Low f-number refracting telescope with dynamic altitude compensation

Abstract

A system and method for a low f-number precision variable focus telescope, including a telescope housing that accommodates an optical system, are disclosed. The system includes a first temperature sensing device for detecting the temperature of the telescope housing, a second temperature sensing device for detecting the ambient temperature around the telescope housing, and a pressure sensing device for detecting the ambient pressure around the telescope housing. A controller operably communicates with the first temperature sensing device, the second temperature sensing device, and the pressure sensing device. The controller adjusts heaters to maintain the telescope housing at a desired temperature in response to signals from the first temperature sensing device, the second temperature sensing device, and the pressure sensing device to achieve diffraction-limited performance.

Description

Technical Field

[0001]

[0001] This disclosure generally relates to refractive telescopes.

Background Art

[0002]

[0002] Conventional telescopes rely on using multiple lenses to achieve the desired magnification and clarity. However, temperature variations can cause these lenses or the housings holding the lenses to expand or contract, resulting in a change in the focal length of the telescope and thereby degrading the image quality. Athermalization is the process of designing an optical system to minimize the effects of temperature changes on the performance of the optical system.

[0003]

[0003] Refractive telescopes can be designed to be athermal (i.e., not temperature-sensitive) by carefully selecting the optical glass and telescope housing materials such that the temperature-dependent properties cancel each other out as the temperature of the telescope changes. These properties include the temperature change of the refractive index (dn / dT) and the coefficient of thermal expansion (CTE) of the housing and lens materials.

[0004]

[0004] The "f-number" (sometimes called the F-number or f#) is the ratio of the focal length to the aperture diameter. Here, a "low" f-number is considered to be an f-number of 2 or less. Designing small telescopes with low f-numbers can be difficult for athermalization techniques because they can be very sensitive to lot-to-lot variations in the material properties of the refractive index (i.e., dn / dT) and the coefficient of thermal expansion (i.e., CTE). This variation may require the evaluation of the material properties of all lots during manufacturing.

[0005]

[0005] One way to reduce the sensitivity of a refracting telescope to ambient temperature is through the addition of a heater, which reduces the temperature range of the telescope by keeping it at a high temperature or at least warm (about 50°C) at all times when exposed to ambient temperature. In other words, in the current circumstances of the art, refracting telescopes with low f-numbers may be heated or maintained at about 50°C so that they are maintained as a constant but high temperature. The use of a heater maintains the telescope at this static temperature.

[0006]

[0006] Low f-number refracting telescopes are also sensitive to ambient air pressure and altitude because the refractive index of air varies from approximately n=1.0003 at sea level to approaching n=1 for high-altitude and space vacuum applications. This complicates ground testing and operation due to the difference in focal length between the ground and the system's operating altitude.

[0007]

[0007] Current methods to compensate for these effects include attempting to athermalize the telescope by balancing the dn / dT and CTE of the glass and housing materials. To do this for low f-number refracting telescopes, designers often need to match a complex and expensive set of optics and housing material properties and shapes. This is easier to match for high f-number (i.e., f-number greater than 2) telescopes, but that match comes at the cost of making the telescope larger and heavier (i.e., increasing size, weight, power, and cost considerations). Furthermore, they use housing materials with matched CTEs, which have glass or lens materials, and these are typically heavy and have poor thermal conductivity (e.g., Invar, titanium) or are expensive (e.g., beryllium alloy). In addition, they may include mechanical movement (e.g., piezoflexure or motor-driven) focusing techniques to adjust the spacing between lenses, which are complex, bulky, and heavy. [Overview of the project]

[0008]

[0008] Conventional systems or telescopes that would use a heater to maintain the telescope at a constant high temperature have the drawbacks discussed above. For example, even when heated, the body or housing of the telescope may not be at a single uniform temperature due to a thermal gradient from the front to the rear of the telescope, and temperature sensitivity still exists. Given the shortcomings of the current state of the art for variable-focus refractors, particularly low-f-number refractors, there remains a need for a variable-focus refractor optimized for temperature sensitivity for heating compensation of altitude shift. This disclosure addresses this need, among many others, and provides a low-f-number refractor with dynamic altitude compensation by taking into account ambient air altitude (or pressure) and, optionally, ambient air temperature.

