or all three lens 102, 103 and 106, enables the light source 101 and diffractive or non-specular component 107 to be positioned at different distances from the first lens 103.

[0053] In Figure 2, measurement light emitted from light emitting area 101a is projected into measurement region 104a via the second lens component 102 and the first lens component

[0054] 103. As discussed above, one or both of the first lens component 103 and second lens component 102 cause longitudinal chromatic dispersion of light passing through. Therefore, the ideal point or thin line of light emitting from light emitting region 101 a is chromatically dispersed over the measurement region 104a, with one wavelength of light in focus at the “top” of measurement region 104a (i.e. the end closest to the first lens component 103) and another in focus at the “bottom” of the measurement region 104a (i.e. the end furthest from the first lens component 103) and a continuous spectrum of measurement light focused at points in between. The same pattern is repeated for the light emitting area 101 b and the measurement region 104b, and for the light emitting area 101c and the measurement region 104c.

[0055] The relative arrangement of the measurement regions 104a-c is defined by the relative arrangement of the light emitting areas 101a-c. The Z-axis height of the measurement regions 104a-c is defined by the used spectrum of measurement light emitting from the light emitting areas 101a-c and the dispersive properties of the lens. The arrangement of the light emitting areas 101a-c and the spectrum and dispersive properties of the lens are preferably selected so that every measurement region 104a-c overlaps at least one other measurement region along the Z-axis in order to provide complete coverage of the Z-axis range. In theory it may be possible to have non-overlapping ranges that are either very closely spaced or essentially adjacent along the Z-axis, but in practice this is likely to leave some gaps in the Z-axis range for which height cannot be measured if the surface of the measurement object traverses the measurement regions in a direction perpendicular to the Z-axis. In general, the direction of traversal of the measurement object through the measurement regions is selected such that each point to be measured on the surface of the measurement object passes through at least one of the measurement regions 104a-c when traversing through the total measurement area. Therefore, the usable total Z-measurement range can be changed by changing the angle in which the surface is traversing compared to the optical axis of the first lens 103.

[0056] In one example, the mask 101f defines 30 slits of width 10 pm with slit-to-slit separation of 373 pm and if the light source 101 and mask 101f are arranged at an angle of 60 degrees to the optical axis of the second lens component 102, i.e. the Z-axis, and the second lens component 102 and first lens component 101 have magnification power of 1. The used spectrum of measurement light is 420 to 460 nm and the dispersive power of the first lens is 8.75 pm / nm. In this case, there are 30 measurement regions, each of which extends 350 pm parallel to the optical axis of the first lens component 103, i.e. parallel to the Z-axis, the spacing of the measurement regions parallel to the Y-axis is 187 pm, and the total Z-axis range covered by all of the measurement regions is 9.7mm. The use of multiple measurement regions to cover a large Z-range enable a relatively small wavelength range to be used for the measurement light, which means that higher-power narrowband light sources may be used, e.g. blue LEDs. Furthermore, the use of an array of LEDs allows for homogeneous optical power distribution over the measurement range.

[0057] Other configurations for the light source than that described above including a single light emitting component 101 d, diffuser 101e and mask 101f may be used, provided that a plurality of light emitting areas are provided in the same arrangement as described above. For example, each light emitting area may be provided by an independent light emitting component, in which case separate masks or even no mask may be required for each light emitting component.

[0058] In the simplest embodiment, only the first lens component 103 causes longitudinal chromatic dispersion of measurement light passing through it. In this way, measurement light projected into the measurement regions 104a-c is dispersed and measurement light reflected from the measurement regions is inversely dispersed, i.e. converges, by the first lens component 103 before being focused onto the diffractive or non-specular reflective component 107. However, other arrangements are possible as long as measurement light is dispersed across the measurement regions and reconverged before being focused onto the diffractive or non- specular reflective component 107, i.e. such that all wavelengths of measurement light reflected from a given measurement region are focused at the same distance from the third lens component 106 on the diffractive or non-specular reflective component 107.

[0059] Figures 3Aand 3B depict measurement light projected onto the photodetector 109 of sensor 100. Figure 3A depicts the regions 110a-c on the active surface of the photodetector 109 onto which measurement light reflected from each measurement region 104a-c is projected.

