Patent ID: 7600431

Claim:
A method for manufacturing closed, filled containers transparent to laser light, the pressure of a gas species therein being monitored, comprising: manufacturing a closed, filled container transparent to said laser light; exposing said container to transmission of laser light; providing said laser light with wavelengths spread over a wavelength band including at least one absorption line of said gas species; optoelectrically converting said transmitted laser light, thereby generating an electric output signal; inputting a signal dependent on said electric output signal to at least a first and a second gas pressure monitoring channel; performing in said first channel first filtering; performing in said second channel second filtering; performing said first filtering so that the output signal of said first filtering varies with a first characteristic as a function of said pressure; performing said second filtering so that the output signal of said second filtering varies with a second characteristic as a function of said pressure; said first characteristic being different from said second characteristic; evaluating from combining signals dependent on the output signals of said first and second filtering said pressure indicative signal.