Automatic control of single-crystal fiber growth process

Abstract

A method for growing a straight / non-tapered or tapered high-transmittance single-crystal fiber (SCF) using a fiber growth machine includes receiving an image dataset from a camera via an electronic control unit (ECU). The image data includes a feed fiber, a seed fiber, and a first group of pixels of the molten zone formed between the feed fiber and the seed fiber using a laser beam. It also includes identifying features of interest in the feed fiber, seed fiber, and / or molten zone within the first group of pixels and localizing the position-identifying pixels within the features of interest as a second group of pixels. The horizontal position of the feed fiber is controlled using the second group of pixels via the ECU during fiber growth, and includes transmitting electronic control signals to the machine's actuators. An automated system for growing the SCF includes a camera and an ECU configured to carry out this method.

Description

[Technical Field]

[0001] Introduction This disclosure relates to an automated system and method for growing high-transmittance optical fibers, such as corundum like sapphire or ruby, or other heat-resistant monocrystalline or single-crystal fibers (SCFs) suitable for use as optical propagation media. [Background technology]

[0002] Laser beams are used in countless scientific and medical applications that require a coherent beam of high-energy, monochromatic light. For example, optical-quality lasers are frequently used for precision measurements and various ophthalmic surgeries. Such applications often require compact packaging and high light transmission levels, along with low signal loss and a high signal-to-noise ratio. These and other requirements make this optical fiber an ideal solution because the intended optical fiber has a relatively short length of about 0.05 to 2 meters and a small diameter of less than about 500 microns.

[0003] High-transmittance optical quality fibers can be grown in a laboratory setting. Such fibers, hereafter referred to as SCFs for simplification and consistency of illustration, can be fabricated by a laser-heated pedestal growth (LHPG) process with the assistance of a fiber growth machine. During a typical LHPG-based process, concentrated thermal energy from a directed laser beam is used to melt the tip of a crystal or ceramic feed rod. In this way, a molten zone is formed on the plane of a position-controllable pedestal. The source crystal or seed fiber is then immersed in the molten zone and slowly withdrawn under controlled tension. Laser-based melting of the feed rod is continued simultaneously with the growth of the SCF to maintain the size of the molten zone. The resulting SCF, when grown under optimal conditions, will possess a variety of beneficial optical and structural qualities. However, slight positional variations or micro-movements of the feed rod can make achieving such optimal conditions difficult. [Overview of the project] [Means for solving the problem]

[0004] Disclosed herein is a computer-controlled system and associated method for monitoring and controlling the growth of high-transmittance single-crystal fibers (SCFs). The solution described herein automates the entire fiber growth process using machine vision capabilities and associated image processing techniques, reducing undesirable micro-motions of the SCFs during growth and minimizing internal strain, thereby making the laser-heated pedestal growth (LHPG) method outlined above more self-contained. The consistency and precision enabled by this method also result in SCFs with higher transmittance without the need for manual operator control input.

[0005] One aspect of the present disclosure includes a method for monitoring and controlling the growth of high-transmittance SCF using a fiber growth machine. One embodiment of the method includes receiving digital image data from one or more cameras via an electronic control unit (ECU). The digital image data includes a first group of pixels of seed fibers, feed fibers, and a melting zone, the melting zone being formed between the seed fibers and the feed fibers using a laser beam. The method also includes identifying features of interest of the feed fibers, seed fibers, and / or the melting zone within the first group of pixels. The ECU performs this additional action.

[0006] Subsequently, one or more position-identifying pixels within the feature of interest are identified as a second group of pixels via the ECU. The method in this embodiment then includes controlling the horizontal position of the feed fiber using the second group of pixels via the ECU during SCF growth, which includes transmitting electronic control signals to one or more actuators of the fiber growth machine.

