While many fibre-optic parts are still hand-assembled, the Albuquerque division of LightPath Technologies designed an integrated, automated approach to produce collimators, which are gradium lenses fused to fibre-optic cable that help direct light. The performance and reliability of these intricate parts are integral to the overall performance of telecom systems.
With an automated system approach, gains in efficiency resulted in producing more collimators in less time. The system was based on the National Instruments' PXI platform along with MXI-3 for additional slot capability, and included National Instruments motion, vision, DAQ, signal conditioning, and LabWindows/CVI, a component of Measurement Studio. With these systems, technicians could perform various positioning, fusing, and cutting tasks required in the collimator manufacturing process.
From the R&D lab to the production floor
The first system was developed in the lab, and is still used today for making tweaks and enhancements to the factory floor system. Building these complete systems goes quickly, and building them on PXI proved seamless.
The production floor, housed in a clean room environment, has an array of workstations with extra space for additional machines. The PXI chassis holds machine vision (IMAQ), motion control, DAQ, and GPIB hardware. Two monitors, driven by a computer, display the visual results. The motion controllers, cameras, and signal conditioning are housed in a black box, which also contains all the mechanical equipment used in the manufacturing process.
The fusing machine works by threading fibre-optic cable down from a large spool to small roller blade wheels, using motion control to fine-tune the cable position. From there, a laser welds the cable with the lens - this patented laser process takes about a minute per collimator. NI vision products ensure precise alignment between the lens and the laser. The entire system uses three cameras along with two different vision boards. A digital camera and board combination looks at the beam coming out of each collimator, then performs feedback diagnostics and obtains quality control on the end product. This quality check ensures that the system spots any defects immediately.
Other CCD cameras look at the angle between each fibre and lens combination, measuring and adjusting the angle to see if it lies within certain tolerances. LightPath has set up process control parameters for this system, determining what is acceptable and what is not. IMAQ hardware and software ensure that these parameters are met.
Data acquisition boards perform diagnostic tests on the overall system, including measuring encoder feedback, digital I/O for the relays, and performing other measurements to ensure the process lies within the accepted parameters.
Similar system performs polishing
A second system using motion, vision, and data acquisition, based on the machines used in the production floor, performs coating and polishing functions on the lenses before they reach the automated test process. It was found to be simpler to borrow the technologies already invested in the manufacturing test stations to perform the required polishing tasks. The polishing system is quite fast, taking only about three seconds per lens to position, move, and inspect each part.
Ease of integration
One of the main benefits of its system is that the user could develop a custom solution with all the tools it needed, from motion, to vision, to data acquisition, gaining test flexibility and reliability in the process. If changes need to be made to the system, LightPath Technologies is able to implement them from a central office, making it easy to perform tweaks on the fly. Throughout the system development, Lighpath Technologies has improved its control and completed a system that is robust and solid.
National Instruments
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