[0009]

[0009] According to an illustrative aspect of the embodiments of the present disclosure, a pre-existing or legacy heater on an afocal telescope may be utilized in conjunction with an improved system architecture or computer program product that reoptimizes the entire design to take advantage of the fact that the heater is present. This illustrative system of the present disclosure utilizes software to control the heater to maintain the temperature at a desired operating temperature. This allows the system of the present disclosure to use a software controller that knows the ambient pressure and altitude (from sea level to space) and the ambient ambient temperature. Altitude / pressure and temperature are used to calculate what temperature the telescope should be maintained at to compensate for the telescope temperature and altitude / pressure. In addition to dynamically controlling the temperature of the telescope housing, embodiments of the present disclosure utilize the telescope housing of the present disclosure which includes a material having an increased coefficient of thermal expansion. It should be recalled that previous designs of afocal telescopes have used housing materials such as titanium to equilibrate changes in the optical behavior of the glass. However, titanium has a coefficient of thermal expansion that is fairly close to that of the glass that forms the triplet pair optics. To dynamically control temperature by software to adjust the focus of a telescope over a desired temperature range, the system of the present disclosure can provide greater control over the focus with respect to temperature. In other words, the amount of focus for all degrees of temperature shift can be controlled. To achieve this, the present disclosure utilizes certain materials having a higher coefficient of thermal expansion than the previous use of titanium. One such material that would suffice is aluminum. This higher CTE provides the ability to change the focus more precisely with respect to a given temperature change than was previously possible with a titanium housing. In other words, by heating or controlling the temperature of the housing, the physical housing expands and contracts, changing the distance between the first pair of optics and the second pair of triplet optics.

[0010]

[0010] Embodiments disclosed herein will achieve diffraction-limited performance (≤ ±1 / 4 wave focus shift) over a wide range of temperature and altitude environments by compensating for high sensitivity to ambient pressure by incorporating at least some or all of the following features: a housing material (e.g., aluminum) having a high coefficient of thermal expansion (CTE) for high focus sensitivity to temperature, resulting in a wide dynamic range of focus shift compensation; a housing material (e.g., aluminum) having high thermal conductivity, resulting in a low thermal gradient when heater power is applied, enabling accurate temperature measurement and resulting in a low gradient in which parts of the telescope are exposed to different ambient temperatures; and wide A pair of triplet lenses with low intrinsic sensitivity to temperature (i.e., three lenses defining a first set of lenses from the pair, and three lenses defining a second set of lenses from the pair) that result in maintaining higher-order optical aberrations (out-of-focus) under control over a temperature range; a telescope temperature sensor used to monitor the temperature of the telescope body for closed-loop control of heater power; an ambient pressure sensor used as feedback for telescope temperature setpoint control to compensate for focus shifts from sea level to over 100 kft (i.e., space); and an ambient temperature sensor used as feedback for telescope setpoint control for ambient temperature-related corrections.

[0011]

[0011] Some embodiments of the present disclosure enable the provision of a 5x magnification afocal SWIR telescope with a compact 50mm aperture. Some of these embodiments provide a faster thermal response than conventional systems, which enables the systems of the present disclosure to achieve full performance over a greater temperature and altitude operating envelope. Some embodiments provide rapid dynamic focusing, which enables: a significantly extended performance operating envelope (altitude and temperature) for the system, a significant reduction in the testing and calibration time required at supply bases and factories, cost and schedule improvements, improved yield by reducing the tight dependence on custom precision housing dimensions with a matched set of optics, and elimination of time constraints on system operation over a telescope warm-up period, which speeds up the field factory testing and operating timeline.

[0012]

[0012] In an illustrative embodiment, an embodiment of the present disclosure may provide a method comprising: sensing the temperature of a telescope housing with a first temperature sensing device, wherein the telescope housing comprises an internal and external, the internal of the telescope housing housing optical elements, the optical elements in the telescope housing are associated with an F-number, the F-number being 2 or less; sensing ambient pressure around the telescope housing with a pressure sensing device; and adjusting a heater directly or indirectly coupled to the telescope housing in response to signals from the first temperature sensing device and the pressure sensing device to achieve diffraction-limited performance of the optical elements with a controller operably communicating with the first temperature sensing device and the pressure sensing device.