[0007] This specification also discloses an automated system for growing high-transmittance SCF. The automated system may include at least one camera and an ECU outlined above. The camera is configured to output a digital image dataset including a first set of pixels of feed fibers, seed fibers, and molten zones. The ECU communicating with the camera includes a processor and a computer-readable storage medium on which an instruction set is recorded. The instruction set is, by extension, executable by the processor, causing the ECU to identify features of interest in the feed fibers, seed fibers, and / or molten zones within the first set of pixels, and then to locate one or more location-identifying pixels within the features of interest as a second set of pixels. The ECU then controls the horizontal position of the feed fibers during fiber growth using the second set of pixels, which includes transmitting electronic control signals to one or more actuators of a fiber growth machine.

[0008] A method in one or more embodiments may include identifying features of interest within a first pixel group by identifying saturated pixel clusters within the first pixel group. A saturated pixel cluster has a threshold brightness level indicating the location of a melt zone within the first pixel group. The method may further include locating one or more location-identifying pixels by identifying the central pixel of a saturated pixel cluster as a reference point, and then controlling the horizontal position of a feed fiber in response to positional variations of the reference point.

[0009] This method may also include maintaining the size and / or shape of the molten zone by an electronic position control signal via the ECU, so that the reference point remains stationary.

[0010] Any aspect of the present disclosure includes using an ECU to control the supply rate of a laser beam and / or feed fiber, thereby changing the size and shape of the melting zone and creating a tapered profile of the fiber.

[0011] Methods according to one or more embodiments include identifying features of interest by identifying the respective edges of the feed fiber and seed fiber within a first pixel group, and localizing the position-identifying pixels, which includes using each edge to identify a common longitudinal centerline between the feed fiber and seed fiber, and controlling the horizontal position of the feed fiber in accordance with the positional variation of the common longitudinal centerline. Identifying the respective edges of the feed fiber and seed fiber may optionally include using the Canny edge detection algorithm or an edge detection process suitable for other applications.

[0012] Receiving a set of image data from at least one digital camera may involve using a first camera to image the first optical axis of the feed fiber and a second camera to image the second optical axis of the feed fiber. In this non-limiting implementation, the first and second optical axes of the feed fiber are perpendicular to each other.

[0013] Another aspect of the present disclosure involves receiving a trigger signal from an external device via an ECU. The trigger signal indicates a request to start a fiber growth process using a fiber growth machine. In such embodiments, the method may include, in response to the trigger signal, requesting via the ECU that a digital camera begin acquiring image data.

[0014] A fiber growth machine may include a translationable platform having multiple actuators that can operate collectively to move the translationable platform with two horizontal translational degrees of freedom. Controlling the horizontal position of the feed fiber may, in turn, include controlling the actuators by electronic position control signals.

[0015] At least one camera may optionally include a first camera and a mirror. The first camera may be positioned on a first optical axis and operable to collect a portion of the image data on the first optical axis. The mirror may be positioned on a second optical axis perpendicular to the first optical axis. In this embodiment, the first camera is configured to collect another portion of the image data reflected from the mirror.

[0016] Also disclosed herein is an automated system for monitoring and controlling the growth of SCFs. One embodiment of the automated system includes a camera and an ECU. The camera outputs image data including a first group of pixels of the feed fiber, seed fiber, and molten zone. The molten zone is formed between the feed fiber and seed fiber using a laser beam in a fiber growth machine. The ECU communicates with the camera and includes a processor and a computer-readable storage medium on which an instruction set is recorded. The instruction set is executable by the processor and causes the ECU to carry out the method outlined above.

[0017] The above features and advantages of the present disclosure, as well as other possible features and advantages, should become readily apparent upon reading the following detailed description of several embodiments for implementing the present disclosure in conjunction with the accompanying drawings.

Brief Description of the Drawings

[0018] [Figure 1] FIG. 1 shows an exemplary embodiment of an automated system for monitoring and controlling the growth of a single crystal fiber (SCF) described herein. [Figure 2] FIG. 2 is a schematic diagram of a representative melt zone during the growth of an SCF. [Figure 3] FIG. 3 is a flowchart illustrating one embodiment of a method for monitoring and controlling the growth of the SCF of FIG. 2 using the automated system shown in FIG. 1.

