A novel chromatic confocal sensor with imaging capability for six-axis spatial distribution calibration

Abstract

The present invention discloses a color confocal sensor, which is configured to calibrate the orientation of a device around the optical axis of the color confocal sensor, wherein the device is arranged in a first direction around the optical axis of the color confocal sensor, and the color confocal sensor comprises: a light source, a collimator, a lens and a graticule, wherein the collimator and the lens are coaxially arranged along the optical axis, the graticule is configured to be insertable between the collimator and the lens along the optical axis, an image is configured to be projected onto the device by the light source through the collimator, the graticule and the lens, and the image is arranged in a second direction around the optical axis, and the device can be calibrated by aligning the device with the image so that the first direction is close to the second direction.

Description

Technical Field

[0001] The present invention relates to a chromatic confocal sensor with imaging capability for six-axis spatial distribution calibration practice. In particular, the present invention relates to a chromatic confocal sensor with imaging capability for configuring an integrated optical metrology device for multiple optical functional modules seeking geometric relationships. Background Art

[0002] In one application, a chromatic confocal sensor can be used to measure depth or distance in the Z direction in any application, where the Z direction is the direction of the sensor's optical path. The output of the chromatic confocal sensor can be used to generate a position measurement value of a device based on the Z direction measurement. For example, the chromatic confocal sensor can be arranged at various XY positions in the XY coordinate plane to obtain Z direction data, thereby expanding the position data used to fill the device, the position of which is measured as a distance from the XY plane to generate position data expressed in the (X, Y, Z) coordinate system, or a direction expressed as an angle rotated around the X axis, the Y axis, and the Z axis, respectively. However, conventional chromatic confocal sensors can only generate a three-dimensional position, which can be specified by an (X, Y, Z) coordinate system and a direction (or (RX, RY, RZ), where RX represents an angle around the X axis or tilt, RY represents an angle around the Y axis or tilt, and RZ represents an angle around the Z axis or rotation). If the feature of the device to be detected is symmetric around the Z axis, that is, an axis coaxial with the optical axis of the chromatic confocal sensor, then the three-dimensional position is specified as a rotation value around only two of the three axes of the base coordinates. Thus, in a conventional chromatic confocal sensor used in conjunction with, for example, a device having an entrance pupil coaxially aligned with the conventional chromatic confocal sensor, no RZ or rotational data is available because features of the entrance pupil or other features surrounding the entrance are symmetric about the optical axis of the sensor.

[0003] What is needed is a chromatic confocal sensor that can provide indications of all rotation angles about all X, Y, and Z axes. Summary of the invention

[0004] OBJECT OF THE INVENTION: One object of the present invention is to provide a tool capable of providing an indicator so that the orientation of a device around the optical axis of the tool can be obtained or indicated; another object of the present invention is to provide a chromatic confocal sensor capable of providing an indicator so that the orientation of a device around the optical axis of the tool can be obtained or indicated; another object of the present invention is to provide a tool capable of providing position data and rotation data, including indications of rotation angles about all X, Y and Z axes.

[0005] Technical solution: The color confocal sensor described in the present invention is configured to calibrate the direction of a device around the optical axis of the color confocal sensor, wherein the device is arranged in a first direction around the optical axis of the color confocal sensor, and the color confocal sensor includes: a light source; a collimator; a lens; and a graticule, wherein the light source, the collimator and the lens are coaxially arranged along the optical axis, the graticule is configured to be insertable between the collimator and the lens along the optical axis, the image is configured to be projected onto the device by the light source through the collimator, the graticule and the lens, the image is arranged in a second direction around the optical axis, and the device can be calibrated by aligning the device with the image so that the first direction is close to the second direction.

[0006] In one embodiment, the reticle is configured to be removable from the optical axis.

[0007] In one embodiment, the reticle is configured to be removable from the optical axis and the reticle is configured to be arranged on a wheel, wherein a first rotation of the wheel arranges the reticle along the optical axis and a second rotation of the wheel arranges the reticle away from the optical axis.

[0008] In one embodiment, the reticle is a pair of orthogonally arranged crosshairs.

[0009] In one embodiment, the reticle is a pair of orthogonally arranged opaque crosshairs on a transparent background.

[0010] In one embodiment, the reticle is a pair of orthogonally arranged transparent crosshairs on an opaque background.

[0011] In one embodiment, the reticle is a pair of orthogonally arranged crosshairs of different lengths.

[0012] In one embodiment, the device is an optical imaging system having external aperture and / or rotational alignment requirements.

