Measuring Temperature of Optical Fiber Drawing Tower Furnace

In order to draw high quality low loss optical Fiber with the required strength and attenuation the temperature of the drawing tower furnace must be stable and precisely controlled.

The furnace lining can get close to melting point so its temperature is monitored and used as the heating control parameter.

Measurement Problems Graphite resistance and Induction-heated zirconia furnaces operating at high temperatures, typically 2200°C/4000°F, make contact methods of temperature measurement impractical.

The thermometer requires a small target size to view between the coils in an induction heated furnace, or sight down a narrow tube on to the zirconia susceptor.

In the case of a graphite resistance type furnace the thermometer has to sight through a quartz window, down through a narrow tube onto the heating element.

Experience has shown outstanding benefits by using short wavelength thermometers, for this application in order to achieve maximum accuracy.

A silicon cell detector gives high stability, rapid response and high rate of change of output with temperature.

A small target size is offered, with a measurement spot size of 4mm/0.15in diameter at the focus distance of 450mm/17.7in.

The thermometer provides high level signal to noise output for retransmission to a readout or control system.

Individually calibrated thermometers are available with traceability to National Standards. UKAS or NIST Calibration certificates are available.

Features

• 2m light guide length
• Small target capability
• Rugged, flexible, modular design
• Accurate, reliable, drift-free measurement
• Industry standard outputs to suit any process monitoring, recording or control system
• Standard industry mounting

LAND recommends:

Measuring Optical Fiber Preform Temperature

Efficient, high yield production of low loss, high bandwidth optical Fiber for telecommunication demands precise measurement and control of preform temperature during the various deposition processes employed.

The temperature of the preform in the burner zone, where the deposition takes place, is one of the critical control parameters which determines Fiber strength and transmission quality.

Measurement Problems The deposition process can be accomplished in various ways i.e. Inside vapor Deposition (I.V.D.P.), Outside vapor Deposition (O.V.D.P.), Modified Chemical vapor Deposition (M.C.V.D.).

The vapor Deposition Thermometer (VDT) must be able to sight precisely onto the rotating preform and avoid the effects of the flames, as the burner is traversed along the lathe.

Accurate surface temperature measurement can only be achieved using dedicated non contact radiation thermometers such as the LAND VDT.

Over twenty years of experience in this application has shown that thermometers operating in the waveband 4.8 to 5.2µm are the most suitable.

In this waveband, the preform is opaque and the measurement unaffected by the flames.
An accurate sighting facility and small target capability is given by focusable 100:1 optics.

Individually calibrated thermometers are available with traceability to National Standards. UKAS or NIST Calibration certificates are available.

Features

• Focusable, through-the-lens sighting - optional laser targeting is available
• Wide range of highly effective mounting accessories
• Rugged, flexible, modular design
• Accurate, reliable, drift-free measurement
• Industry standard outputs to suit any process monitoring, recording or control system

LAND recommends:

vapor Deposition - Preform Temperature