Self-centering lens housing and objective for a metrology camera

Abstract

This invention relates to a self-centering lens housing and objective lens for a metrological camera. The lens housing includes a first support region for supporting a first optical element and a second support region for supporting a second optical element, spaced apart from each other. The first and second support regions are each shaped as part of the surface of at least one right cone, such that the supports for the first and second optical elements are self-centering with respect to translation in all directions and tilt about the optical axis.

Description

Technical Field

[0001] This invention relates to a lens housing and objective lens for a metrological camera with a self-centering housing having optical elements. Background Technology

[0002] In metrology, the general goal is to determine the geometric properties of one or more target objects, such as coordinates, distances, and orientations, using measuring devices. In most cases, these properties must be determined relative to a known reference system, for example, defined by one or more known reference points. Methods and systems for measuring target coordinates are used in many applications, such as highly precise measurements in geodesy, measurement problems in construction and installation, or for controlling industrial processes. Measurement and analysis instruments using machine vision or light-based technologies are widely used for quality assurance of parts and components in machines, medical devices, and semiconductor products. For example, optical metrology equipment is frequently used in industry for non-contact evaluation of workpieces or substrates during manufacturing. In optical metrology, the sample being measured is illuminated, for example, simply by ambient light or by a dedicated light source with a single or multiple wavelengths. After interacting with the sample, the generated light is collected by an objective lens and detected / imaged by an image sensor. The resulting measurement image is analyzed to determine the desired characteristics of the sample. Typically, optical metrology and inspection systems are used to measure and provide rapid feedback to improve process control in manufacturing processes, enabling real-time process control (in-situ or online measurement).

[0003] For this purpose, images can be captured by a measuring camera, for example, integrated into a measuring machine (such as a CMM, e.g., an image-based 3D measuring machine, also known as a vision measuring machine), to obtain small-scale 3D information, such as for measuring the dimensions of a workpiece for quality control purposes. Here, "small-scale" refers to the range of millimeters, micrometers, and nanometers. The images acquired by the measuring camera are precisely located in three dimensions (3D), and the features of the workpiece can also be precisely located within the image itself, provided that the camera has been properly calibrated beforehand. This calibration ensures a known relationship between the pixels of the captured image and the size of the real world, and that lens distortion is appropriately compensated for.

[0004] As understood herein, a camera includes: an objective lens; an objective lens holder having a receiving opening into which the objective lens is inserted; and an image sensor (also called a camera chip), wherein the image sensor and the objective lens are arranged relative to each other in such a way that an image can be imaged on the focused image sensor, or may be arranged relative to each other in such a way that an image can be imaged on the focused image sensor. The following can be used as a camera or camera chip: CMOS, CCD, distance imaging camera (for depth measurement over time of flight), photodiode array, focal plane array, thermal camera, and multispectral sensor. The image sensor is in conductive contact, for example using a printed circuit board (also called a circuit board or PCB), such that an electrical signal generated by incident light in the image sensor is forwarded to the printed circuit board. The electrical signal can then be processed by evaluation electronics, for example, units located on or electrically connected to the printed circuit board, or units connected by means of other signal transmission devices.

[0005] Furthermore, here, the term "objective lens" is used in the sense of one or more objectives or generally specifically as a hollow body in which an objective lens is arranged. Focusing can be achieved by repositioning the lens in the objective lens holder or by twisting or shifting the tube in which the lens is located. Depending on the requirements, one or more spectral filters or apertures may also be provided in the optical path of the camera system, i.e., for example, attached to the tube or the camera chip. The camera system can be designed to image wavelengths in the visible light range, but it can also image wavelengths in the near-infrared and far-infrared wavelength ranges.

[0006] Metrological camera systems of the type described above are typically components of relatively high-quality cameras and often feature variable focus. In a simplified implementation of such a camera system, the focusing device ensures focus. Here, the objective thread is actuated by a motor drive, allowing the distance between the image sensor and the objective to be variably set by twisting the objective in the objective holder as described above, thus enabling the production of a sharp image on the image sensor over a wide range. Generally, the requirements for calibration capability or precision, or tolerable aberrations (e.g., those that may arise from vibration or temperature variations), for camera systems used in such cameras can be well met using currently available structural and technical components. However, if this involves very precise image capture, such focusing devices often act as sources of error because their many parts can move relative to each other.