[0013] In one embodiment, the chromatic confocal sensor further comprises a wheel, and the graticule is configured to be arranged on the wheel, the wheel being configured to be rotatable about a rotation axis, wherein the rotation axis is substantially parallel to the optical axis, a first rotation of the wheel arranges the graticule along the optical axis, and a second rotation of the wheel arranges the graticule away from the optical axis.

[0014] Advantageous effect: The color confocal sensor of the present invention includes an additional part, such as a graticule, which can be used as an indicator when an image is projected onto a part of the device through the additional part, so that the device will be calibrated in the direction around the optical axis of the color confocal sensor of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a schematic diagram depicting a chromatic confocal sensor for providing displacement and distance measurements and their derivatives;

[0016] Figure 2 is a schematic diagram depicting a chromatic confocal sensor which is used only to provide the three-dimensional coordinates of a device under test and the rotation angles around the X-axis and the Y-axis;

[0017] Figure 3 is a schematic diagram depicting a chromatic confocal sensor of the present invention for providing three-dimensional coordinates and all rotation angles about the X, Y and Z axes of a device being measured;

[0018] Figure 4 is a diagram depicting one type of reticle and its effectiveness as a target direction indicator;

[0019] Figure 5 is a diagram depicting one type of reticle and its effectiveness as a target direction indicator;

[0020] Figure 6 is a diagram depicting another type of reticle and its effectiveness as a target direction indicator;

[0021] Among them, chromatic confocal sensor 2; light source 4; collimator 6; graticule 8; objective lens 10; optical axis 12; first direction 14; second direction 16; projected image 18; device 20; spectrometer 22; wheel 24; graticule 26; opening 28; external aperture 30; crosshairs 32; crosshairs 34; collimated or conjugate image plane 36; emission port 38; central axis 40; lens 42. DETAILED DESCRIPTION

[0022] The term "approximately" as used herein means approximately, roughly, about, or within the range of. When the term "approximately" is used in conjunction with a numerical range, it modifies the numerical range by extending the upper and lower boundaries of the set numerical values. Generally, the term "approximately" as used herein modifies the stated value with a variance of 20% above or below the stated value.

[0023] Figure 1 is a schematic diagram depicting a chromatic confocal sensor for providing displacement and distance measurements and their derivatives. A chromatic confocal sensor uses imaging errors, i.e., chromatic aberrations of glass lenses, to measure optical distances. A beam of white light is emitted from a source through a special lens arrangement, e.g. Figure 1 The arrangement shown. Depending on the frequency, such as λ1, λ2 and λ3, etc., the light source 4 is not focused on the rainbow color line on the lens axis. When the light is reflected from the object, the color of the reflected light can be attributed to the distance between the object and the sensor. The reflected light is transmitted back to the spectrometer 22 along the same path for analysis. The relationship between the color and distance between the measured object and the lens 10 is configured in the controller of each sensor. This distance corresponds to a distance value.

[0024] Figure 2 is a schematic diagram describing a chromatic confocal sensor that is used only to provide the three-dimensional coordinates of the device 20 being measured and the angles of rotation about the x-axis and y-axis. Here, the chromatic confocal sensor 2 is used to obtain distance measurements of the surface of the device 20. It should be noted that for different parts of the device 20, such as T1 and t2, Z values ​​can be obtained, as shown by the distance of the points T1 and T2 in the z-direction relative to their spacing in the x-direction. Since the device 20 is symmetrical about its central axis 40 in its construction, the chromatic confocal sensor 2 cannot determine the orientation of the device about the central axis 40 or the angle of rotation relative to the z-axis.

[0025] Figure 3 is a schematic diagram depicting a color confocal sensor of the present invention, which is used to provide three-dimensional coordinates and all rotation angles about the X, Y and Z axes of a measured device 20. In one example, the device 20 is an optical imaging system with an external aperture 30 (e.g., an entrance pupil). In another example, the device is an optical imaging system with a rotational alignment requirement. The present invention discloses a color confocal sensor 2, which is configured to calibrate the direction of a device around an optical axis 12 of the color confocal sensor, wherein the device 20 is arranged in a first direction 14 around the optical axis of the color confocal sensor. The color confocal sensor includes a light source 4, a collimator 6, a lens 10 and a graticule 8. The collimator 6 is used to ensure that the light source 4 is converted into a parallel light beam. The graticule 8 is configured to be insertable between the collimator 6 and the lens 10 along the optical axis 12. The light source 4, the collimator 6 and the lens 10 are coaxially arranged along the optical axis 12. In use, an image 18 is configured to be projected by a light source 4 through a collimator 6, a reticle 8 and a lens 10 on a device 20, the image 18 being arranged in a second direction 16 about an optical axis, and the device 20 can be calibrated by aligning the device with the image. Here, when aligning the device 20 relative to a reticle (e.g., a portion of the outer aperture 30) projected on an image plane 36, the direction of the device 20, i.e., the first direction 14, can be adjusted so that the device 20 is ultimately oriented in a desired direction, e.g., when it approaches the second direction 16.

