Due to the dependence of our thermal emission characteristics on the wavelength of the thermal, only a few wavelength ranges are suitable for thermal measurements. The following diagrams illustrate the thermal transmission range of common thermal lenses and window substances for infrared thermometers. The blue-colored curve illustrates the general rule applicable to all materials and represents the average value for an interval of temperature from zero (black) to infinity (green) which is the cold-pressure limit (CPL).
The cold-pressure limit, which is used to determine the thickness of windows and lenses is the highest measured value of a material’s damping coefficient against the thermal gradient. This ratio is calculated as a function of the temperature difference along a viewing angle for a given viewing angles and cte of a lens or window. The bending moment of a system is the variation in angle of incidence from linear or spherical. This causes the slope to be proportional to the curve. The slope of this curve is also proportional to the focal length of the system, which can be described as an expression of the focal length divided by the length of the curve (i.e. the interval between shots).
For a particular set of temperatures and a specific focal length of a lens or window assembly, the inside surface temperature of the system will always fall within the prescribed curve , in a perfect regularity called a “curved surface.” For instance the curve of thermal conductance of a glass bead inside a glass vial that has a hole in it can be plotted in relation to the focal length and the temperature difference inside the vial between the bottom of the bead and the surface of the vial, and the angle of incidence for a specific window assembly. If the aperture is fixed for all shots, then the area between the system’s surface temperature and the curve of variation should remain the same. If the aperture is adjustable and the curve is not fixed, then it could be curved as a result of the fluctuation in the temperature of the glass used in the making of the bead as well as the temperature of the ambient air that is on the inside surface of the vial, and the focal length as well as the duration of shooting. A signature left by photographer on the petals of a flower is an example of a curved surface.
A window and lens should be mounted in a manner that their focal points and lines of sight are properly aligned. If the surface temperature of an object is too cold for the lens, the exterior temperature of the frame and its interior temperature will be too high. The frame will not have to be adjusted to compensate for internal temperature variations or cooling effects. The inside surface temperature of the system will be appropriate for a given focus length without the need for any other adjustments, provided that there is no external cause of temperature variations affects the system. However, if the system is installed in a location with an obstruction or limited view of any nearby building or scenery and the surrounding area, then internal temperatures might need to be controlled.
The first mechanical interlocking mechanism used to mount lenses to camera were made out of plastic. This design was later used for pinhole glasses. One issue with this type of lens assembly is that the mechanical joints between the lens and frame might indent or even fracture. If this happened then it would be necessary to replace the entire system in a relatively short period of time. Due to this the type of system has been replaced by more robust designs.
Lenses made to work with pinhole glasses typically come with frames made of metal and an elongated glass or plastic lid. These lense designs should at the very minimum have a hermetically-sealed construction. A hermetically sealed lens construction has an enclosed surface at the bottom and top. The top layer could be a part of a mechanical seal that is similar to that previously mentioned. It could also be a source of adhesive, lip or a layer of plastic film.
A lens surface that has an adhesive and is bonded to the base is an additional example of this type of lens and window assembly. This type of system is typically comprised of a window casing and a series of compartments for lenses. Other kinds of devices can be included in the windows, like light emitters and thermometers. In some cases, the device used to regulate the temperature of the room might also be part of this kind of system. A number of compartments could be used to house the temperature controller and a range of other devices such as an alarm clock, thermostat, or other devices.
This isn’t an exhaustive list of all kinds of lens assemblies and windows. However, it is indicative of the key technologies that are associated with this invention. For more information, see the entire disclosure. Please refer to the sections on “details regarding the present invention” and “Description of the Method with Regard to the Identification of the Different Classes of Products That Are Involved In the Present Application.”
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