Laser Melt Control System
Precise closed loop positioning of the
silicon melt.
Our system features a sensor assembly
consisting of the following components:
- Diode Laser Emitter Unit
- Photodetector Receiver Unit
- Signal Processing Electronics
- Protective Housings and Shielding
The laser beam reflects off the melt
surface and is captured by a sensor that converts the beam
position into an electrical signal for the controller. The
control software initializes the melt level position with
crucible position data that is corrected by laser sensor
data.
Standard Specifications
Laser
Certified Class II system: 1mW maximum, 670 nm (visible
beam); emitter de-energized when furnace tank cover is lifted.
Sensor
75mm diameter front aperture with compact lens reimaging
system and linear position sensing photodetector.
Electronics
Modulated laser beam with synchronous signal detection for
complete rejection of background radiation interference.
Range
Initial mechanical positioning range of + 50 mm from nominal,
with an electrical dynamic range of + 20 mm from the mechanical
position.
Accuracy
+ 0.5 mm repeatability of initial position and an electrical
repositioning accuracy of +1.0 mm within the +20 mm electrical
dynamic range, when calibrated using the Kayex computer
linearization program.
Resolution
+0.1 mm - allows holding initial melt position within +0.5
mm when combined with the Kayex modified CL/SL ratio control
program.
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