Abstract: A cam filter wheel apparatus is disclosed for tilting interference filters in order to achieve variation in the light wavelength transmitted by each filter. The wheel apparatus contains a number of filters each mounted so as to pivot and change its inclination with respect to an incident light beam as the filter wheel rotates each filter through the light path. The pivot motion is achieved by a cam follower associated with each filter which rides on a stationary cam track.

Abstract: Apparatus for determining the nitrogen oxide concentration in a gaseous mixture while minimizing measuring errors. The radiation from a hollow cathode lamp emitting the nitrogen oxide resonance radiation is modulated by a device for generating alternatively an unfiltered or test beam and a reference beam. The reference beam is filtered by a nitrogen oxide filled filter. An absorption cell is disposed in the path of the reference beam. Further, a monochromator or filter is provided and a detector for receiving the radiation from the monochromator filter. A signal processing unit is coupled to the detector for forming electric signals corresponding to the signal from the unfiltered and the reference beam and for forming the quotient thereof. A ray splitter is disposed in the path of the two beams to provide a different beam path and an additional radiation detector is disposed in the additional path.

Abstract: A method for determining the quantity ratio of two components of a multi-substance mixture whose absorption bands are adjacent to each other and overlap comprises using an interference filter which is rotated in a uniform rotation about a first axis through the filter plane which forms with a perpendicular erected on the filter plane a fixed angle .beta. which is not equal to zero. The filter is rotatably arranged about a second axis through the filter plane and the method is characterized by adjusting the angle .alpha. which the axis of rotation forms with the ray in the range of .beta. is less than .alpha. so that a signal corresponding to the first derivative of the spectral intensity distribution of the radiation transmitted by the substance mixture just passes through zero and a quantity correlated with this angle is used as a measure of the quantity ratio.

Abstract: In an illustrated embodiment, brightness, color, opacity and fluorescent contribution to brightness of single thickness sheet material are measured by an optical measuring system providing for simultaneous measurement of transmitted and reflected light. One embodiment is designed so as to be capable of transverse scanning of a moving paper web on the paper machine. An optical window member of translucent diffusing material serves as a backing for the web for reflectance measurements and is in series with the web with respect to transmittance measurements. The optical window itself is selected as to its reflectance and transmittance so as to provide for periodic standardization of the instrument in an off-sheet position. Another embodiment will measure the same optical properties of single thickness sheet material selectively, with spectral response filters for characterizing such optical properties and with a series of narrow band filters.

Abstract: A photo-reconnaissance/surveillance system in which the landscape to be sned is photographed on color film. The film is then developed in a highspeed processor and scanned by photosensors. Illuminations for the sensors is provided by a plurality of point sources of light. Colored filters e.g., a green filter and a blue filter, are alternately interposed between the light sources and the film. A logic circuit compares the transmission through the film for both light conditions and, thus, can detect the presence of a target, if the color signature of the target is known a priori.

Abstract: A three ingredient mixture is eradiated with light rays of two separate wave lengths selected at which the absorption spectra of at least two of the materials of the mixture intersect. The light rays passing through the materials are detected and separated electrically so that they are processed with coefficients determined from ratios involving the absorption of at least two of the materials, so that the difference in the signals so obtained is quantitatively correlated to only one of the materials in the mixture.

Abstract: A tristimulus colorimeter employs a multiplexed dual slope integrator digital voltmeter wherein unknown and reference light beams are compared by sequentially applying unknown and reference electrical signals representative of the two respective light beams to the non-inverting and inverting inputs, respectively, of the integrator amplifier. Moreover, a compensating circuit provides for compensation of the colorimeter output signals with respect to reflectance error encountered in the optics portion of the colorimeter with such compensation being provided as a function of the light intensity from the colorimeter light source.

Abstract: A tristimulus colorimeter employs a multiplexed dual slope integrator digital voltmeter wherein unknown and reference light beams are compared by sequentially applying unknown and reference electrical signals representative of the two respective light beams to the non-inverting and inverting inputs, respectively, of the integrator amplifier. Moreover, a compensating circuit provides for compensation of the colorimeter output signals with respect to reflectance error encountered in the optics portion of the colorimeter.