Modes for Carrying Out the Invention

[0019] The solutions of the present disclosure may be subject to modification or presented in alternative forms. Representative embodiments of the present disclosure are shown in the drawings by way of example and will be described in further detail below. However, the inventive aspects of the present disclosure are not limited to the disclosed embodiments. Rather, the present disclosure is intended to encompass alternative forms within the scope of the present disclosure as defined by the appended claims.

[0020] Embodiments of the present disclosure are described herein. However, it should be understood that the disclosed embodiments are merely exemplary and that other embodiments may take various alternative forms. The drawings are not necessarily to scale. Some features may be exaggerated or minimized to show details of particular components. Therefore, the specific structural and functional details disclosed herein should not be construed in a limiting sense, but rather should be construed as a representative basis for teaching those skilled in the art to employ the present disclosure in various ways.

[0021] As those skilled in the art will understand, various features illustrated and described with reference to any one of the figures can be combined with features shown in one or more other figures to create embodiments not explicitly illustrated or described. The illustrated combinations of features provide representative embodiments for typical applications. However, various combinations and modifications of features consistent with the teachings of this disclosure may be desired for specific applications or implementations.

[0022] In the following explanation, certain terms may be used for reference purposes only and are therefore not intended to be limiting. For example, terms such as “up” and “down” refer to directions within the referenced drawings. Terms such as “front,” “rear,” “forward,” “backward,” “left,” “right,” “rear,” and “side” describe the orientation and / or position of a component or element within an arbitrary reference frame, which will become clear by referring to the text and related drawings describing the component or element being discussed. Furthermore, terms such as “first,” “second,” and “third” may be used to describe separate components. Such terms may include the terms specifically mentioned above, their derivatives, and terms with similar meanings.

[0023] Referring to the drawings, similar reference numerals refer to similar components, and starting with Figure 1, the automation system 10 according to this disclosure includes an electronic control unit (ECU) 12 and an imaging system 14. The imaging system 14, in the non-limiting configuration of Figure 1, includes at least one digital camera 15, for example, a first camera 15A and a second camera 15B, respectively. Each digital camera 15 is, for example, a charge-coupled device (CCD), complementary metal-oxide-semiconductor (CMOS), electron-multiplier CCD (EMCCD), or image data (CC). IMG ) can be embodied as an image sensor suitable for other applications, configured to output to the ECU12.

[0024] The automated system 10 described in detail herein is configured to monitor and control the fiber growth process of single-crystal fibers (SCFs) 16, for example, sapphire or other single-crystal materials suitable for other applications. Fiber growth as contemplated herein is carried out by a laser-heated pedestal growth (LHPG) process of the type outlined above. As understood in the art, such a process is carried out by using a laser beam (LL) from a laser device 20 to melt the tip of a feed fiber 18. The molten material of the fiber 18 then accumulates on the pedestal 22 as a molten zone (MZ) 23. The SCF 16 is then carefully withdrawn from the molten zone 23 in a controlled manner in the direction of arrow GG. The resulting SCF 16, if properly formed, can then be incorporated into a wide range of devices for applications such as spectroscopy, microscopy, ophthalmic or other laser surgery.

[0025] The automation system 10 of this disclosure may operate in conjunction with or be integrated with a fiber growth machine 25 to help optimize the entire fiber growth process when manufacturing SCF 16. As those skilled in the art will understand, an LHPG-capable fiber growth machine, such as the fiber growth machine 25 shown in a simplified form in Figure 1 (with the sealed growth chamber omitted), typically includes a table or other horizontal workbench 11 and a laser device 20, e.g., one or more laser types such as a CO2 laser diode, Er:YAG, or another laser type suitable for the application. The fiber growth machine 25 also includes a vertically translatable pedestal 22 on which the SCF 16 is grown in the direction of arrow GG, and a horizontally translatable platform device 26 operably connected to the pedestal 22.