[0007] Another source of error in precision applications may lie in the different coefficients of thermal expansion within the objective lens, specifically the objective lens itself and the tube supporting the lens, but also present between the objective lens and its holder. Typically, the objective lens is made of glass, therefore, in aGl =0.5*10 -6 K -1 Up to 9*10 -6 K -1 It has a relatively small coefficient of thermal expansion α within the range Gl In contrast, the tube or objective lens holder is typically made of aluminum or an aluminum alloy, and therefore its coefficient of thermal expansion α is higher. Ob Located at a Ob =22*10 -6 K -1 Up to 24*10 -6 K -1 Within the range.

[0008] In short, objectives used in optical metrology have extremely high tolerance requirements. Therefore, the housings or bases of optical elements (especially lenses) are very demanding in terms of manufacturing and long-term stability / precision. This is especially true in applications with conditions involving high temperature variations or mechanical influences (such as shocks or vibrations), as is often the case in industrial online inspection systems or outdoor equipment used for precision metrology (such as geodesics). Metrological objectives known in the art either lack precision or require complex mounting structures and / or fine manufacturing, particularly regarding the mounting or alignment of the objective's optical elements, whose relatively small size / diameter (typically in the millimeter range) makes things even more difficult. Summary of the Invention

[0009] Therefore, the object of the present invention is to provide a lens housing and objective lens that can precisely enclose an optical element assembly.

[0010] This objective is achieved by implementing the features of the invention. Features that further develop the invention in alternative or advantageous ways are described.

[0011] The present invention relates to a lens housing for encapsulating at least a glass lens (as a first optical element) and a second optical element of a measuring camera. The lens housing includes a first support region for supporting the first optical element and a second support region for supporting the second optical element, wherein the first support region and the second support region are spaced apart from each other in the optical axis direction of the lens housing.

[0012] The closed first and second support regions are each shaped as a segment or section of the surface of at least one straight cone (cone envelope), the central axis of which is coaxial with or extends along the optical axis. Optionally, the maximum diameter is 30 mm or 14 mm (the maximum diameter refers to the diameter at the widest opening of the support region, i.e., the narrowing in the direction of the optical axis). The supports of the first and second optical elements are each self-centering with respect to translation in all directions and tilt about the optical axis.

[0013] That is, there exists a mounting assembly for mounting at least two optical elements (continuously spaced along the optical axis), one of which is a glass lens, wherein the stop for the element has an inclined, tapered contact surface with self-centering receiving characteristics. Therefore, the optical axes of the optical elements are self-aligned with each other relative to the optical axis of the lens housing. At least two centering surfaces lie on an imaginary tapered surface with an inclination angle toward the optical axis equal to half the draft angle of the tapered surface, optionally between 60° and 120° or 70° and 110°. These value ranges are advantageous for the self-centering and optional non-self-locking support of the respective optical elements. Preferably, the draft angle or inclination angle of the first support region is equal to the draft angle or inclination angle of the second support region.

[0014] As another option, the housing of the corresponding optical element is locally defined, for example, it is virtually linear (in the case that the support area is a complete closed circle as a segment of a cone envelope or multiple spaced segments of such a circle) or point-like (in the case that different support points are spaced points on a circle).

[0015] Optionally, at least the first and second support areas, or alternatively the lens housing as a whole, are made of metal, particularly anodized aluminum, glass, and / or ceramic. Alternatively, the first and second support areas are arranged in such a way that they are accessible to the lathe tool in the same clamping chamber.

[0016] The present invention also relates to an imaging objective for a metrological camera, the imaging objective preferably having a length between 5 mm and 30 mm. The objective includes at least a first lens housing and a first optical element, specifically implemented as a glass lens, and at least a second optical element (e.g., another lens, aperture, filter, or DOE). The first lens housing includes a first support region for supporting the first optical element and a second support region for supporting the second optical element, wherein the first and second support regions are spaced apart from each other in the direction of the optical axis of the objective (therefore, the lens housing serves as a lens spacer). The lens housing may be specifically implemented as at least one unit or module separate from the objective (main) body, or specifically implemented as part of the objective body.

