<p>Photographic coating process monitor. Moving web still wet from the coating process is monitored for streaks by passing under a head with a lamp and focussing system which moves across the web. A p.e. transducer transmits the reflected light to an amplifier feeding a discriminator which passes fault signals to a fault recording device. The lamp is an i.r. ribbon lamp with a filament 20 mm long and 0.2 mm thick, emitting light within the range of wavelengths of water absorption of about 2 microns.</p>
