Tandem-type collimator pair, and manufacturing method and application thereof

The invention discloses a tandem-type collimator pair. At least two grooves are formed in a collimator base; a left collimator and a right collimator which are opposite to each other are arranged in each groove to form a unit collimator pair; tail optical fibers of adjacent two unit collimator pairs are connected in series with each other; and the tail optical fiber of the left collimator of the first unit collimator pair and the tail optical fiber of the right collimator of the last unit collimator pair are led out. According to an optical fiber gas sensor manufactured by adopting the tandem-type collimator pair, light rays enter a spectrum analyzer or a gas detection device after emitting out from the tail optical fiber of the last collimator; when a gas to be detected passes through tandem-type collimator pair, gas absorption intensity changes, and parameters of the gas can be determined by detecting the relative change rate of the gas absorption intensity; a gas absorption law can be validated; the concentration of the gas can be detected; the tandem-type collimator pair is high in sensitivity, high in response speed and large in dynamic range; and the optical fiber gas sensor using the tandem-type collimator pair is accurate in detection.