[0026] The platform device 26 further includes a plurality of actuators 28 that provide positioning functions for the pedestal 22 with two horizontal translational degrees of freedom, while another actuator 29 translates the pedestal 22 vertically in the direction of arrow GG. The first camera 15A and the second camera 15B in this exemplary configuration can be securely mounted on the towers 30A and 30B of the telescopic tower assemblies 300A and 300B, respectively. In this configuration, the first optical axis A1 of each first camera 15A and the second optical axis A2 of the second camera 15B are arranged orthogonally to each other to image the SCF 16, feed fiber 18, seed fiber 19, and melting zone 23, which are described below. Instead of using two digital cameras 15, another portion of the image data (CC) is used. IMG One or more mirrors 34 can be placed on the second optical axis A2 to direct the ) towards the remaining digital camera 15, for example, the first camera 15A.

[0027] The platform apparatus 26, shown in the non-limiting structure of Figure 1, is coupled to a pedestal 22, which is a linear and / or rotary actuating device such as an electric motor, belt, ball screw assembly, etc. Actuators 28 can also be collectively operated to translate the platform 22. During the operation of the fiber growth machine 25, even slight positional fluctuations of the pedestal 22 and platform apparatus 28 can lead to undesirable "wobble" or other micro-motions of the feed fiber 18. Since such micro-motions can affect the transmission quality of the SCF 16, this solution aims to minimize such fluctuations. Therefore, the reduction of associated strain, notified in real time by machine vision-based feedback from a camera system 15 as described below, and the overall improvement in transmission efficiency achieved by the ECU 12 in Figure 1, aim to improve the overall level of technology regarding LHPG-based SCF growth.

[0028] As part of the intended monitoring and control strategy, the ECU 12 ultimately controls the horizontal position of the feed fiber 18. This controls the position of the actuators 28 and 29 mentioned above using an electronic position control signal (CC). P This is done by controlling it using (CC). Image data (CC) as intended herein. IMG The image data (CC) includes the feed fiber 18, the seed fiber 19, and the pixels (P1) of the first pixel group of the melting zone 23. Subsequently, the ECU 12 receives the image data (CC) IMG The ECU 12 processes the set and identifies a characteristic second pixel group (P2) from the first pixel group (P1) as described below. The ECU 12 then uses the second pixel group (P2) in a specific manner to control the operation of the fiber growth machine 25.

[0029] For this purpose, the ECU 12 communicates with the digital camera 15, for example, via a wired or wireless network or individual transmission conductors. The ECU 12 includes a processor (P) 31 and a computer-readable storage medium or memory (M) 33 on which an instruction set 35 is recorded. The instruction set 35 is executable by the processor 31 and sends image data (CC) to the ECU 12. IMG The ECU processes the position identification pixels (CC) of the feed fiber 18, seed fiber 19, and / or melting zone 23 within the first pixel group (P1) to identify features of interest. The ECU then positions one or more position identification pixels within the identified features of interest, and these position identification pixels form the second pixel group (P2). The ECU then controls the horizontal position of the feed fiber 18 using the second pixel group (P2) while the fiber growth machine 25 grows the SCF 18, which involves sending a position control signal (CC) to one or more of the actuators 28, 29 of the fiber growth machine 25. P This includes sending )

[0030] The ECU 12 schematically shown in FIG. 1 is programmed by software and can be equipped with hardware, that is, configured to implement method 100 (see FIG. 3) by using a processor 31 to execute an instruction set 35 as computer-readable instructions from its resident memory 33. An external device 27 such as a button, a dial, a keyboard, a keypad, or another appropriately constructed human-machine interface can be manually operated to generate a trigger signal (CC T ), or the trigger signal (CC T ) can also be generated autonomously. The trigger signal (CCT) may further indicate the start by user requirements or autonomous requirements for monitoring and automation using the automation system 10.

