Due to the high dependence of our thermal emission behavior on the thermal wavelength 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 ranges of thermal transmission of common thermal lenses and window materials for infrared thermometers. The blue-colored curve is the general rule that applies to all materials. It is the average value across a temperature range of zero (black) to infinity (green), and that is the cold-pressure limit (CPL).
For windows and lenses The cold-pressure limit can be defined as the highest value of the damping ratio of a substance against the thermal gradient. This ratio is calculated as a function of the temperature difference across the angle of view for given viewing angle and the cte of a lens or window. The slope of this curve is proportional to the bending moment of an entire system, which is the result when the angle of incidence shifts from linear to spherical. The slope of this curve is also proportional to the focal length of a system, which can be described as a function of the focal length divided by the period 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 internal surface temperature of the system will always be within the prescribed curve , in an exact regularity, also known as a “curved surface.” The thermal conductance curve of a glass beads inside a glass vial could be plotted as a function of the focal length, the temperature difference between the bottom of the vial and its surface and the angle of incidence of a given window. If the aperture is fixed for all shots, then the area between the system’s surface temperature and the curve of variation will remain the same. If the aperture is variable, then the curve may be curved as a result of the variations in the temperature of the glass used to make the bead and the temperature of the ambient air that is on the inside surface of the vial, and the focal length and duration of shooting. A typical example of a curly surface can be seen in the signature left by the photographer of the flower.
Mounting a lens and window should be done so that their focal points, and lines of sight are correct. If the inside surface temperature of the system is too hot for the lens, then the outside surface temperature of the frame will be cooler and the inside temperature of the lens will be too warm. The frame won’t need to be adjusted to account for internal temperature variations or cooling effects. If there aren’t any temperature variations from outside, the frame’s internal temperature will be the same for the given focal length. If the system is located in an area that has limited or obstructed views of the surrounding scenery or buildings it could 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 be able to bend or form in response to changes in mounting pressure. This design was later adapted to pinhole glasses. A problem with this type of lens assembly is that the mechanical joints between the lens and frame may indent or break. In the event of this occurring, it would be necessary for the entire assembly to be replaced in a short time. This is why this system is being replaced with more robust designs.
Lenses that are designed to work with pinhole glasses typically have a metallic frame and a thin glass or plastic lid. These lense designs should at a minimum, have a hermetically sealed construction. A hermetically sealed lens construction has a sealed surface on the top and bottom of the lens assembly. The top surface could contain an elastomeric seal similar to the one described above. It could also contain another substance, for instance, an adhesive, a lip, or a layer of plastic film.
Another variation of lens and window assembly includes a lens surface that contains a substrate, which adheres to the base of the window assembly. The system typically consists of glass casings and series lens compartments. Other types of devices could be included in the windows, for example, thermometers and light emitters. In certain instances, the device used to control the temperature of the room might also be part of this type of system. A series of compartments could be used to house the temperature control as well as a variety of other devices, such as an alarm clock, thermostat, or other devices.
This isn’t a complete list of all kinds of window and lens assemblies that are available. However, it does provide an indication of the key technologies associated with this invention. Please refer to the complete disclosure for more information. In particular, you should look over the sections that pertain to “details of the present invention” and “Description of the Process With Respect to the Identification of the Different classes of products Involved in the Present Application.”
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