[0013]

[0013] In another illustrative aspect, embodiments of the present disclosure may provide a low f-number precision varifocal telescope comprising a telescope housing having an internal and external, wherein the internal part of the telescope housing houses optical elements, the optical elements in the telescope housing are associated with an f-number, the f-number being 2 or less, a heater directly or indirectly coupled to the telescope housing, a first temperature sensing device for detecting the temperature of the telescope housing, a pressure sensing device for detecting ambient pressure around the telescope housing, and a controller operably communicating with the first temperature sensing device and the pressure sensing device, the controller adjusting the heater to maintain the telescope housing at a desired temperature in order to achieve diffraction-limited performance in response to signals from the first temperature sensing device and the pressure sensing device.

[0014]

[0014] Sample embodiments of the present disclosure are described in the following description, shown in the drawings, and specifically and clearly indicated and described in the appended claims. [Brief explanation of the drawing]

[0015] [Figure 1]

[0015] Figure 1 is an illustrative side elevation view of an exemplary low-f-number telescope according to one embodiment of the present disclosure. [Figure 2]

[0016] Figure 2 is a longitudinal cross-sectional view of an illustrative low-f-number telescope along line 2-2 in Figure 1. [Figure 3]

[0017] Figure 3 is an illustrative schematic chart illustrating an exemplary low-f-number telescope according to one embodiment of the present disclosure. [Figure 4]

[0018] Figure 4 is a flowchart illustrating an illustrative method or process according to one embodiment of the present disclosure. [Figure 5]

[0019] Figure 5 is a graph illustrating the difference in focal shift versus lens F-number at various altitudes. [Figure 6A]

[0020] Figure 6A is a graph illustrating the performance of the telescope of this disclosure and conventional telescopes over time along an illustrative flight path. [Figure 6B]

[0021] Figure 6B is a graph illustrating altitude versus pressure for the exemplary flight path shown in Figure 6A. [Modes for carrying out the invention]

[0016]

[0022] Similar numbers refer to the same parts throughout the entire drawing.

[0017]

[0023] Figures 1 and 2 illustrate telescopes having an f-number of 2 or less. Thus, as used herein, the term “low f-number” refers to an optical system or assembly having an f-number less than 2. In one embodiment, the low f-number telescope is a variable focus telescope 10. The telescope 10 includes a housing 12 and one or more optical lenses 14. In one embodiment, the optical lenses 14 include a pair of triplet lenses 14A, 14B. As an example, the telescope housing 12 may be made of aluminum. The material selected to form the housing 12 of the telescope 10 should also have high thermal conductivity. Thus, aluminum may be a desirable material to use when constructing the housing 12 because it has a high level of thermal conductivity and a high CTE. A high level of thermal conductivity reduces the possibility of a thermal gradient across the body of the housing 12 of the telescope 10.

[0018]

[0024] The heat spreader 16 is attached to or coupled to the telescope housing 12 either directly or indirectly. In one embodiment, the heat spreader 16 surrounds at least a portion of the telescope housing 12. Additionally, the heat spreader 16 may connect to the periphery of the telescope housing 12. In one embodiment, the heat spreader 16 may be a single unit. In another embodiment, the heat spreader 16 may be machined into at least two parts. The parts of the heat spreader 16 may be connected or coupled by any suitable method, including but not limited to screws, adhesives, and welds. For example, the heat spreader 16 may be made of aluminum.

[0019]

[0025] In one embodiment, the heat spreader 16 is wrapped around the outside of the central barrel of the housing 12 of the telescope 10. In one embodiment, the heat spreader 16 may be a foil-based heater (including heater 18 or heater element) conforming to the outer surface of the central barrel of the housing between the pair of triplet optics 14A and 14B. Considering the distribution of heat, if the material has a low level of thermal conductivity, the central portion of the telescope will be warmer, and the outer end where the triplet optics are located will be colder. Thus, forming the housing 12 from a material with high thermal conductivity results in a low gradient that establishes temperature uniformity throughout the body forming the telescope, while allowing the heater to be utilized only in the central portion of the telescope. Another material useful for forming a telescope housing with relatively high CTE and relatively high thermal conductivity would be copper.