[0026] It should be noted that in order to detect the image, the image 18 of the reticle 8 needs to be successfully projected onto a surface. Here, the optics that handle the propagation of light beyond the color confocal sensor are now important for projecting the image 18 into an image that can be detected by an instrument, such as the same spectrometer 22 used to detect reflected light and aberrated light passing through the color confocal sensor. Here, the optics may include a lens or collimator 42 that collimates the incident light incident on the lens 42. In use, a similar image can be obtained by the spectrometer 22. Figure 3image at the bottom right. The figure shows a grid representing a grid superimposed on the projected image 18. Here, any of the vertical lines can be considered as lines representing the first direction 14, and the projected image 18 represents the target direction to which the orientation of the device 20 is to be adjusted. Here, the crosshairs of the reticle can be considered as this target direction. The reticle 8 is preferably used only when orientation about the optical axis or Z-axis of the device is required, because the reticle 8 or crosshairs will block some light and negatively affect the detection and resolution of distance measurements using the chromatic confocal sensor outside of its use to detect the orientation of the device 20 relative to the optical axis 12. If the accuracy of the distance measurement obtained by the chromatic confocal sensor is not critical or necessary, the reticle 8 can be left between the collimator 6 and the lens 10. However, in order to make the chromatic confocal sensor easy to use for all purposes for which it is configured, the reticle 8 can be made removable when it is no longer required. Figure 3 The lower left figure of depicts two reticles 8, 26 and an opening 28, all of which are disposed on the wheel 24, wherein the three features 8, 26, 28 are disposed about the axis of rotation and all of which are disposed equidistant from the axis of rotation. The reticle 8 is essentially made of two orthogonally arranged opaque crosshairs disposed on a transparent backing material such as glass, or simply made of two orthogonally arranged opaque crosshairs without a supporting backing, or the background is empty. The reticle 26 is made of two transparent orthogonally arranged crosshairs disposed on a transparent backing material, such as glass or a simple opaque plate, which includes a crosshair-shaped gap that allows light to be transmitted. In the embodiment shown, by arranging the reticles 8, 26 on the wheel 24, the reticle 18 is configured to be removable from the optical axis. In this embodiment, the reticles 8, 26 are configured to be removable from the optical axis when it is not desired or necessary to arrange the reticles along the optical axis, for example, when other measurements are made to allow the maximum amount of light to pass through the lens 10. Wheel 24 is configured to rotate about an axis substantially parallel to optical axis 12 so that the reticle is arranged orthogonally relative to the parallel beams of light produced by the light source and collimator. When selecting a reticle 8, 26 for calibrating device 20 about the direction of optical axis 12 or the Z-axis, wheel 24 is simply rotated until the desired feature is optically inserted between collimator 6 and lens 10 along optical axis 12. When the reticle is no longer needed, wheel 24 is rotated again to move the reticle away from that position. Opening 28 is provided to allow unobstructed light to pass through wheel 24 when reticle 8, 26 is no longer needed.

[0027] Newton's imaging formula. Figure 4 , Figure 5 and Figure 6 is a diagram depicting various types of reticles and their effectiveness as target direction indicators. Figure 4, the graticule 8 is shown on the left, and the sample return light signal for such graticule 8 passing through line AA is provided on the right. The light transmission area corresponds to the horizontal portion of the light level detection diagram. Here, the "signal" is essentially the tilt in the diagram where the light transmission is blocked by a portion of the vertically arranged crosshairs. Figure 5 , the graticule 26 is shown on the left, and the sample return light signal for such graticule 26 passing through line BB is provided on the right. The area where light transmission does not occur corresponds to the horizontal portion of the light level detection diagram. Here, the "signal" is essentially the "spike" in the diagram where light is transmitted through the vertically arranged hollow crosshairs. It should be noted that the latter has a higher signal-to-noise ratio compared to the other, so if the opaque background itself does not hinder adjustment efforts, Figure 5 The reticle shown in the figure provides a clearer indicator as a guide for adjusting the device orientation. Figure 6 A reticle having orthogonally arranged crosshairs of different lengths is disclosed. It should be noted that the vertically arranged crosshairs 32 are longer than the water cloth arranged crosshairs 34. Since the two have different lengths, there will be no confusion as to which crosshair represents a previously established direction, such as vertical or horizontal, which can further help the user distinguish the direction of the reticle itself when used as a target for adjusting the device's direction.

