Specialty Fiber Production
Tower frame with a small footprint (1m x 1m)
Draw furnace with 0.5C temperature stability for silica or soft glass
Easily adaptable coating applicators
Large diameter wheels for large fibers
Latest generation Line Control with full production features.
And with selectable components the tower can be customized for almost any product.
Preform internal pressure control
UV and thermal curing
Wheel and belt capstans for fiber and capillary pulling
Polyimide and Acrylate coatings
Take-up options up to 1m diameter reels.
Nextrom also provides process support for different products such as PM, PCF, LMA, Thin Fibers, different coatings and more making us the complete supplier for specialty fiber production.
FURNACE POWER CONTROL UPDATES
Recent improvements in the NEXTROM Specialty Fiber Drawing Furnace (fig.2) power supply and control system have resulted in industry leading quality and temperature stability. By upgrading the control system with state-of-the art thyristor controllers and implementing a revolutionary software control system, the latest system is able to maintain a stable furnace temperature to less than +/-0.5 C while operating in excess of 2100C even in conditions where the supply power network experiences voltage fluctuations. The system includes constant incoming power monitoring as well as high speed bus communication to the PLC which allows for extremely fast regulation of the power set-point in order to compensate for any variations in the incoming line power. The result is an extremely stable furnace temperature producing the highest quality fiber, with minimum diameter variation.
PHOTONIC CRYSTAL FIBER PRODUCTION
The photonic crystal fiber (PCF) (fig.3) market has grown with new applications such as sensing, supercontinuum generation, and high power lasers, to name a few. In order to maintain a proper internal structure it is important to regulate the pressure inside the preform and fiber. Nextrom’s high performance Preform Pressure Control System (PPCS) (fig.4) achieves this with a mix of high quality components and innovative control loop feedback. Each pressure line consists of a high accuracy mass flow controller, vacuum pump, bleed valve, pressure accumulator tank, and high accuracy pressure transducer. The needle valves are adjusted to maintain a small, repeatable leakage to ensure that the mass flow controller flow rate is maintained within its ideal operating range and based on the pressure transducer measurement, Nextrom’s advanced PID control loops adjust the mass flow controller flow to accurately maintain the pressure set point. The result is a system which can control and maintain the pressure to within +/-0.1 mbar even with the changing preform temperatures. In addition, the system can be configured to have multiple, independently regulated pressure lines for individual control in different regions inside the preform.
In addition to top of the line equipment, Nextrom’s process engineers have commercial PCF production experience and are available to assist in the whole PCF process to shorten the learning period for new producers or improve the quality for existing producers.
Spinning the preform during the draw results in a polarization maintaining fiber in both the linear and circular directions that can be used in fiber optic current sensors (FOCS). The design of the spinning chuck and related bearings is critical to maintain proper chuck alignment and concentricity while operating in the high temperature zone above the drawing furnace. The temperature of the bearings can rise hundreds of degrees from room temperature and proper design is essential to smooth rotation and long bearing lifetime. Nextrom realized this requirement and worked extensively with leading bearing manufacturers to design and calculate the proper bearing types, clearances, and preloads to ensure proper operation throughout the temperature range. This resulted in a spinning system (fig.5) with a runout of less than 0.05mm at the chuck end. The minimized runout produces the highest quality spun optical fibers and increases the safety of the operator.