Filters for gas analysis and detection
（Gas analysisi and detctions)
This section introduces our filters for use in gas analysis and detection.
Principles
There are several methods for analyzing and detecting gases. One of those methods is infrared absorption, which uses an optical filter. Figure 1 shows the configuration of an infrared absorption gas sensor. There is a light source placed on one side of the sample chamber and a light receiving section placed on the other side. An optical filter is placed in front of the light receiving section. The gas to be measured is made to flow through the sample chamber. Many gases have the characteristic of absorbing light at a peculiar wavelength in the infrared region (Table 1). Therefore, when gas enters the measurement chamber, the light from the light source that is in the absorption region of the gas is absorbed by the gas and the transmittance decreases. The photodetector detects the amount of light arriving from the light source to determine the quantity of the gas. However, a photodetector is sensitive in a wide range of wavelengths, so if it is used alone, it is possible to detect the presence of gas, but not to distinguish between gas types.
Optical filters are used to identify different gas types. For example, if it is necessary to selectively detect methane gas, then a filter is installed on the light-receiving section to selectively transmit 3.3 μm light, which is the absorption edge of methane. As a result, the light-receiving sensor section will not detect any light other than 3.3 μm. Therefore, methane gas can be detected with high selectivity, even if is mixed with other gases.
Features
The gas to be detected, the concentration, and the surrounding environment vary from customer to customer.
We respond to the requirements of the customer with individual support for each of the items below.
Spectroscopic characteristics: Transmission band (half-width, maximum transmittance), stop band (wavelength range, stopping performance)
Material: Ge, Si, sapphire, quartz, etc.
Size: Square, round
Quantity: We support anything from one filter to mass production.
Durability: Our products can be cut for use.
They can be delivered in the wafer state and then cut by the customer for use. We can also cut them before delivery.
Quality assurance: We meet your needs.
Constant temperature and humidity tests, heat cycle tests, heat resistance tests, boiling tests, adhesion confirmation tests
Applications
Gas analysis, gas alarms, gas detectors
Example characteristics