[0060] Measurement light incident in each region 110a-c on the active surface of the photodetector is reflected from a single different measurement region 104a-c, e.g. measurement light incident in region 110a was reflected from measurement region 104a, measurement light incident in region 110b was reflected from measurement region 104b, and measurement light incident in region 110c was reflected from measurement region 104c. As described above, the chromatically dispersive optical assembly 108 of the sensor 100 laterally disperses the wavelengths of light from each measurement region 104a-c across the active surface of the photodetector 109. The reflected measurement light is therefore dispersed across a direction parallel to line A-B shown in Figure 3A. Figure 3B shows an exemplary intensity profile taken along the line A-B. A clear intensity peak 111 is visible in the intensity profile. The position of the intensity peak corresponds to the position along the line A-B on the surface of the photodetector 109 where light is sensed with the highest intensity. The line A-B corresponds to a constant X-axis position within the measurement regions 104a- c. From the position of the intensity peak along the line A-B, it can be determined a) which region 110a-c the intensity peak lies in and b) the wavelength of the intensity peak. From the determined region 110a-c, the corresponding measurement region can be identified, and from the determined wavelength, the corresponding Z-axis position within the identified measurement region can be determined. Since the Z-axis and Y-axis positions of each measurement region are known, the Z-axis and Y-axis position of the surface of the measurement object can be determined for each X-axis position defined by line A-B or similar lines at other X-axis positions.

[0061] In practice, it is not necessary to explicitly determine the wavelength of the intensity peak since it is possible to define a function that maps the position within the region 110a-c to a position within the measurement region 104a-c without always performing an intermediate step of determining the wavelength.

[0062] In use, multiple peaks may be observed for a given X-axis position, e.g. along a line A-B, since the measurement regions are distributed in the Y-direction. The Z-axis and Y-axis position of every intensity peak is determined. By scanning the measurement regions across the surface of the measurement object, e.g. by moving the measurement object along a conveyor relative to the sensor 100, the 2D profile of the measurement object along the Y- axis, or the 3D shape of the surface of the measurement object, can be reconstructed from the Z-axis and Y-axis positions determined from the intensity peaks of reflected measurement light, i.e. the Z-axis positions are determined from the locations of detected intensity peaks at the photodetector and the Y-axis positions are determined based on a geometrical mapping derived from the known movement or displacement of the measurement object along the Y- axis. As explained above, the direction of traversal of the measurement object through the measurement regions is selected such that each point to be measured on the surface of the measurement object passes through at least one of the measurement regions 104a-c when traversing through the total measurement area.

[0063] The use of two masks, one in the illumination part and another in the corresponding position in the imaging party results in sharp intensity peaks, improving the accuracy and Z-axis resolution of the sensor. The use of two masks also improves the resolution / accuracy in the X-axis as the line projected onto the sensor is more localised along this axis.

[0064] Figure 4 depicts an alternative embodiment of the invention in which the mask 108b of sensor 100 is replaced by a mask 408b which is overlaid on the diffractive or non-specular reflective component 407. With the placement of the mask 408b directly onto the surface of the diffractive or non-specular reflective element, lens 108a is no longer required to form the image plane with which mask 108b is aligned in sensor 100. The sensor 400 requires fewer components than sensor 100 and is therefore simpler to calibrate.

[0065] Figure 5 depicts a method 500 for determining the three-dimensional shape of a measurement object using the sensor 100 or 400 of the present invention. At step 501 , measurement light is projected into the measurement regions as described above. At step 502, measurement light reflected from the measurement regions is sensed as described above. At step 503, a set of three-dimensional coordinates are determined, i.e. measured, as described above. At step 504, the measurement object is displaced with respect to the optical sensor by a known displacement, i.e. by moving the sensor relative to the measurement object or vice versa. At step 505, a further set of three-dimensional coordinates are determined at the new position. At step 506, the sets of three-dimensional coordinates and known displacement of the measurement object or sensor between the measurements of the coordinates are used to determine the three-dimensional shape of the measurement object. Steps 504 and 505 may be repeated as often as necessary to obtain coordinate data covering the whole measurement object or area of interest, and all sets of coordinates and known displacements are used in the calculation of the 3D shape. The displacement between sets of coordinates may be selected based on the required resolution of the resulting 3D model.

Claims

Claims1 . An optical sensor for measuring the displacement of a measurement object relative to the sensor, the optical sensor configured to: project measurement light into a plurality of discrete measurement regions via a first lens component, wherein each of the plurality of measurement regions is located at a different position relative to the first lens component such that each measurement region at least partially overlaps at least one other measurement region in a longitudinal direction measured parallel to the optical axis of the first lens component, and wherein measurement light is chromatically dispersed across the longitudinal direction within each measurement region; receive measurement light reflected from the intersection of the measurement object with one or more of the plurality of measurement regions and focus the received measurement light onto the surface of a diffractive or non-specular reflective component; and image measurement light diffracted or reflected from the diffractive or non- specular reflective component onto an active surface of a photodetector via a chromatically dispersive optical assembly and a mask such that: the position on the active surface of the photodetector at which measurement light is in focus depends on which measurement region of the plurality of measurement regions the measurement light was reflected from and the position within said measurement region from which the measurement light was reflected, and measurement light reflected from outside one of the plurality of measurement regions or measurement light not in focus at the point of reflection is at least partially blocked from reaching the photodetector by the mask.

