Because of the dependence of our thermal emission behavior upon the wavelength of the heat source due to the dependence of our thermal emission behavior on the wavelength, only a few wavelengths are suitable for thermal measurements. The following graphs show the range of thermal transmission for common windows and thermal lenses for infrared thermometers. The blue-colored curve represents the general rule for all materials. It is the average value across the temperature range from zero (black), infinity (green), and that is the cold-pressure limit, (CPL).
The cold-pressure limit, which is used for windows and lenses is the highest measured value of a material’s damping ratio against the thermal gradient. This ratio is calculated as a function of the temperature difference along the angle of view for given viewing angle and cte of a window or lens. The bending moment of a system is the variation in angle of incidence from spherical or linear. This makes the slope proportional to the curve. The focal length of an entire system is also an important factor in the slope. This 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 surface temperature of the system will always be within the prescribed curve for a particular temperature and the focal length of a window assembly or lens. This is also referred to as a “curved top”. The thermal conductance curve of a glass bead within a glass vial can be plotted as a function the focal length, the temperature difference between the bottom and the surface of the vial 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 should remain the same. If the aperture is adjustable and the curve is not fixed, then it could be curving as a result of the variation in the temperature of the glass used to create the bead as well as the temperature of the ambient atmospheric air on the inside surface of the vial and the focal length as well as the duration of shooting. A signature left by an artist on the petals of a flower is an example of a curving surface.
A lens and window must be mounted in a manner that their focal points and lines of sight are properly aligned. If the temperature of the inside of a 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 need to be adjusted in order to compensate for internal temperature fluctuations or cooling effects. If there are no temperature variations from outside, the system’s inside surface temperature will be the same for a particular focal length. However, if the camera is mounted at a location with an obstruction or restricted view of the nearby building or scenery the internal temperature may need to be controlled.
The first mechanical interlocking systems that were used to secure lenses onto cameras were made of plastic or other materials that could change shape or bend according to changes in mounting pressure. This innovation was later adopted to work with pinhole glasses. This type of lens assembly is not without a problem with the mechanical joints that connect the frame and lens could break or be indented. If this happens then it would be required to replace the entire assembly in a relatively short amount of time. Because of this, this type of system has been replaced by more robust designs.
Pinhole glasses lenses are usually constructed with a frame made of metal and a thin, glass or plastic lid. The lense designs should at the very minimum have a hermetically-sealed construction. A hermetically sealed lens construction contains a sealed surface along the top and bottom of the lens assembly. The top layer could be a part of a mechanical seal similar to that described above. It could also include an lip, adhesive, or layer of plastic film.
Another embodiment of this type of lens and window assembly is a lens surface that contains a substratethat is attached to the base of the window assembly. The system typically consists of a glass casing and a series lens compartments. Other types of devices could be integrated into the windows, like thermometers and light emitters. In certain instances, the device used to control the temperature of the room might also be part of this kind of system. In this case the system would comprise of compartments that could be used to house the temperature controller as well as a range of other devices, such as an alarm thermostat or clock.
This is not a complete listing of all the types of lens and window assemblies that are available. It’s a good indication of the most important technologies that are related to this invention. Please read the entire disclosure for more details. In particular, you should take a look at the sections relating 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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