[0017] The respective support area and / or contact area of ​​the first or second optical element for contacting the respective support area are each shaped as part of the surface of at least one straight cone, such that the supports of the first and second optical elements are self-centered with respect to translation in all directions and tilt about the optical axis, and the central axis of at least one straight cone extends along the optical axis.

[0018] This design allows the optical element to be centered in the corresponding support area, for example, by activating the lens spacer (e.g., via ultrasound). There is no need to use some positioning device to center or align it via target positioning; the optical element moves "automatically" to the centered position.

[0019] Preferably, the optical axis of the corresponding optical element is coaxially aligned with the optical axis of the objective lens solely due to the self-centering support. That is, advantageously, optimal coaxial alignment of the glass lens and other optical elements does not require any other means or procedures.

[0020] As another preferred option, the lens housing is self-centering because it has an outer support region shaped as part of another straight cone surface, wherein the central axes of the outer cone and at least one inner cone are coaxial. That is, the lens housing provides an inner support region for the optical element shaped according to one or more inner cones, and itself has an outer region shaped according to at least one outer cone for supporting the lens housing via the objective lens / tube. Therefore, not only is the optical element self-centering, but the lens housing is also self-centering. Thus, all components critical to the optical path can be perfectly aligned "automatically" with the optical axis of the objective lens or the image sensor of the camera.

[0021] In a preferred embodiment, the objective lens includes a fixing device for securing the lens housing and / or optical elements. Optionally, the fixing device is adapted in such a way that there is no play in the corresponding fixation of the lens housing or optical elements. As another option, at least one of the fixing devices is specifically implemented as a single element, i.e., only one part of each (optical) element is fixed or pressed onto a support point. Optionally, the first and second optical elements are preloaded by a force at least one hundred times the weight (gravity) of the respective optical elements, wherein preferably, the force is at most 100 N. The force can be applied from only one side or from both sides.

[0022] Optionally, the surfaces of the corresponding support and / or contact areas are coated with a hardened (e.g., anodized) and / or low-friction coating. Alternatively, the objective lens comprises a material with a different coefficient of thermal expansion, particularly with respect to the coefficient of thermal expansion of the lens housing, which differs from that of the first and / or second optical elements.

[0023] The present invention also relates to a metrological camera having an imaging objective lens comprising at least a first lens housing and a first optical element and at least a second optical element, specifically implemented as a glass lens. The first lens housing includes a first support region for supporting the first optical element and a second support region for supporting the second optical element, wherein the first and second support regions are spaced apart from each other in the optical axis direction of the objective lens. The respective support regions and / or contact regions of the first or second optical element for contacting the respective support regions are each shaped as part of the surface of at least one straight cone, such that the supports of the first and second optical elements are self-centering with respect to translation in all directions and tilt about the optical axis, the central axis of the at least one straight cone extending along the optical axis. Attached Figure Description

[0024] The lens housing and objective lens according to the invention, as well as the method according to the invention, will be described in more detail below by way of example only, with reference to exemplary embodiments schematically depicted in the accompanying drawings.

[0025] More specifically, in the attached diagram:

[0026] Figure 1 A schematic 3D view of an exemplary embodiment of a lens housing for mounting at least two optical elements, including at least one glass lens, is shown.

[0027] Figure 2 An exemplary objective lens for a metrological camera is schematically shown in a cross-sectional view, and

[0028] Figure 3a , Figure 3b A schematic cross-sectional view of a portion of the objective lens is depicted. Detailed Implementation

[0029] Figure 1 A 3D view of an exemplary embodiment of the lens housing 3 for a metrology camera is shown. Such a metrology camera is, for example, part of an industrial or geodetic system, such as a visual inspection system, a 3D scanner, a photogrammetry system, a machine vision device, a 3D microscope, or a surveying system.

