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JP-2026514465-A - Automatic control of single-crystal fiber growth process

JP2026514465AJP 2026514465 AJP2026514465 AJP 2026514465AJP-2026514465-A

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 location-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.

Inventors

  • ケビン カンツォーネ
  • ジゼル マクスウエル
  • アンドレイ ディーブ

Assignees

  • アルコン インコーポレイティド

Dates

Publication Date
20260511
Application Date
20240313
Priority Date
20230412

Claims (15)

  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 via the ECU using the electronic position control signal, so 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 and thereby forming 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 fiber growth machine comprises a translationable platform having a plurality of actuators collectively operable to move the translationable platform with two horizontal translational degrees of freedom, and the control of the horizontal position of the feed fiber includes controlling the actuators by the electronic position control signals, according to claim 1.
  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.

Description

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. Laser beams are used in countless scientific and medical applications requiring 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 approximately 0.05 to 2 meters and a small diameter of less than approximately 500 microns. 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. Figure 1 shows an exemplary embodiment of an automated system for monitoring and controlling the growth of single-crystal fibers (SCFs) as described herein.Figure 2 is a simplified diagram of a typical melting zone during SCF growth.Figure 3 is a flowchart illustrating one embodiment of a method for monitoring and controlling the growth of the SCF in Figure 2 using the automation system shown in Figure 1. The solutions presented in this disclosure may be modified or presented in alternative forms. Representative embodiments of this disclosure are shown in the drawings as examples and are described in further detail below. However, the inventive aspects of this disclosure are not limited to the embodiments disclosed. Rather, this disclosure is intended to encompass alternative forms that fall within the scope of this disclosure as defined by the appended claims. Embodiments of this disclosure are described herein. However, it should be understood that the embodiments disclosed are merely illustrative, and other embodiments may take various alternative forms. The drawings are not necessarily to scale. Some features may be exaggerated or minimized to illustrate the details of certain components. Therefore, certain structural and functional details disclosed herein should not be constrained, but rather should be interpreted merely as representative grounds to teach those skilled in the art how to employ this disclosure in various ways. 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. 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, consistent with 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. 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