The utility model discloses an
optical film thickness
monitoring system based on an FPGA (
Field Programmable Gate Array), which belongs to the field of
optical film coating and comprises an
optical path and a circuit, the light path comprises a
light source, a light
chopper, a
beam splitter, a monitoring piece and a
monochromator, the circuit comprises a
photoelectric conversion board and an FPGA development board, the light path part is responsible for generating and modulating light signals, the circuit part is responsible for
signal conversion, amplification,
demodulation,
noise filtering and extreme point interpretation, on the FPGA development board, a
digital signal processing technology is utilized, a reference
signal is used as a benchmark, and the
optical path part and the circuit part are integrated. The main
signal is demodulated, in the
demodulation process,
noise and interference caused by factors such as environment and equipment can be eliminated, some
noise and interference still exist in the demodulated main signal, the FPGA development board can further filter out the noise and improve the signal-to-noise ratio of the signal, and the extreme point of the main signal subjected to noise filtering
processing corresponds to the change of the thickness of the film. The
algorithm on the FPGA development board can accurately interpret the extreme points, so that the change information of the film thickness is obtained, the change of the film thickness can be more accurately identified, and the monitoring precision is improved.