A gas analysis system and method filter different wavelengths of incident light using a variable light filter at different locations along a length of the variable light filter to form filtered light. The variable light filter is configured to be disposed between a light source generating plural different wavelengths of the incident light and a gas sample. Intensities of wavelengths of the filtered light are determined after the incident light generated by the light source passes through the variable light filter and the gas sample. The gas sample may be identified from among different potential gasses based on the intensity of the one or more wavelengths of the filtered light that is determined by the light detector.

A digital imaging device includes: a monochromatic sensor including a plurality of photosensitive elements distributed in an array, the plurality of photosensitive elements configured to convert light falling on the monochromatic sensor into electronic signals; and a plurality of filters, each filter configured to be moved into a position in front of the monochromatic sensor, wherein each filter, when moved into the position in front of the monochromatic sensor, covers substantial portion of the monochromatic sensor. Key words include imaging sensor and layered filter.

A method for detecting a molecule in a sample includes applying a first filter to an image at a first wavelength. The method also includes applying a second filter to the image at a second wavelength. The method also includes applying a third filter to the image at a third wavelength. The first, second, and third wavelengths are within a predetermined wavelength range, and wherein first, second, and third wavelengths are different from one another. The method also includes detecting a spectral signature for the molecule in the sample in the image after the first, second, and third filters are applied to the image. The method also includes determining whether the molecule is present in the sample based at least partially upon the detected spectral signature.

A method for detecting an aflatoxin on a seed which includes determining wavelengths at which there is greatest difference in reflectance intensities of control and contaminated seed, and comparing reflectance intensities from the captured image with reflectance intensities indicative of an aflatoxin presence at a predetermined concentration. Seeds are ejected that have an aflatoxin concentration greater than the predetermined concentration as indicated by the reflectance intensities from the captured images. Examples of seeds include a nut or legume.

The concentration of one or more gases in a surrounding fluid is measured using apparatus having a gas-permeable membrane separating an enclosed internal space within the apparatus from the surrounding fluid while allowing gases to diffuse from the surrounding fluid into the internal space. One or more sources sends infrared radiation along optical paths to one or more infrared detectors measuring intensity of radiation after absorption by gas(es) in the internal space and concentrations are determined from measured absorptions. The apparatus has more than one optical path through the internal space, enabling measurements of concentration over a greater range or enabling measurements of more than one gas present in very different concentrations or having very different infrared absorptivities.