[0031] The memory 33 may include a tangible non-transitory memory, such as an optical, magnetic, flash, or other type of read-only memory, along with a sufficient amount of random access memory, electrically erasable programmable read-only memory, etc. for the application. The processor 31, on the other hand, can be constructed from various combinations such as an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), an electronic circuit, a central processing unit, a microprocessor, etc. The non-transitory components of the memory can store computer-readable instructions for controlling the operation of the fiber growth machine 25 and the automation system 10 described herein.

[0032] Referring to Figure 2, the molten zone 23 is shown in a simplified schematic manner and has an outer periphery 42. As will be understood by those skilled in the art, the size of a typical molten zone 23 is very small, for example, less than 200 microns (μ) near the seed fiber 19 and about 600 μm near the feed fiber 18. During its growth, the SCF 16 may exhibit small motions in the form of oscillating motions, and changes in the position and orientation of the SCF 16 are indicated by the outer periphery 142. That is, the common longitudinal centerline (CL) of the SCF 16 and the feed fiber 18 may deviate slightly from the true normal, as indicated by the inclination angle (θ), and thus give the SCF 16 undesirable internal strain as described above.

[0033] To identify features of interest, the ECU 12 may optionally identify saturated pixel clusters within a first pixel group (P1). As is understood in the art, SCFs tend to melt at very high temperatures, sometimes exceeding 2000°C. As a result, image pixels corresponding to the melted zone 23 tend to appear brighter than the surrounding pixels. Therefore, the ECU 12 can process the locations of detected saturated pixel clusters as corresponding to the melted zone 23.

[0034] For example, the ECU 12 shown in Figure 1 can be programmed with a threshold brightness level that is characteristic of or indicates to be a melting zone 23. The ECU 12 can then perform a digital comparison on the constituent image pixels or their clusters to determine whether they have a brightness equal to or greater than the threshold brightness level. Once the saturated pixel clusters are located, the ECU 12 can then locate any location-identified pixels as the second group of pixels (P2) described above.

[0035] One method for position-identifying pixels as a second group of pixels (P2) is to locate the central pixel (P) within the saturated pixel cluster corresponding to the melting zone 23. X This includes identifying the central pixel (P X ) is the zero point or reference position (P REF) can be registered in memory as. In such embodiments, the horizontal position of the feed fiber 18 is controlled via the ECU 12 to the reference position (P) within the saturated pixel cluster. REF This can be done in response to the position change of ( ). Subsequently, the ECU12 controls the electronic position control signal (CC) shown in Figure 1. P ) by which the reference position (P REF The size and / or shape of the molten zone 23 can be maintained so that the ) remains stationary.

[0036] In alternative or, in some cases, parallel methods, the ECU 12 may identify features of interest by identifying edges E1 and E2 of the feed fiber 18 and edges e1 and e2 of the seed fiber 19, respectively, within the first pixel group. In such an implementation, the ECU 12 can locate the location-identified pixels using the respective edges E1, E2, e1, and e2. Such action identifies the common longitudinal centerline (CL) between the feed fiber 18 and the seed fiber 19. In this case, the ECU 12 can stabilize the horizontal position of the feed fiber 18 in response to positional variations of the common longitudinal centerline (CL).

[0037] When formed according to any aspect of this disclosure, the SCF16 may have a non-tapered cross-sectional shape. However, this teaching can also be used to form an SCF16 having a tapered surface profile, for example, a truncated hourglass shape. This effect can be achieved by changing the size and shape of the melting zone 23 in real time by controlling the supply rate of the laser device 20 and / or the feed fiber 18.

[0038] Referring now to Figure 3, a method 50 for monitoring and controlling the growth of high-transmittance SCF 16 using the fiber growth machine 25 of Figure 1 is shown. Method 50 is shown in a simplified form organized into individual logic blocks. Each logic block further indicates a specific step, function, or sub-process that is performed by the ECU 12 of Figure 1 when Method 50 is executed.