[0020]

[0026] In one embodiment, at least one heater 18 is attached to the heat spreader 16 to adjust the temperature of the precision variable focus telescope 10. The heater 18 can be distributed in a pattern such as stripes or rows along the section of the heat spreader 16 to enable effective heating. In one embodiment, the heater 18 is an electrical resistance heater connected to the heat spreader 16 via a foil or film. The electrical resistance heater 18 has a resistance element for uniformly heating the heat spreader 16. By way of example, the electrical resistance heater 18 can be made of polyimide foil. In one embodiment, the electrical resistance heater 18 is attached to the heat spreader 16 by a pressure-sensitive adhesive. The composition of the adhesive should not impede the heating of the heat spreader 16. Other attachment mechanisms for the film heater 18 to the heat spreader 16 include screws, pins, and posts. In another embodiment, the heat spreader 16 can be eliminated, and the heater 18 can be simply connected to or wound around the housing 12 of the telescope 10. For example, as described in more detail herein, when the housing 12 of the telescope 10 is manufactured with a sufficiently high CTE and a sufficiently high thermal conductivity, the heat spreader can be eliminated, and the heater 18 can be directly connected to or wound in direct contact with the housing 12 of the telescope.

[0021]

[0027] FIG. 2 illustrates a cross-sectional view of a low f-number precision variable focus telescope 10 having a telescope housing 12 and optics 14. In one embodiment, a gap pad can be sandwiched between the telescope housing 12 and the heat spreader 16. The gap pad fills the empty space between the heat spreader 16 and the telescope housing 12 to uniformly heat the telescope housing 12. In various embodiments, the gap pad can be connected to the telescope housing 12 and the heat spreader 16. By way of example, the gap pad can be made of a material having a low thermal impedance to transfer heat from the heat spreader 16 to the telescope housing 12.

[0022]

[0028] Figures 1 to 3 illustrate that at least one temperature sensing device 20 is attached to or coupled to the heat spreader 16 either directly or indirectly. The device 20 can be regarded as the first temperature sensing device 20. The temperature sensing device 20 can also be installed at other locations on the telescope. The temperature sensing device 20 measures the temperature of the telescope 10. As an example, the temperature sensing device 20 can include a thermistor. In one example, the temperature sensing device 20 is located away from the heater 18. In another example, there are multiple temperature sensing devices 20. According to one embodiment, a temperature calibration table can be used. For example, the temperature of the telescope 10 or any of its locations is established by knowing the temperature at the temperature sensing device 20.

[0023]

[0029] The first temperature sensing device 20 is operably coupled to the heater (see also FIG. 3). The first temperature sensing device 20 has an output that is processed to control the heater. Software, protocol, instructions, or other logic communicates operably with the temperature sensor to maintain the telescope 10 at a desired temperature. One particular temperature useful for maintaining the telescope within the desired operating temperature range would be within plus or minus 5% of 50 degrees Celsius. The software controls the amount of electrical power provided to the heater to adjust the desired temperature. The control of the heater power is accomplished through closed-loop control. Closed-loop control refers to the temperature sensor on the telescope that measures the temperature of the telescope. That temperature or data is provided to a PID control loop (proportional integral derivative control loop) that generates feedback to adjust the heater power to the heater on the telescope to always maintain the temperature sensor at the desired setpoint. Thus, the loop between the temperature sensor and the heater power is closed.

[0024]

[0030] The system or telescope 10 also includes a second temperature sensing device 22 for measuring the ambient temperature of a volume of air or space adjacent to and near the outside of the telescope 10. In one embodiment, the second temperature sensing device 22 consists of a single sensor. In another specific embodiment, the system of the present disclosure utilizes sensors as part of the second temperature sensing device 22 to detect ambient temperature near the telescope. Specifically, this embodiment may utilize three separate ambient temperature sensors that collectively define the second temperature sensing device 22, the first ambient temperature sensor detecting ambient temperature near the front end of the telescope 10, the middle ambient temperature sensor detecting ambient temperature near the center of the telescope 10, and the third ambient temperature sensor detecting ambient temperature near the second end of the telescope 10. The ambient temperature sensors that collectively define the second temperature sensing device 22 detect ambient temperature to identify three different temperature zones around the telescope 10. The ambient temperatures can be averaged over their respective values, or they can be used independently in the process of controlling the heater 18, as discussed herein.

[0025]

[0031] The pressure sensor 24 is adjacent to the telescope 10 and measures the ambient pressure of the volume of air or space near the outside of the telescope 10. The pressure sensor 24 may, as an alternative, be an altimeter, insofar as the pressure is nearly directly related to altitude.

