This application uses a Fiber Sensor that resists cleaning liquids and a Fiber Amplifier that eliminates the effects of drops of water. This Fiber Sensor detects passage of glass substrates in the cleaning process of glass substrates. This Sensor resists cleaning liquids and does not need mechanical adjustments to enable easy positioning adjustments with glass in a wide detection area. A special Fiber Sensor that mounts the new 'Tough Mode' eliminating interference from water droplets enables stable detection that resists the spray of liquids.