[0039] Method 50 may be initiated after first setting up the growth process using the fiber growth machine 25 shown in Figure 1. The growth may result in the formation of a linear SCF 16 or an SCF 16 having a tapered profile as disclosed above. That is, the ECU 12 can optionally control the supply rate of the laser device 20 and / or the feed fiber 16, as understood in the art, to form a tapered profile of the SCF 16, and therefore Method 50 is not limited to the growth of a linear SCF 16.

[0040] When SCF16 begins to grow, ECU12 automatically receives a trigger signal (CC) from an external device 27 (see Figure 1). T It may be started in response to receiving a trigger signal (CC T ) indicates that monitoring and automation using the automation system 10 is initiated by a user request or autonomous request as described above. Therefore, method 50 is a digital camera 15 shown in Figure 1 that captures image data (CC IMG It starts in response to a request from ECU12 to begin collecting data.

[0041] Starting from block B52 ("Collecting Image Data"), Method 50 collects digital image data (CC) of the feed fiber 18, seed fiber 19, and molten zone 23 in Figure 2. IMG The process includes collecting ) and forming a melting zone 23 between the feed fiber 18 and seed fiber 19 using the laser beam (LL) shown in Figure 1. Subsequently, the digital camera 15 captures the image data (CC). IMG ) is output to ECU12. After that, method 50 proceeds to block B54.

[0042] Block B54 ("Receive image data") receives an image dataset (CC) from the digital camera 15 via the ECU 12 in Figure 1. IMG This includes receiving image data (CC). IMG) includes the first pixel group (P1) as described above, i.e., the feed fiber 18, seed fiber 19 / SCF16, and image pixels of the melting zone 23 in Figure 2. Block B54 uses the first camera 15A in Figure 1 to image along the first optical axis A1, and optionally, finally along the second optical axis A2, image data (CC IMG This may include using a second camera 15B (or mirror 34) to capture the optical axis A1 and optical axis A2 may be perpendicular to each other as described above. The method then proceeds to block B56.

[0043] Block B56 ("Identifying Features of Interest") may include, via the ECU 12, identifying features of interest of the feed fiber 18, seed fiber 19 / SCF 16, and / or melting zone 23 within the first pixel group (P1) in Figure 1. This action may include identifying saturated pixel clusters within the first pixel group (P1) as high-luminance pixels relative to a threshold luminance level, i.e., indicating the location of the melting zone 23 within the first pixel group (P1). In another implementation, identifying features of interest may include identifying the respective edges E1, E2 of the feed fiber 18 and the edges e1, e2 of the seed fiber 19 / SCF 16 within the first pixel group (P1). From the identified edges, the ECU 12 can identify the position of the feed fiber 18 and its inclination angle (with respect to the horizontal plane of the platform 22 in Figure 1) when the feed fiber 18 is swaying or straying toward the digital camera 15. The ECU 12 can then use this information to control the horizontal stability of the feed fiber 18. Method 50 then proceeds to block B58.

[0044] Block B58 ("Is this the second pixel group?") includes localizing one or more location-identifying pixels within the feature of interest of Block B56 as the second pixel group (P2). In embodiments of this disclosure where a saturated pixel cluster is used as the feature of interest, this action is performed on the central pixel (P2) in Figure 2. X Identify this and use it as a reference point (P REFThis may include using it to locate any position-identifying pixel.

