Due to the high dependence of our thermal emission characteristics on the wavelength of the thermal radiation due to the extreme dependence of our thermal emission behavior on the wavelength, only certain wavelengths are effective for thermal measurements. The following diagrams illustrate the range of thermal transmission for common windows and thermal lenses for infrared thermometers. The blue-colored curve demonstrates the general rule applicable to all materials and represents the average value over an interval of temperature from zero (black) to infinity (green), which is known as 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 across the viewing angle for given viewing angle and cte of a lens or window. The bending moment of a system is the variation in the angle of incidence, which is linear or spherical. This causes the slope to be proportional to this curve. The focal length of a system is also a factor in the slope. This can be thought of as a function the focal length divided by the length of the curve (i.e. the interval between shots).
For a particular set of temperatures and a given focal length of a lens or window assembly, the internal surface temperature of the system will always fall within the prescribed range in a perfect regularity called a “curved surface.” The thermal conductance curve of a glass bead within a glass vial can be plotted in relation to the focal length as well as the temperature difference between the bottom and the surface of the vial and the angle of incidence of a particular window. If the aperture is fixed for all shots, then the area between the system’s surface temperature and the curve of variation should remain constant. If the aperture is variable, then the curve may be curved as a result of the variation in the temperature of the glass used to create the bead and the temperature of the ambient air that is circulating on the inner surface of the vial, and the focal length and duration of shooting. An example of a curved surface can be seen in the signature left by a photographer of the flower.
A window and lens should be mounted so that their focal points and lines of sight are correctly aligned. If the temperature of the inside of the system is too cold for the lens, then the outside surface temperature of the frame will be cooler and the inside of the lens will be too hot. If the temperature outside of the lens and the frame are equally and the frame is at the same temperature, it will not require any adjustments to compensate for the heating or cooling effects of internal temperature differences. The inside surface temperature of the frame will be in line for a given focus length without the need for any other adjustments, provided that there is no external source of temperature variations impacts the system. If the system is situated in an area that has restricted or blocked views of surrounding structures or landscape it could be necessary to control internal temperatures.
The first mechanical interlocking system used to attach camera lenses were made out of plastic. This technology was later adopted for use with pinhole glasses. This type of lens assembly is not without a problem: the mechanical joints between the frame and the lens could crack or indent. In the event of this occurring, it would be essential for the entire system to be replaced in the shortest amount of time. Because of this, this type of system has been replaced with more robust designs.
Pinhole glasses lenses are generally made with a metal frame and a thin, glass or plastic lid. At the very least the lense designs should include a hermetically sealed lens construction. A hermetically sealed lens construction has a sealed surface on the top and bottom of the lens assembly. The top surface may have a similar mechanical seal to the one described above. It could also be a source of adhesive, lip or a layer of plastic film.
Another variant of window and lens assembly is to have an lens surface that is a substratethat is attached to the base of the window assembly. This kind of system usually consists of a window casing and several lens compartments. Other kinds of devices can be included in the windows, for example, thermometers and light emitters. In some cases, the device that controls the temperature within the room might also be part of this kind of system. A number of compartments could be used to house the temperature control and a range of other devices like an alarm clock, thermostat, or other devices.
This isn’t a complete listing of all the types of window assemblies and lenses that are available. It’s a good indication of the significant technologies that are connected to this invention. Please refer to the complete disclosure for more information. Refer to the sections that pertain to “details about the invention” and “Description of the Method with Respect To the Identification of the Different Classes of Products which are involved in the Present Application.”
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