2. The optical sensor of claim 1 , wherein the plurality of measurement regions are nonoverlapping in a lateral direction measured perpendicular to the optical axis of the first lens component.

3. The optical sensor of claim 1 or 2, wherein the optical sensor is configured to project measurement light into the plurality of measurement regions from a light sourcecomprising a plurality of light emitting areas, and wherein each light emitting area emits measurement light that is projected into a single measurement region.

4. The optical sensor of claim 3, wherein the optical sensor is configured to project measurement light into the plurality of measurement regions from the light source via the first lens component, and wherein the plurality of light emitting areas are located relative to the first lens component such that each light emitting area is located at a different longitudinal position measured parallel to the optical axis of the first lens component and at a different lateral position measured perpendicular to the optical axis of the first lens component.

5. The optical sensor of claim 3, wherein the optical sensor is configured to project measurement light into the plurality of measurement regions from the light source via the first lens component and a second lens component, and wherein the plurality of light emitting areas are located relative to the second lens component such that each light emitting area is located at a different longitudinal position measured parallel to the optical axis of the second lens component and at a different lateral position measured perpendicular to the optical axis of the second lens component.

6. The optical sensor of any of claims 3 to 5, wherein the light source comprises a single light emitting component and a first mask, wherein the first mask is configured to divide the light emitting component into the plurality of light emitting areas by partially blocking light emitted by the light emitting component.

7. The optical sensor of claim 6, wherein the light emitting component is an array of light emitting diodes.

8. The optical sensor of any of claims 3 to 5, wherein the light source comprises a plurality of light emitting components, wherein each light emitting area is provided by one or more of the plurality of light emitting components.

9. The optical sensor of any of claims 3 to 8, wherein the plurality of light emitting regions are slit-shaped.

10. The optical sensor of any preceding claim, wherein measurement light reflected from one or more of the plurality of measurement regions is received by the first lens component and focused onto a diffractive or non-specular reflective component by a third lens component.

11. The optical sensor of claim 10, wherein: the first lens component causes longitudinal chromatic dispersion of light passing through the lens; and / or the second lens component and third lens component cause longitudinal chromatic dispersion of light passing through each of the second and third lens components.

12. The optical sensor of claim 10 or 11 , wherein the focal length of the second lens component is different to the focal length of the third lens component.

13. The optical sensor of any of claims 10 to 12, wherein all wavelengths of measurement light reflected from a given measurement region are focused at the same distance from the third lens component on the diffractive or non-specular reflective component.

14. The optical sensor of any preceding claim, wherein the optical sensor comprises a second mask, wherein the second mask is positioned between the diffractive or non- specular reflective component and the photodetector such that focused measurement light reflected from the plurality of measurement regions is allowed to pass and measurement light reflected from outside of the plurality of measurement regions or measurement light not in focus at the point of reflection from the measurement object is at least partially blocked from reaching the photodetector.

15. The optical sensor of claim 14, wherein the second mask is located on the surface of the diffractive or non-specular reflective component.

16. The optical sensor of claim 14, wherein the second mask is located at an image plane of the diffractive or non-specular reflective component formed by a further lens component positioned in the path of measurement light between the diffractive or non- specular reflective component and the photodetector.

17. The optical sensor of any preceding claim, wherein the photodetector is oriented such that the angle between the normal to the active surface of the photodetector and the output optical axis of the chromatically dispersive optical assembly is less than 5, 10 or 25 degrees.

18. The optical sensor of any preceding claim, wherein the optical sensor is configured to receive measurement light reflected from one or more of the plurality of measurement regions through the first lens component.

19. A method for determining a three-dimensional shape of a measurement object using the optical sensor of any preceding claim, the method comprising: measuring a first set of three-dimensional coordinates from which focused measurement light is reflected from the surface of the measurement object at the intersection of the measurement object and one or more of the plurality of measurement regions; displacing the measurement object with respect to the optical sensor by a known displacement; measuring a second set of three-dimensional coordinates from which focused measurement light is reflected from the surface of the measurement object, determining the three-dimensional shape of the measurement object based on the first set of three-dimensional coordinates, the second set of three-dimensional coordinates, and the known displacement of the measurement object between the measurements of the first set of three-dimensional coordinates and the second set of three-dimensional coordinates.

20. The method of claim 19, wherein the method further comprises: displacing the measurement object with respect to the optical sensor by a second known displacement; measuring a third set of three-dimensional coordinates from which focused measurement light is reflected from the surface of the measurement object; and wherein determining the three-dimensional shape of the measurement object is further based on the third set of three-dimensional coordinates and the known second displacement.

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