[0045] Localizing the position-identifying pixels may also include identifying a shared or common longitudinal centerline (CL) extending between the feed fiber 18 and the seed fiber 19 / SCF 16 using each of the edges (E1, E2, e1, e2) in Figure 2. Localizing the edges in this manner may be performed by programmed operation of the ECU 12, for example, using a Canny edge detection algorithm that localizes such edges using intensity gradients or other suitable image processing techniques. As understood in the art, by using edge detection, the ECU 12 can also verify the “cone” shape of the molten zone 23. The ECU 12 can also adjust the supply and laser energy to ensure the appearance of a straight / linear conical edge rather than a curved edge. Such techniques improve the growth process and can be automated using the techniques described above. Method 50 proceeds to block B60 if one or more position-identifying pixels are successfully localized within the feature of interest. Otherwise, Method 50 returns to block B52.

[0046] In block B60 ("Controlling the Feed Fiber Position"), the ECU 12 shown in Figure 1 controls the horizontal position of the feed fiber 18 during the growth of the SCF 16 using a second set of pixels from block B58. This action sends the position control signal (CC) shown in Figure 1 to actuators 28 and 29 of the fiber growth machine 25, and ultimately to the position of the pedestal 22. P This may include transmitting ). Controlling the horizontal position of the feed fiber 18 may, in one or more embodiments, involve the reference point (P) in the saturated pixel cluster in Figure 2. REF This can be done in response to positional changes of the reference point (P REF The size and shape of the molten zone 23 in Figure 2 can be maintained so that the molten zone remains stationary.

[0047] Using the aforementioned teachings, the operator / growth operator no longer needs to manually adjust parameters in a responsive manner when attempting to maintain control over the fiber growth process. As a result, by implementing Method 50 in conjunction with the automated system 10, variability in the quality and consistency of the SCF 16 is reduced. Thus, the monitoring and control of the LHPG process for growing the SCF 16 as described above can be fully automated so that the process is self-contained, i.e., no longer requires the presence of a human operator to ensure the resulting optimal fiber quality. These and other incidental benefits of the present disclosure will be readily apparent to those skilled in the art who benefit from the present disclosure.

[0048] The features of the embodiments shown in the drawings or the various embodiments referred to herein should not necessarily be understood as independent of one another. Each of the features described in a given embodiment can be combined with one or more other desired features of other embodiments, and other embodiments not described in words or by reference to the drawings can be obtained.

[0049] Therefore, such other embodiments are included within the framework of the appended claims. While the detailed description and drawings support and illustrate this disclosure, the scope of this disclosure is defined solely by the claims. Although several aspects and other embodiments for carrying out the disclosure described in the claims have been described in detail, there are various alternative designs and embodiments for carrying out the disclosure as defined in the appended claims.

Claims

1. A method for growing single-crystal fibers (SCFs) using a fiber growth machine having one or more actuators, Receiving a set of image data from at least one digital camera via an electronic control unit (ECU), wherein the image data includes a feed fiber, a seed fiber, and a first group of pixels in a molten zone formed between the feed fiber and the seed fiber using a laser beam, The ECU is used to identify features of interest within the first pixel group, The position identification of one or more position identification pixels within the aforementioned feature of interest as a second group of pixels, During the growth of the SCF, control the horizontal position of the feed fiber in real time using the second pixel group via the ECU, including transmitting electronic position control signals to one or more actuators. Methods that include...

2. Identifying the features of interest within the first pixel group includes identifying saturated pixel clusters within the first pixel group, wherein the saturated pixel clusters have a threshold brightness level indicating the location of the melted zone within the first pixel group. Identifying the location of one or more location identification pixels includes identifying the central pixel of the saturated pixel cluster as a reference point. Controlling the horizontal position of the feed fiber in accordance with the positional fluctuation of the reference point, The method according to claim 1.

3. The method according to claim 2, further comprising maintaining the size and / or shape of the molten zone by means of the electronic position control signal via the ECU, such that the reference point remains stationary.

4. The method according to claim 2, further comprising using the ECU to control the supply rate of the laser beam and / or the feed fiber, thereby changing the size and / or shape of the melting zone to form a tapered profile of the fiber.

