Abstract: Devices and methods for measurement of energy from a defined source having increased accuracy in measuring low energies. The device comprises a housing containing sensors. A first sensor receives energy from the source and produces a first output. A second sensor receives ambient energy only and produces a second output. Subtraction of the second output from the first output produces a more accurate corrected output. The method includes providing a housing containing a first sensor and a second sensor and directing energy from the defined source to a surface of the first sensor thereby causing the first sensor to produce a first output while only ambient energy from sources other than the defined source is applied to a surface of the second sensor which produce a second output that is subtracted from the first output producing a corrected output.

Abstract: A precision optical element is described, such as is used in thermal imaging systems in the infrared, manufactured by means of single point machining, with both of its surfaces having an aspheric form, with or without the addition of a diffractive optics pattern. The element is produced while held in a novel vacuum chuck, whose support surface has a width in the radial direction significantly less than the size of the element, and which is aspherically machined to match the aspheric first surface of the element. A method whereby such an element can be produced by means of single point machining, such as diamond turning or fly cutting, is also described. Also described are new optical system designs and applications using such double-sided aspheric elements, thereby providing significant improvement over currently available optical systems.

Abstract: A precision optical element is described, such as is used in thermal imaging systems in the infra-red, manufactured by means of single point machining, with both of its surfaces having an aspheric form, with or without the addition of a diffractive optics pattern. The element is produced while held in a novel vacuum chuck, whose support surface has a width in the radial direction significantly less than the size of the element, and which is aspherically machined to match the aspheric first surface of the element. A method whereby such an element can be produced-by-means of single point machining, such as diamond turning or fly cutting, is also described. Also described are new optical system designs and applications using such double-sided aspheric elements, thereby providing significant improvement over currently available optical systems.

Abstract: A dispersive spectrometer whose dispersive element is aligned such that the direction of dispersion is essentially perpendicular to the collimating plane, which is the plane of the input beam path between the centers of the input slit, the collimating mirror and the dispersive element. As a result of this construction, the lateral spread over which the beam path traverses is reduced, since use is also made of the direction perpendicular to the input beam path plane for the dispersive spread of the beam, and the spectrometer is thus of compact construction.

Abstract: An optical aiming device including two optical elements, each characterized by a refractive index and a critical angle defining a total internal reflection plane, positioned one in front of the other substantially along an aiming axis, each optical element causing a portion of light impinging thereon at an angle greater than the critical angle, to be reflected, thereby defining a demarcation between a region of reflected light and non-reflected light, the optical elements being oriented such that the demarcations of each optical element intersect at a point lying substantially along the aiming axis.

Abstract: A technique for performing background suppression in photodiode detectors is disclosed. A first detector measures the light emitted by the source to be measured and the background light, while a second detector simultaneously measures the background light only. The value measured by the second detector is subtracted from the value measured by the first detector, and the difference represents the portion of the first detector's measured value which is attributable to the source to be measured.

Abstract: Pyroelectric detection apparatus including a pyroelectric detector operative to produce an electric output in response to pulsed incident radiation and a discharge circuit for discharging the electric output. The discharge is operative to impose an effective high impedance on the pyroelectric detector during at least a portion of the duration of each radiation pulse and to impose a low effective resistance during the intervals between the radiation pulses.