Claims

1. A chromatic confocal sensor, configured to calibrate the orientation of a device around an optical axis of the chromatic confocal sensor, characterized in that: The device is arranged in a first direction around the optical axis of the color confocal sensor, the color confocal sensor comprising: a light source; a collimator; a lens; and a graticule, wherein the light source, the collimator and the lens are coaxially arranged along the optical axis, the graticule is configured to be insertable between the collimator and the lens along the optical axis, an image is configured to be projected onto the device by the light source through the collimator, the graticule and the lens, the image is arranged in a second direction around the optical axis, and the device can be calibrated by aligning the device with the image so that the first direction is close to the second direction.

2. The color confocal sensor according to claim 1, characterized in that: The reticle is configured to be removable from the optical axis.

3. The color confocal sensor according to claim 1, characterized in that: The reticle is configured to be removable from the optical axis, and the reticle is configured to be disposed on a wheel, wherein a first rotation of the wheel positions the reticle along the optical axis and a second rotation of the wheel positions the reticle away from the optical axis.

4. The color confocal sensor according to claim 1, characterized in that: The reticle is a pair of crosshairs arranged orthogonally.

5. The color confocal sensor according to claim 1, characterized in that: The reticle is a pair of orthogonally arranged opaque crosshairs on a transparent background.

6. The color confocal sensor according to claim 1, characterized in that: The reticle is a pair of orthogonally arranged transparent crosshairs on a transparent background.

7. The color confocal sensor according to claim 1, characterized in that: The reticle is a pair of orthogonally arranged crosshairs of different lengths.

8. The color confocal sensor according to claim 1, characterized in that: The device is a device selected from the group consisting of an optical imaging system with an external aperture, an optical imaging system with rotational alignment requirements, and combinations thereof.

9. The color confocal sensor according to claim 1, characterized in that: A wheel is also included, and the graticule is configured to be arranged on the wheel, the wheel is configured to be rotatable about a rotation axis, wherein the rotation axis is substantially parallel to the optical axis, and a first rotation of the wheel sets the graticule along the optical axis, and a second rotation of the wheel sets the graticule away from the optical axis.

10. A chromatic confocal sensor configured for calibrating the orientation of a device around an optical axis of the chromatic confocal sensor, characterized in that: The device is arranged in a first direction around the optical axis of the color confocal sensor, the color confocal sensor comprising: a light source; a collimator; a lens; and a graticule comprising a pair of orthogonally arranged crosshairs, wherein the light source, the collimator and the lens are coaxially arranged along the optical axis, the graticule is configured to be insertable between the collimator and the lens along the optical axis, an image is configured to be projected onto the device by the light source through the collimator, the graticule and the lens, the image is arranged in a second direction around the optical axis, and the device can be calibrated by aligning the device with the image so that the first direction is close to the second direction.

11. The color confocal sensor according to claim 10, characterized in that: The reticle is configured to be removable from the optical axis.

12. The color confocal sensor according to claim 10, characterized in that: The reticle is configured to be removable from the optical axis, and the reticle is configured to be disposed on a wheel, wherein a first rotation of the wheel positions the reticle along the optical axis and a second rotation of the wheel positions the reticle away from the optical axis.

13. The color confocal sensor according to claim 10, characterized in that: The reticle is a pair of orthogonally arranged opaque crosshairs on a transparent background.

14. The color confocal sensor according to claim 10, characterized in that: The reticle is a pair of orthogonally arranged transparent crosshairs on a transparent background.

15. The color confocal sensor according to claim 10, characterized in that: The reticle is a pair of orthogonally arranged crosshairs of different lengths.

16. The color confocal sensor according to claim 10, characterized in that: The device is a device selected from the group consisting of an optical imaging system with an external aperture, an optical imaging system with rotational alignment requirements, and combinations thereof.

17. The color confocal sensor according to claim 10, characterized in that: A wheel is also included, and the graticule is arranged to be set on the wheel, the wheel is configured to be rotatable about a rotation axis, wherein the rotation axis is substantially parallel to the optical axis, and a first rotation of the wheel sets the graticule along the optical axis, and a second rotation of the wheel sets the graticule away from the optical axis.

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