5. Identifying the features of interest includes identifying the respective edges of the feed fiber and seed fiber within the first pixel group, Positioning the position identification pixels includes using each of the edges to identify the common longitudinal centerline of the feed fiber and the seed fiber, Controlling the horizontal position of the feed fiber in accordance with the positional variation of the common longitudinal centerline, The method according to claim 1.

6. The method according to claim 5, wherein identifying the respective edges of the feed fiber and the seed fiber includes using a Canny edge detection algorithm.

7. The method according to claim 1, wherein receiving the set of image data from at least one digital camera includes using a first camera for imaging a first optical axis of the feed fiber and a second camera for imaging a second optical axis of the feed fiber, wherein the first optical axis of the feed fiber and the second optical axis of the feed fiber are perpendicular to each other.

8. Receiving a trigger signal from an external device via the ECU, wherein the trigger signal indicates a request to start a fiber growth process using the fiber growth machine, In response to the trigger signal, the ECU requests that the at least one digital camera begin collecting the image data, The method according to claim 1, further comprising:

9. The method according to claim 1, wherein the fiber growth machine includes a translationable platform having a plurality of actuators that can be operated collectively to move the translationable platform with two horizontal translational degrees of freedom, and controlling the horizontal position of the feed fiber includes controlling the actuators by the electronic position control signals.

10. The method according to claim 1, wherein the at least one camera includes a first camera positioned on a first optical axis and operable to collect a portion of the image data on the first optical axis, and a mirror positioned on a second optical axis perpendicular to the first optical axis, wherein the first camera is configured to collect another portion of the image data reflected from the mirror.

11. An automated system for monitoring and controlling the growth of single-crystal fibers (SCFs), A camera configured to output a set of image data including a feed fiber, a seed fiber, and a first group of pixels in a molten zone, wherein the molten zone is formed between the feed fiber and the seed fiber using a laser beam in a fiber growth machine, and the camera and An electronic control unit (ECU) that communicates with the camera, the ECU includes a processor and a computer-readable storage medium on which an instruction set is recorded, the instruction set is executable by the processor and is in the ECU, To identify the feature of interest within the first group of pixels, One or more position-identifying pixels within the aforementioned feature of interest are positioned as a second group of pixels. While the fiber is being grown by the fiber growth machine, the horizontal position of the feed fiber is controlled using the second pixel group, which includes transmitting an electronic position control signal to one or more actuators of the fiber growth machine. The aforementioned electronic control unit (ECU), An automated system, including

12. The instruction set is executable by the processor and the ECU, The feature of interest is identified by identifying saturated pixel clusters within the first pixel group, and the saturated pixel cluster has a threshold brightness level indicating the location of the melting zone within the first pixel group. The position identification pixel is located by identifying the central pixel of the saturated pixel cluster as a reference point. The horizontal position of the feed fiber is controlled in accordance with the positional fluctuation of the reference point within the saturated pixel cluster. The size and / or shape of the molten zone is maintained by the electronic position control signal so that the reference point remains stationary. The automation system according to claim 11.

13. The instruction set is executable by the processor and the ECU, By controlling the supply rate of the laser beam and / or the feed fiber, the size and shape of the melting zone are changed to form a tapered profile of the SCF. The automation system according to claim 11.

14. The instruction set is executable by the processor and the ECU, The feature of interest is identified by identifying the respective edges of the feed fiber and seed fiber within the first pixel group. The position identification pixel is located by identifying the common longitudinal centerline between the feed fiber and the seed fiber using each of the aforementioned edges. The horizontal position of the feed fiber is controlled in accordance with the positional variation of the common longitudinal centerline. The automation system according to claim 11.

15. The camera includes a first camera configured to image a first axis of the feed fiber, (i) a second camera configured to image a second axis of the feed fiber arranged orthogonally to the first axis, or (ii) one or more mirrors arranged on the second axis to direct another portion of the image data to the camera, the instruction set is executable by the processor and to the ECU, The set of image data is received from the first camera and the second camera or one or more mirrors. The automation system according to claim 11.

Images