Due to the high dependence of our thermal emission behaviour on the wavelength of the heat source due to the extreme dependence of our thermal emission behavior on the wavelength, only certain wavelengths are suitable for measurements of thermal. The following graphs show the range of thermal transmission of standard 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 of the temperature range from zero (black) and infinity (green) and that is the cold-pressure limit (CPL).
For windows and lenses the cold-pressure limit is defined as the highest measured value of the damping ratio of a material in relation to the thermal gradient. This ratio is plotted as a function of the temperature differential along the viewing angle for a given viewing angle and cte for the lens or window. 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 focal length of a system is also a factor in the slope. It is thought of as a function of the focal length divided by the length of the curve (i.e. the duration between shots).
The inside temperature of the system will always remain within the prescribed curve for a particular temperature and the focal length of the window assembly or lens. This is also known as a “curved top”. For instance the curve of thermal conductance of a glass piece inside a glass vial that has holes in it could be plotted in relation to 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 area between the temperature of the inside surface of the system and the curve of variation for the particular window assembly must remain constant. Variable apertures can cause the curve to be curvilinear due to changes in the temperature of glass used to create the bead and ambient air temperature length of the lens, and time of photography. A good example of a curly surface can be seen in the signature left by a photographer of the flower.
A lens and window must be mounted in a way that their focal points and lines of sight are properly aligned. If the temperature of the inside of the system is too cold for the lens, the outside temperature of the frame and its interior temperature will be too high. The frame will not have to be adjusted in order to compensate for internal temperature fluctuations or cooling effects. If there are no temperature differences from outside, then the system’s inside surface temperature will be the same for a given focal length. If the system is located in an area with restricted or blocked views of the surrounding buildings or scenery it might be necessary to regulate the internal temperature.
The first mechanical interlocking systems used to attach lenses to cameras were made of plastic or other materials that would be able to bend or form according to changes in mounting pressure. This design was later adopted to work with pinhole glasses. The issue with this kind of lens assembly is that the mechanical joints between the lens and frame may indent or break. If this happened then it will be necessary to replace the entire unit in a relatively short period of time. Due to this, this type of system has been replaced by more robust designs.
Lenses that are designed for use with pinhole glasses usually have a metallic frame and an elongated glass or plastic lid. These lense designs must at a minimum, have a hermetically sealed construction. A hermetically sealed lens construction contains a sealed surface along the bottom and top of the lens assembly. The top surface may be sealed with a similar seal as the one mentioned earlier. It could also contain some other substance, such as an adhesive, lip, or a layer of plastic film.
Another variation of window and lens assembly includes a lens surface that contains a substrate, which adheres to the base of the window assembly. The system typically consists of a glass casing and a series of lens compartments. Other kinds of devices can be included in the windows, for example, light emitters and thermometers. This kind of system could include a thermostat or light emitter which controls the temperature in the room. In this case the system would comprise of compartments that could house the temperature control as well as a range of other devices, including an alarm clock or thermostat.
This isn’t a complete list of all the kinds of lens and window assemblies that are available. It is indicative of the most important technologies that are related to this invention. Please refer to the entire disclosure for more information. Refer to the sections relating to “details about the present invention” and “Description of the Method with Regard to the Identification of the various types of products which are involved in the Present Application.”
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