Due to the high dependence of our thermal emission characteristics on the wavelength of the heat source due to the extreme dependence of our thermal emission behavior on the wavelength, only certain wavelengths are effective for thermal measurements. The following graphs show the thermal transmission ranges of common window and thermal lenses for infrared thermometers. The blue-colored curve demonstrates the general rule for all materials and represents the average value across an interval of temperature from zero (black) to infinity (green) that is the cold-pressure limitation (CPL).
The cold-pressure limit, which is used to determine the thickness of windows and lenses, is the maximum measured value of a material’s damping coefficient against the thermal gradient. This ratio is plotted as a function the temperature differential along the viewing angle for a given viewing angle and cte for the window or lens. The bending moment of a system is the change in angle of incidence from spherical or linear. 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 thought of as a function of the focal length divided by the duration of the curve (i.e. the interval between shots).
For a particular temperature range and a certain focal length of a window or lens assembly, the inside temperature of the system will always fall within the prescribed curve , in the perfect order known as a “curved surface.” For instance, the curve for the thermal conductance of a glass bead inside a glass vial that has holes in it could be plotted as a function of the focal length, 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 surface temperature of the system and the curve of variation for the particular window assembly must remain the same. Variable apertures can cause the curve to be curvilinear because of variations in the glass’s temperature used for creating the bead, ambient air temperature, length of the lens, and time of photography. A typical example of a curly surface can be seen in the signature left by a photographer of flowers.
A lens and window must be mounted so that their focal points and lines of sight are properly aligned. If the interior surface temperature of an object is too cold for the lens, the outside temperature of the frame and the interior temperature will be too high. The frame will not have to be adjusted to account for internal temperature variations or cooling effects. If there are no temperature differences from outside, then the system’s inside surface temperature will be the same for a particular focal length. If the system is located in an area that has restricted or unobstructed views of surrounding scenery or buildings it might be necessary to regulate internal temperatures.
The first mechanical interlocking system used to secure lenses onto cameras were constructed of plastic or other materials that would be able to bend or form in response to changes in mounting pressure. This design was later adopted for use with pinhole glasses. This kind of lens assembly has a problem with the mechanical joints that connect the lens and frame might break or become indented. If this happened then it is required to replace the entire assembly in a relatively short period of time. Due to this, this type of system has been replaced by more robust designs.
Pinhole glasses lenses are typically constructed with a frame made of metal and a thin, glass or plastic lid. At a minimum the lense designs should have a hermetically sealed lens construction. A hermetically sealed lens construction contains a sealed surface along the bottom and top of the lens assembly. The top surface could contain a mechanical seal similar to the one described above. It could also include an lip, adhesive, or layer of plastic film.
A lens surface that contains a substrate and adheres to the base is another illustration of this kind of lens and window assembly. This system usually consists of glass casings and series of lens compartments. The windows could also include other kinds of devices, like light emitters, or thermometers. This type of system could include a thermostat or light emitter which controls the temperature of the room. A variety of compartments could be used to house the temperature control and a variety of other devices such as an alarm clock, thermostat, or other devices.
This is not a full list of all kinds of lens and window assemblies that are available. It’s a good indication of the important technologies related to this invention. Please read the entire disclosure for more information. Particularly, you should read the portions relating to “details of the Present Invention” and “Description of the Process With Respect to the Identification of the Various classes of products involved in the Present Application.”
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