| 摘要 |
An entrance aperture of a GFCR system receives light from a scene of interest. The light is focused to form an image at a focal plane. Light associated with a selected field-of-view of the image is then confined to a spectral band at which a gas of interest absorbs. The confined light is split into first and second paths. A region that does not substantially interfere with the spectral band is disposed in the first path. A first two-dimensional array of optical detection elements is disposed in the region along with a first diffuser. The first diffuser assures that each portion of the light from the selected field-of-view of the image is identically distributed across the first array. A gas cell filled with the gas of interest, a second two-dimensional array of optical detection elements, and a second diffuser are disposed in the second path. After the collimated light is passed through the gas cell, the second diffuser assures that each portion of the light from the selected field-of-view of the image is identically distributed across the second array. The first and second optical arrays generate output signals that are summed to form corresponding first and second sums. A difference between the first and second sums is generated and normalized as a direct measure of the gas of interest.
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