[0026]

[0032] Figure 3 illustrates an illustrative embodiment of the precision variable focus telescope heating mechanism control loop 30. A first temperature sensing device 20, mounted on the heat spreader 16 or another part of the housing 12 of the telescope 10, measures the temperature of the telescope 10. A second temperature sensing device 22 is adjacent to the telescope 10 and measures the ambient temperature of the volume of air or space near the outside of the telescope 10. A pressure sensor 24 is adjacent to the telescope 10 and measures the ambient pressure of the volume of air or space near the outside of the telescope 10.

[0027]

[0033] The temperature feedback 32 from the first temperature sensing device 20 is an input to a temperature digitizing electronic device that converts the temperature feedback or signal into a read value that can be processed. The temperature feedback 32 is sent to the summing block 34.

[0028]

[0034] The temperature feedback 36 from the second temperature sensing device 22 is an input to a temperature digitizing electronic device that converts the temperature feedback 36 or the signal into a read value that can be processed. The temperature feedback 36 is sent to a temperature setpoint algorithm or temperature setpoint logic 38.

[0029]

[0035] Ambient pressure feedback 40 from the pressure sensing device 24 is an input to a temperature digitizing electronic device that converts the pressure feedback or signal into a read value that can be processed. The pressure feedback 40 is sent to a temperature setpoint algorithm or temperature setpoint logic 38.

[0030]

[0036] The temperature setpoint logic 38 determines the temperature at which the telescope 10 or telescope housing 12 should operate in order to optimize diffraction-limited performance (≤ ±1 / 4 wave focus shift) across a wide range of temperature and altitude environments. This allows the telescope 10, which has a low f-number, to compensate for high sensitivity to ambient pressure and ambient temperature.

[0031]

[0037] With respect to the setpoint logic 38, one illustrative embodiment has only an ambient temperature input (from the second temperature sensing device 22), while another embodiment has both an ambient pressure input (from the pressure device 24) and an ambient temperature sensor input. Thus, in some embodiments, the ambient pressure sensor input is optional to the setpoint logic 38. In some embodiments, the ambient temperature sensor input is optional to the setpoint logic 38 to use only ambient pressure. Furthermore, other embodiments allow the setpoint logic 38 to use multiple pressure and temperature sensor inputs when there is a large gradient around the telescope. For example, if the ambient temperature around each end of the telescope is different, it may be advantageous to have readings for both zones to calculate the optimal setpoint temperature for the focal point of the telescope 10. The setpoint logic 38 may include a lookup table for determining the best setpoint temperature for the focal point of the telescope based on ambient pressure and temperature readings. The setpoint logic may use the lookup table to perform a method for determining the best setpoint temperature for the focal point of the telescope based on ambient pressure and temperature readings. The setpoint logic 38 can interpolate between points in the lookup table. The setpoints in the lookup table temperature setpoints can be determined by performing calibration tests over ambient temperature and pressure of the telescope or a representative telescope while measuring the telescope's focus.

[0032]

[0038] In an alternative configuration, instead of a lookup table, the setpoint logic 38 may utilize an equation used with coefficients similarly determined by formally fitting calibration test data. For example, “Setpoint temperature = A*(ambient temperature) + B*(ambient pressure) + C”, where the equation and A, B, and C are coefficients determined by the telescope design. The values ​​of A, B, and C would be based on the best fit of the equation to the calibration data.

[0033]

[0039] The output 42 of the setpoint logic 38, which is the desired telescope temperature, is sent to the adder block 34. The adder block 34 receives the output 42 of the setpoint logic 38 as an input to the adder block 34. The adder block 34 also receives temperature feedback 32 from the first temperature sensing device 20 as an input to the adder block 34.

[0034]

[0040] The output of the summing block 34 is an input to a telescope temperature input controller or controller 44. The controller 44 may be coupled to a sample rate count, which outputs readings from both temperature sensors 20 and 22 as 12-bit telescope temperatures, respectively. The 12-bit telescope temperatures may be an input to a 1-a filter unit to apply filter gain. The filtered telescope temperatures may be an input to a heater controller 44. In one example, the controller 44 is a proportional / integral controller (PID controller) implemented within a controller such as a field-programmable gate array (FPGA). In one embodiment, a temperature calibration table is used to provide a more precise temperature for the telescope 10.

