Electrically modulated light source, non-dispersive infrared spectrum detection system and method for detecting gas using the same

A non-dispersive infrared spectrum detection system comprising:

• a vacuum chamber comprising a window;
• a first window piece fixed at the window;
• a gas chamber directly connected to the first window piece, wherein a side of the gas chamber at the first window piece is defined as a first side, and a side of the gas chamber opposite to the first side is defined as a second side;
• a second window piece fixed on the second side;
• a narrow bandpass filter;
• a detector;
• and
• an electrically modulated light source comprising a carbon nanotube film structure and isolated from a gas in the gas chamber, wherein the electrically modulated light source is capable of heating up to a highest temperature to emit a thermal radiation in less than 10 milliseconds after a voltage is applied, and the electrically modulated light source is capable of cooling down to an initial temperature of the electrically modulated light source in less than 10 milliseconds after the voltage is removed;
• and an modulation frequency of the electrically modulated light source is greater than or equal to 150 KHz,
• wherein an optical signal radiated by the electrically modulated light source is detected by the detector after sequentially passing through the first window piece, the gas chamber, the second window piece, and the narrow bandpass filter.

A method for detecting gas, comprising:

• step (S1):
• providing a non-dispersive infrared spectrum detection system comprising:
• a vacuum chamber comprising a window;
• a first window piece fixed at the window;
• a gas chamber directly connected to the first window piece, wherein a side of the gas chamber at the first window piece is defined as a first side, and a side of the gas chamber opposite to the first side is defined as a second side;
• a second window piece fixed on the second side;
• a narrow bandpass filter;
• a detector;
• and
• an electrically modulated light source comprising a carbon nanotube film structure and isolated from a gas in the gas chamber, wherein the electrically modulated light source is capable of heating up to a highest temperature to emit a thermal radiation in less than 10 milliseconds after a voltage is applied, and the electrically modulated light source is capable of cooling down to an initial temperature of the electrically modulated light source in less than 10 milliseconds after the voltage is removed;
• and an modulation frequency of the electrically modulated light source is greater than or equal to 150 KHz,
• wherein an optical signal radiated by the electrically modulated light source is detected by the detector after sequentially passing through the first window piece, the gas chamber, the second window piece, and the narrow bandpass filter;
• step (S2):
• injecting a gas to be detected into the gas chamber;
• and
• step (S3):
• applying a voltage to the electrically modulated light source, to make the electrically modulated light source emit thermal radiation, and a optical signal radiated by the electrically modulated light source is detected by the detector after sequentially passing through the first window piece, the gas chamber, the second window piece, and the narrow bandpass filter.