Because of the dependence of our thermal emission behaviour on the thermal wavelength because of the dependence of our thermal emission on the wavelength, only certain wavelengths are suitable for thermal measurements. The following figures reveal the thermal transmission range of common thermal lenses and window substances for infrared thermometers. The blue-colored curve is the general rule that applies to all materials. It is the average of the temperature range of zero (black) to infinity (green) and that is the cold-pressure limit (CPL).
For windows and lenses the cold-pressure limit is defined as the maximum measured value of the damping ratio of a material in relation to 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 window or lens. The bending moment of a system is the variation in the angle of incidence, which is linear or spherical. This results in the slope being proportional to the curve. The focal length of an entire system is also an element in the slope. This can be considered as a function of the focal length divided the period of the curve (i.e. the duration between shots).
For a given temperature range and a given focal length of a window or lens assembly, the inside surface temperature of the system will always fall within the prescribed curve in the perfect order called a “curved surface.” For instance the curve for the thermal conductivity of a glass beads inside a glass vial that has holes in it could be plotted as a function of the focal length and the temperature difference within the vial between the bottom of the bead and the vial’s surface, and the angle of incidence for a particular window assembly. If the aperture is fixed for all shots, then the distance between the surface temperature of the system and the curve of variation for that particular window assembly should always remain constant. If the aperture is variable this means that the curve could be curved as a result of the variations in the temperature of the glass used in the making of the bead and the temperature of the ambient atmospheric air on the inside surface of the vial, and the focal length and time of shooting. A typical example of a curly surface can be seen in the signature of the photographer of the flower.
A window and lens must be mounted so that their focal points and lines of sight are properly aligned. If the inside surface temperature 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. When the outside temperature of the lens and the frame are equally, then the frame will not require any adjustment 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 particular focal length without the need for any other adjustments, provided no external source of temperature fluctuations affects the system. If the system is located in an area that has restricted or blocked views of surrounding structures or landscape it might be necessary to control the internal temperature.
The first mechanical interlocking systems used to secure lenses onto cameras were made of plastic or other materials that would bend or mold depending on changes in mounting pressure. This innovation was later adapted for use with pinhole glasses. A problem with this type of lens assembly is that the mechanical joints between the frame and lens may indent or break. If this should be happening, it will be essential for the entire system to be replaced within a short time. This is the reason why this system has been replaced with more robust designs.
Lenses made for use with pinhole glasses usually have a metallic frame and a thin glass or plastic lid. The lense designs should at a minimum have a hermetically sealed construction. A hermetically sealed lens construction has a sealed surface on the bottom and top of the lens assembly. The top surface may have a similar mechanical seal similar to that described above. It could also include an lip, adhesive or a layer of plastic film.
A lens surface that contains an adhesive and is bonded to the base is another embodiment of this type window and lens assembly. The system typically consists of glass casings and series lens compartments. The windows can also house different kinds of devices like light emitters, or thermometers. In some instances, the device used to control the temperature within the room could be part of this type of system. In this case, a series of compartments could house the temperature control together with a variety of other devices, like an alarm thermostat or clock.
This is not a complete list of all kinds of lens and window assemblies that are available. It’s an indication of the significant technologies that are connected to this invention. For more information, please look over the complete disclosure. Please refer to the sections on “details about the invention” and “Description of the process with Regard to the Identification of the Different Classes of Products That Are Involved In the Present Application.”
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