[0035]

[0041] The output of the PID controller 44 supplies the heater input to a switching power supply. For example, the switching power supply may be a "buck," "boost," "buckboost," "isolated," or "non-isolated" switching power supply. This switching power supply adjusts the voltage across the heater 18, which may be an electric film heater that applies thermal energy to the heat spreader 16, thereby maintaining the telescope 10 at a desired temperature to achieve diffraction-limited performance. In one embodiment, the temperature setpoint for the control loop 30 is "user-configurable" through a digital interface.

[0036]

[0042] In another example, the output of the PID controller 44 supplies the heater input to a linear power supply for the heater 18. This linear power supply adjusts the voltage across the heater 18, which may be an electric film heater, thereby controlling the power applied by the electric film heater and maintaining the telescope 10 at a desired temperature to achieve diffraction-limited performance.

[0037]

[0043] Figure 3 illustrates the heater power to the heater 18 surrounding the telescope 10. There is another temperature sensor (telescope central housing) that detects the temperature at its center. This temperature sensor (i.e., device 20) measures what the temperature at the center of the telescope is at a given time. Its temperature signal is sent to an adder block. In the adder block, the data from the central temperature sensor is added to the setpoint temperature at which the system wants to maintain the telescope. The adder block generates an error signal if the measured temperature is not equal to the setpoint temperature. In other words, if the temperature sensor data is equal to the setpoint temperature, there is no error output from the adder block. When an error signal is present, it enters a PID control loop, which is a proportional controller. The proportional controller generates a signal to the heater to tell it how much power is needed to heat the telescope to the desired setpoint temperature. This process loops and repeats until there are no more error signals. For example, if the setpoint temperature falls below a registered temperature detected by a temperature sensor located in the center of the housing, the PID controller will send a command to turn off power to the telescope to cool it down. Alternatively, if the temperature detected by the intermediate temperature housing falls below the setpoint temperature, the PID controller will increase power to the heater to warm the telescope. This is a feedback loop where the process is continuous, continuously warming or cooling the telescope to maintain it at the desired setpoint temperature.

[0038]

[0044] The system of this disclosure is an improvement over conventional telescopes that use stationary or fixed temperatures to maintain the telescope at a preset temperature. These earlier systems or devices lacked a feedback loop that allowed for responsive changes to be made to the heater based on the telescope's temperature or altitude. This was limiting, as it only allowed the telescope to be focused within a specific range of altitudes. By adding the feedback loop and PID controller of this disclosure, systems utilizing telescopes with this improved technique enable the use of a wider range of altitudes and temperatures, while simultaneously maintaining the usability of low f-number telescopes at those wider ranges of altitudes and pressures. The setpoint calculator also acquires pressure data from a pressure sensor and calculates the pressure as a function of temperature or in relation to temperature. By measuring pressure along with temperature, the setpoint calculator can determine the best focus for the telescope considering temperature and pressure parameters. This can be calculated via a lookup table or pre-calibrated measurements, or alternatively, adaptively learned through artificial intelligence.

[0039]

[0045] It should be noted that the control loop can take many different forms, and the PID of the controller 44 disclosed herein is not required in all embodiments of the controller 44. However, the PID has been shown to be reliable and efficient for the purposes disclosed herein. Thus, while the PID may be part of the control loop, it is not required as long as the control loop still dynamically powers the heater elements around or on the telescope, taking temperature and pressure into account, in order to maintain the telescope's focus shift within the desired target range.

[0040]

[0046] Figure 4 illustrates a method for focusing the optical system in a low f-number precision variable focus telescope according to one embodiment, which is generally shown in 400. This method 400 in this example includes designing the optical design specifications to obtain linear performance, which is generally shown in 402. The method also includes adjusting the coarse adjustment of the telescope optical system to the desired focus during assembly by aligning and separating lenses, which is generally shown in 404. The method further comprises using a heater circuit over a specified temperature and altitude range to characterize the optimal telescope temperature for the best focus, which is generally shown in 406. The method may further comprise adjusting the heater driver setpoint temperature for fine adjustment of the telescope optical system focus, which is generally shown in 408. The method includes maintaining the heater driver setpoint temperature for diffraction-limited performance over a wide temperature and altitude (from sea level to outer space) environment, which is generally shown in 410.