[0030] In the example, the lens housing is formed as a lens barrel having a circular inlet region 7 and a circular outlet region 8 with a diameter smaller than that of the inlet region 7. The lens housing 3 includes two support regions 1 and 2 (marked in gray in the figure), namely, a first support region 1 located at the front in the example and a second support region 2 located in the middle section of the lens barrel in the example. In the example, the second support region 2 is smaller than the first support region 1; however, they may also have the same size or diameter, or the second support region may be larger than the first support region. Preferably, the maximum diameter of the support regions 1 and 2 is at most 30 mm, and particularly at most 14 mm.

[0031] Support regions 1 and 2 are each designed to support optical elements, at least one of which is a glass lens. The optical axis 5 of the lens housing is defined by the midpoints C1 and C2 of the support regions 1 and 2 (in the example, the centers of circles or rings that can be inscribed in the respective support regions 1 and 2). In the example, the optical axis 5 is the same as or coaxial with the central axis of the barrel defined by the lens barrel 3, particularly within a tolerance of 20 micrometers or 10 micrometers. The two support regions 1 and 2 are spaced apart from each other in the direction of the optical axis 5.

[0032] The corresponding support regions 1 and 2 each lie on the surface of an "imaginary" right cone 4. In the example, both regions 1 and 2 are part of the same cone 4; however, each support region 1 and 2 can be part of a separate or different cone envelope, whereby the central axis 6 of each cone is coaxial with the optical axis (the apex and center of the cone's base lie on the optical axis 5). In any case, each support region 1 and 2 narrows along the optical axis 5 in the sense that the diameter of the enclosed region decreases along the direction of the optical axis 5.

[0033] Each support region 1, 2 has a uniform tilt angle toward the optical axis 5, which is half the draft angle α of the cone 4. Preferably, the draft angle α or tilt angle of both support regions 1 and 2 is the same; however, the corresponding angles of different support regions 1 and 2 may also be different. Preferably, the draft angle is between 60° and 120°, most preferably between 70° and 110°, which means that the tilt angles are between 30° and 60° and between 35° and 55°, respectively. The most preferred tilt angle is 45°.

[0034] Such an angle of inclination is particularly advantageous for the self-centering support of the corresponding optical elements achieved through the tapered support regions 1 and 2 of the lens housing 3. The specific tapered shape of the receiving sections 1 and 2 allows for the support of locally defined or restricted optical elements (especially glass lenses). The current lens mount 3 advantageously provides self-centering stops for translation of at least two optical elements in all directions and for tilting (yaw and pitch) about the optical axis 5.

[0035] When optical elements (lenses, filters, apertures, etc.) are inserted into lens housing 3, the optical elements self-center, for example, by gravity and by vibration, particularly by ultrasound, without requiring active or external positioning or alignment as is the case in lens housings known in the art. Proper alignment of the optical elements relative to the optical axis (and relative to each other) is achieved automatically without the application of force or additional spacers. Because the supports for the respective optical elements are non-locking, they are not locked even in the event of dimensional changes (e.g., caused by temperature variations).

[0036] Lens assembly 3 can be a single piece as shown in the figure; however, it can also be an assembly of multiple modules or parts. For example, in a common frame / house / objective (tube), a first component or first lens spacer including a first stop 1 is sequentially mounted to a separate second component or second lens spacer including a second stop 2. The objective lens may further include multiple lens housings 3.

[0037] Especially in the case of the single-component lens housing 3, the geometry is chosen such that the first support region 1 and the second support region 2 are accessible to the lathe tool in the same clamping as in the example shown, and they face the same direction (forward), thus the diameter of the inner support region 2 is smaller than that of the outer support region 1. In other words, the two (all) stops are arranged in a way that allows them to be manufactured in a single manufacturing step.

[0038] However, the corresponding support regions 1 and 2 do not need to be formed as complete, closed, or continuous (narrowing) rings as shown in the figure. Instead, they can be preferably arranged axially symmetrically with respect to discrete or separate points or portions spaced apart from another distribution on a portion of the conical surface surrounding the central axis 6. In other words, the support regions 1 and 2 are not necessarily continuous 360° segments or bands of a conical envelope, but can also be multiple points or segments located on such a conical envelope or band, preferably equidistant from each other.

