VDT

Vapour Deposition Thermometer

Efficient, high yield production of low loss, high bandwidth optical fibre 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 fibre strength and transmission quality.

Key Features & Benefits

  • 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.

Measurement Problems
The deposition process can be accomplished in various ways i.e. Inside Vapour Deposition (I.V.D.P.), Outside Vapour Deposition (O.V.D.P.), Modified Chemical Vapour Deposition (M.C.V.D.).
The Vapour 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 5.2 µm 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 given by focusable 100:1 optics.
Individually calibrated thermometers are available with traceability to National Standards. UKAS or NIST Calibration certificates are available.

Technical Details
Vapour Deposition Thermometer System – Single and Multiple Thermometers with LANDMARK GRAPHIC Signal Processor
Model:
VDT-S 1000/2500C
VDT-S 1800/4500F
Temperature range:
1000 to 2500°C
1800 to 4500°F
Wavelength:
4.8 to 5.2µm
Averager response time:
100ms
Output:
4 to 20mA
Sighting:
Target size:
Magnification:
6°, through the lens
>98% of energy within graticule image
1.8x
Eye relief:
30mm/1.2in
Field of view (Nominal):
100:1
Minimum target size:
3.5mm diameter/0.13in diameter
Focus range:
0.35m to 1m/13.6in to 39.4in (Variable focus)
Accuracy Repeatability:
Absolute:
1K
0.5%K
Stability Temperature:
Time:
<0.02%K/K
2°C/4°F/year
Power supply:
23 to 48V d.c., <200mA
Vibration:
3g any axis, 60 to 300Hz
Humidity:
0 to 99% non condensing
Sealing:
To IP65 requirements
To NEMA 4X requirements
Ambient temperature
Specified:
Operating:
0 to 70°C/32 to 158°F
-10 to 80°C/ 14 to 176°F
CE:
EN 50-082-2 (immunity), EN 50-081-1 (emission), IEC 1010 (safety)
Vapour Deposition Thermometer – Stand Alone Thermometer
Model:
VDT-U 1000/2500C
VDT-U 1800/4500F
Temperature range:
1000 to 2500°C
1800 to 4500°F
Wavelength:
4.8 to 5.2µm
Averager response time:
Adjustable 100ms to 5s (0 to 95%)
Peak picker:
Adjustable 1.5 to 30%/s decay
Emissivity:
Adjustable 0.10 to 1.00
Output:
4 to 20mA
Sighting:
Target size:
Magnification:
Eye relief:
6°, through the lens
>98% of energy within graticule image
1.8x
30mm/1.2in
Field of view (Nominal):
100:1
Minimum target size:
3.5mm/0.13in diameter
Focus range:
0.35m to 1m/13.6in to 39.4in (Variable focus)
Accuracy Repeatability: Absolute:
<1°C/<2°F
0.6%K
Stability Temperature:
Time:
<0.025%T(K)/K
2°C/4°F/year
Power supply:
23 to 48V d.c., <200mA
Vibration:
3g any axis, 10 to 300Hz
Humidity:
0 to 99% non condensing
Sealing:
To IP65 requirements
To NEMA 4X requirements
Ambient temperature
Specified:
Operating:
0 to 70 °C/32 to 158 °F
-10 to 80 °C/14 to 176 °F
CE:
EN 50-082-2 (immunity), EN 50-081-1 (emission), IEC 1010 (safety)

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