[0041]

[0047] In one embodiment, initial (coarse) adjustment of the desired focus utilizes a conventional method of adjusting and setting the lens optics within the telescope housing 12 while the telescope is heated to an initial value. This method further includes adjusting the heater driver setpoint temperature for fine adjustment of the telescope optics, which is generally shown in 406. In one embodiment, fine (precise) adjustment of the focus is achieved by correcting the temperature of the telescope until diffraction-limited performance is achieved. Precise adjustment of the focus, correcting the temperature of the telescope to diffraction-limited performance, is achieved by using feedback 32 from a first temperature sensing device 20, feedback 36 from a second ambient temperature sensing device 22, and optionally feedback 40 from an ambient pressure sensing device 24. In various embodiments, the temperature range used for adjusting the focus is greater than the maximum ambient temperature of the air surrounding the telescope 10. A constant heat flow to the telescope 10 eliminates the need to use cooling to maintain the temperature.

[0042]

[0048] In one embodiment, the telescope 10 of the present disclosure is an afocal telescope in which a collimated beam enters a first end of the telescope at a first pair of triplet lenses that focus the light to a focal point. From the focal point, the light spreads to a second pair of triplet lenses. The light then passes through the second pair of triplet lenses and exits from the second end of the afocal telescope as a collimated beam of a smaller diameter. The focal length is considerably shorter compared to the diameter of the optical lenses. This results in a low F-number.

[0043]

[0049] As illustrated in Figure 5, as the f-number decreases for a given telescope, the telescope becomes more sensitive to the refractive index of the air or medium. Figure 5 plots the difference in focus between sea level and the f-number of a lens for examples at different altitudes. Line 50A represents the difference in focus between sea level and a conventional telescope located in space or at very high altitudes (>100,000 feet). Line 50D represents the difference in focus from sea level for a conventional telescope located at 10,000 feet. Lines 50B and 50C represent two intermediate altitudes located between sea level and outer space. As shown by lines 50A–50D, even at low altitudes, the difference in focus is high (i.e., above the known limiting threshold of 0.25) for lenses with low f-numbers. The graph in Figure 5 also shows that the 0.25 limit in focus (shown by dashed line 52) is a generally accepted rule of thumb for a sharp focus. As shown below in Figure 6A, the telescope 10 of this disclosure is capable of achieving an operation below a focus shift limit of 0.25 (wherein a range of + / - 0.25 is shown as the focus shift range 62) based on the structural configuration detailed in Figures 1-3 and the operation detailed in Figures 3-4.

[0044]

[0050] Figures 6A and 6B are graphs showing focus shift calculations based on the telescope 10 utilizing the second temperature sensing device 22 and pressure sensing device 24. The focus shift calculation models the residual focus shift of the system. Figure 6B illustrates the flight profile of a platform (which may be manned or unmanned) whose altitude changes over time. For example, as altitude increases, pressure decreases. For example, at time zero, altitude is at its lowest point and pressure is at its highest point. As altitude increases over time, pressure decreases.

[0045]

[0051] Figure 6A identifies the calculated amount of focus shift of the telescope 10 when the temperature inside the telescope is controlled using both the first temperature sensing device 20, the second temperature sensing device 22, and the pressure sensing device 24. Figure 6A illustrates that the target focus shift pv wave should be within the focus shift range 62, which is + / -0.25 wave. From the results graphed in Figure 6A, the dynamic feedback loop controlled temperature system for the telescope 10 yields better results in maintaining the telescope within the target focus shift range 62 than the previous static system. For example, at time zero, the heater 18 is not yet turned on, and all systems are relatively out of focus. However, as time increases, the dynamic feedback loop controlled temperature system for the telescope 10 quickly brings the telescope 10 within the target focus shift range by heating the telescope, as evidenced by line 60B which is located within range 62. Then, as the heater 18 heats the telescope 10, the telescope 10 can be focused more effectively. In older systems or conventional telescopes where temperature was a static value, the telescope's focused value never existed when the platform carrying the system was on the ground. This is illustrated by line 60A of an older static telescope, which is horizontal at a point of approximately 1.25 on the vertical focus shift scale.