[0039] Preferably, the lens housing 3 is made of metal, preferably of anodized aluminum, glass, and / or ceramic. Or at least the support regions 1 and 2 are made therefrom; for example, in the case of the modular lens housing 3 as described above, the lens housing 3 can be a combination of different materials. These materials combine durability and low friction, or, from another perspective, relatively high sliding performance, which is beneficial for self-centering.

[0040] Figure 2 An exemplary objective lens 10 for a metrological camera is shown in a cross-sectional view (where the optical axis 5 is located in the image layer, i.e., a cross-section along the optical axis 5). The preferred dimensions of this imaging metrological objective lens 10 are between 5 mm and 30 mm. Therefore, the shape factor of the objective lens 10 is relatively small, because... Figure 1 or Figure 2 As shown, multiple stop components are arranged in combination within a lens housing.

[0041] In the example, objective lens 10 includes a first lens housing 3, a second lens housing 3', and a third lens housing 3'" with tapered support regions. Each lens housing 3, 3', 3" encapsulates multiple optical elements 11-12', such as lenses, filters, apertures, and diffractive optical elements (DOEs). At least one of the optical components is a glass lens; plastic lenses generally do not meet the high requirements of metrological cameras for industrial and / or geodetic surveying according to the present invention. In addition to the tapered encapsulated optical elements, the measuring objective lens 10 may include additional optical elements with conventional housings / bases.

[0042] To mount optical elements 11-12', each lens housing 3, 3' includes multiple encapsulation stops, of which only three (numbered 1, 2, 2a, within the dashed box) are indicated in the figure for better clearance. It can be seen that the first lens housing 3 and the second lens housing 3' are specifically implemented as separate components, inserted into the objective lens housing, while the third lens housing 3' supporting optical elements 12a, 12b is part of the housing or objective lens 10. That is, for example, the support region 2a supporting the optical element 12a is part of the objective lens body or directly contacts the objective lens body.

[0043] Such as about Figure 1 As described in principle, the support regions 1, 2, 2a provided by the lens housings 3, 3', 3" each narrow along the optical axis 5 according to the surface or envelope of the cone. The figure indicates two of these virtual cones 4, 4' (cone 4 for the first housing 3, cone 4' for the second housing 3'). Each cone 4, 4' is a straight cone with its central axis located on the optical axis of the objective lens 10, wherein, in the example, the cone 4 of the first lens spacer 3 is oriented relative to the cone 4' of the second lens spacer 3'.

[0044] Due to the design of the tapered support regions 1, 2, 2a, the optical axes of the individual optical elements 11, 12, 12a, 11', 12' are coaxially aligned with the optical axis 5 of the objective lens 10, solely due to the provided self-centering support. That is, the corresponding optical elements 1, 2, 2a, such as the glass lens, are self-centering in terms of displacement (translation relative to the optical axis 5) and tilt (tilt relative to the optical axis 5). Therefore, the optical elements 1, 2, 2a are automatically aligned.

[0045] In the example, objective lens 10 includes fixing devices 9 such as flexures, O-rings, or spring elements, by which the corresponding optical elements 1, 2, 2a are fixed in their self-centering positions / alignments. As shown, the fixing device 9 is therefore preferably implemented as a single (e.g., ring-shaped) element. As shown, each optical element 1, 2, 2a can be fixed by its own fixing device 9, or alternatively, the fixing device 9 can fix more than one optical element 1, 2, 2a.

[0046] As another option, the optical element / support area is fixed in a way that is not affected by the optical axis direction and / or is fully adapted to the optical element / support area so that the corresponding optical element is pressed against the support point, thereby preventing the optical element 11-12' from lifting, even in the event of geometric fluctuations or instability (e.g., due to temperature changes).

[0047] For example, the fixing device 9 preloads the corresponding optical elements 11-12' with a force at least one hundred times the weight (gravity) of the corresponding optical elements, typically in the range of 10N-20N, and therefore preferably not exceeding a maximum force of 100N. Alternatively, the preload is lower than the maximum force generated by deformation caused by temperature changes (e.g., expansion of the corresponding optical elements 11-12' and / or the corresponding lens spacers 3-3"), thereby avoiding any stress caused by different length / size variations due to different CTEs of the optical elements and lens housings / objectives.

[0048] In the example, the two separate lens housings 3, 3' are self-centeringly supported by the objective lens 10. Here, they have an outer support region (one of which is marked in the figure by a dashed closed mark with reference numeral 13), which also narrows along the optical axis 5. As shown in the figure with an exemplary "imaginary" cone 14, in addition to the inner cones 4, 4' describing the support regions 1, 2, 2a for the optical elements, there is also an outer cone 14 describing the support region 13 for supporting the lens housings 3, 3' themselves.

[0049] Like the inner cones 4 and 4', the central axis of the outer cone 14 is coaxial with the optical axis 5 of the objective lens 10. In other words, the central axes of the inner cones 4 and 4' and the outer cone 14 are the same (however, their draft angles and the positions of their apexes and lengths may differ). Therefore, Figure 2 The embodiment shown can be represented or described as a biconical shape, providing a double self-centering objective lens assembly having concentric (at least concentric within a tolerance of up to 20 μm or particularly up to 10 μm) inner and outer support regions. Such an arrangement can be further extended, for example, by stacking multiple such self-centering lens housings together.

[0050] Figure 3a , Figure 3b A cross-sectional view of a portion of the objective lens used for a measuring camera is shown (where the optical axis 5 is located in the image layer), in which only a portion of the lens housing 3 and optical element 11 are depicted.

[0051] Figure 3a The arrangement in principle described above is illustrated. The support region 1 narrows along the optical axis 5, immediately following the surface of the cone 4, whose axis 6 is the same as the optical axis 5. Therefore, a support point is provided that is inclined toward the optical axis in a plane containing the optical axis 5, with an inclination angle of half the draft angle α of the cone.

[0052] Correspondingly, the optical element 11 in the example has a rectangular edge or contact area facing the support region 1. The geometry formed between the lens housing 3 and the optical element 11, and between the contact area of ​​the support region 1 and the element, provides a locally defined, in this example, practically point-like or line-like housing 16 for the optical element 11.

[0053] According to Figure 3b In another implementation, the arrangement is reversed. In this example, the lens housing 3 shows an edge, while the contact area 15 of the optical element 11 is conical. That is, for example, the outer circular surface of the glass lens 11 is shaped according to a cone 4 parallel to the optical axis 5, and the axis 6 of the cone is again the same as the optical axis 5. Therefore, in this case, the area 15 to be supported is the conical shape of the optical element 11.

[0054] Generally, at least one side of the support area 1 or contact area 15 shows a cone (part) 4. The other side facing the cone does not need to be shaped as a cone, but can have a different geometry. For example, the side or area facing the cone side can be designed as a straight ring or three or more circumferential support points.

[0055] Therefore, in all cases, the contact area between the optical element 11 and the lens housing 3 is reduced to a finite area, or even minimized to a point that is essentially a line (circle) or a continuous point on the circumference. This small or even minimal contact area is particularly advantageous for self-centering supports.

[0056] Optionally, an intermediate medium, such as a coating, lubricant, or bearing assembly, exists between the lens housing 3 and the optical element 11, thereby adapting the medium in a manner that does not disrupt or interfere with the original tapered shape / geometry. Advantageous media include, for example, hardening the corresponding contact area and / or making the surface flatter / uniform / polished, thus supporting self-centering. It is desirable that the roughness of the contact or support surfaces, with or without coating, is as low as 1.6 μm or 0.8 μm (Ra) or better.

[0057] While the invention has been illustrated above, some preferred embodiments have been referred to in part. It should be understood that various modifications and combinations of different features of the embodiments are possible. All such modifications are within the scope of the appended claims.

Claims

1. A lens housing for encapsulating at least a glass lens and a second optical element of a measuring camera, wherein the glass lens serves as a first optical element, and the lens housing comprises: a first support region for supporting the first optical element, and a second support region for supporting the second optical element, The first support region and the second support region are spaced apart from each other along the optical axis of the lens housing. Its features are, The first support region and the second support region are each shaped as part of the surface of at least one straight cone, referred to as an inner cone, such that the supports of the first and second optical elements are each self-centering with respect to translation in all directions and tilt about the optical axis, the central axis of the straight cone being coaxial with / extending along the optical axis, wherein the supports of the respective optical elements are non-locking. The contact area between the corresponding optical element and the lens housing is actually a point-like contact or a line-like contact. The line-like contact is in the form of a complete closed circle that is a segment enclosed by the cone of the straight cone, or in the form of multiple spaced segments of the circle. The point-like contact is in the form of spaced support points on the circle. The surfaces of the corresponding support areas and / or contact areas are coated with a hardened and / or low-friction coating.

2. The lens housing according to claim 1, Its features are, The draft angle of the corresponding support area is between 60° and 120°.

3. The lens housing according to claim 2, Its features are, The draft angle of the corresponding support area is between 70° and 110°.

4. The lens housing according to any one of claims 1 to 3, Its features are, The maximum diameter of the corresponding support area is 30 mm.

5. The lens housing according to claim 4, Its features are, The maximum diameter of the corresponding support area is 14 mm.

6. The lens housing according to any one of claims 1 to 3, Its features are, The first support area and the second support area are arranged in such a way that they are accessible to the lathe tool in the same clamping.

7. An imaging objective for a metrological camera, the imaging objective comprising a first lens housing, a first optical element, and at least a second optical element, wherein the first optical element is specifically implemented as a glass lens, wherein... The lens housing includes a first support region for supporting the first optical element and a second support region for supporting the second optical element. The first support region and the second support region are spaced apart from each other along the optical axis of the objective lens. Its features are, The respective support area and / or contact area of ​​the first or second optical element for contacting the corresponding support region are each shaped as part of the surface of at least one straight cone called an inner cone, such that the supports of the first and second optical elements are self-centering with respect to translation in all directions and tilt about the optical axis, the central axis of the straight cone extending along the optical axis, wherein the supports of the respective optical elements are non-locking. The contact area between the corresponding optical element and the lens housing is actually a point-like contact or a line-like contact. The line-like contact is in the form of a complete closed circle that is a segment enclosed by the cone of the straight cone, or in the form of multiple spaced segments of the circle. The point-like contact is in the form of spaced support points on the circle. The surfaces of the corresponding support areas and / or contact areas are coated with a hardened and / or low-friction coating.

8. The objective lens according to claim 7, Its features are, Due to self-centering support, the optical axis of the corresponding optical element is coaxially aligned with the optical axis of the objective lens.

9. The objective lens according to claim 7 or 8, Its features are, Because the lens housing has an outer support region shaped as part of the surface of another straight cone called the outer cone, the lens housing is supported in a self-centering manner, wherein the central axes of the outer cone and at least one inner cone are coaxial.

10. The objective lens according to claim 7 or 8, Its features are, The objective lens includes a fixing device for fixing the lens housing and / or the optical elements, wherein, Correspondingly, there is no gap in the direction of fixation on the optical axis, and / or At least one of the fixing devices is used to fix at least two optical elements.

11. The objective lens according to claim 7 or 8, Its features are, The first optical element and the second optical element are preloaded with a force at least one hundred times the weight of the respective optical element.

12. The objective lens according to claim 11, Its features are, The first optical element and the second optical element are preloaded by a force of at least one hundred times the weight of the respective optical element via a spring element, wherein the maximum force is 100 N.

13. The objective lens according to claim 7 or 8, Its features are, The surfaces of the corresponding support areas and / or contact areas have a roughness of Ra≤1.6 µm.

14. The objective lens according to claim 13, Its features are, The surfaces of the corresponding support areas and / or contact areas have a roughness of Ra≤0.8 µm.

15. The objective lens according to claim 7 or 8, Its features are, The length of the objective lens is between 4 mm and 40 mm.

16. The objective lens according to claim 15, Its features are, The length of the objective lens is between 5 mm and 30 mm.

17. The objective lens according to claim 15, Its features are, The length of the objective lens is between 10 mm and 25 mm.

18. The objective lens according to claim 7 or 8, Its features are, The objective lens comprises materials with different coefficients of thermal expansion, wherein at least the lens housing, the first optical element, and the second optical element have different coefficients of thermal expansion.

19. A measuring camera for industrial and / or geodetic surveying, Its features The objective lens according to claim 7.

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