[0046]

[0052] Line 60B shows that, based on ambient temperature and pressure being sent to the controller 44, the temperature on the telescope 10 is set to its desired temperature before the platform leaves the ground. As shown in this illustrative graph, the platform carrying the telescope takes off or begins its flight path in approximately 45 minutes. The temperature of the telescope 10 is constantly changing, as sensed by the first and second temperature sensing devices 20, 22 and the pressure sensing device 24. However, the dynamically controlled system, as demonstrated by line 60B, allows the telescope 10 to be maintained and remain within the target focus shift band range 62 throughout the entire flight pattern. This is shown in distinction from the old static system represented by line 60A, which may move out of the target focus shift range when altitude and pressure change. For example, with respect to the old static design, at time T120, the platform begins to decrease its altitude, which in turn increases its pressure. The old design deviates from the target focus shift range 62 or band between approximately time T135 and approximately time T195 (where time is represented by a capital T preceding time on the X axis of the graph in Figures 6A-6B). However, over this same time frame from T135 to T195, the new system of the telescope 10 is able to maintain the focus shift within the target band range 62 as the altitude and pressure of the flight path change, as demonstrated by line 60B within the range 62 from time T135 to time T195.

[0047]

[0053] While this disclosure has described in one embodiment that the telescope housing 12 is formed from aluminum, other embodiments may use different materials to form the housing 12. However, these other embodiments should select a material with a sufficiently high CTE value. For example, as previously stated, titanium with a CTE value of about 9 was determined to be too low for the desired purpose of a low f-number (i.e., f-number of 2 or less) precision variable focus telescope. Therefore, other materials to be used to form the telescope housing 12 should have a CTE value greater than 9. In another embodiment, copper with a CTE value of about 16 was determined to be sufficient to improve the performance of the titanium housing. Therefore, other materials that may be used to form the telescope housing 12 should have a CTE value greater than 16. Some illustrative other materials with a CTE value greater than 9 that may be used to form the housing 12 according to other embodiments of this disclosure are identified below in Table 1.

[0048] [Table 1-1] [Table 1-2] [Table 1-3] [Table 1-4] [Table 1-5]

[0049]

[0054] In addition to the sufficiently high CTE values ​​discussed above, the materials used for the housing 12 should also have sufficiently high thermal conductivity values. For example, as previously stated, titanium, with a thermal conductivity value of about 22.4 W / mK at 0°C, was deemed too low for the desired purpose of a low F-number (i.e., F-number of 2 or less) precision variable focus telescope. Therefore, other materials to be used to form the telescope housing 12 should have a thermal conductivity value greater than that of titanium. In another embodiment, copper, with a thermal conductivity value of about 401 W / mK at 0°C, was deemed sufficient to improve the performance of the titanium housing. Therefore, other materials that can be used to form the telescope housing 12 should have a thermal conductivity value greater than about 100. Several exemplary other materials with a thermal conductivity value greater than about 100 that can be used to form the housing 12 according to other embodiments of this disclosure are identified below in Table 2.

[0050] [Table 2-1] [Table 2-2] [Table 2-3] [Table 2-4] [Table 2-5] [Table 2-6]

[0051]

[0055] Although sensing devices 20, 22, and 24 have been described in detail herein, the telescope 10 or its associated system or assembly may additionally include one or more other sensors for sensing or collecting data relating to the surrounding environment or the operation of the device, assembly, or system. Some illustrative sensors that can be electronically coupled to the devices, assemblies, or systems of the Disclosure (either directly connected to or remotely connected to the devices, assemblies, or systems of the Disclosure) may include, but are not limited to, accelerometers that sense acceleration experienced during rotation, translation, velocity / speed, moved location, and elevation gained; gyroscopes that sense movement during angular orientation and / or rotation, as well as rotation; altimeters that sense atmospheric pressure, elevation changes, climbed terrain, local pressure changes, and immersion in liquid; impellers that measure the amount of fluid passing through them; global positioning sensors that sense location, elevation, distance traveled, and velocity / speed; audio sensors that sense local ambient sound levels or voice detection; photo / light sensors that sense ambient light intensity, ambient, day / night, and UV exposure; TV / IR sensors that sense light wavelengths; other temperature sensors that sense machine or motor temperature, ambient air temperature, and ambient temperature; and moisture sensors that sense ambient moisture levels.

[0052]

[0056] The devices, assemblies, or systems of this disclosure may include wireless communication logic coupled to sensors on the device, assembly, or system. The sensors collect data and provide it to the wireless communication logic. The wireless communication logic may then transmit the data collected from the sensors to a remote device. Thus, the wireless communication logic may be part of a broader communication system in which one or more devices, assemblies, or systems of this disclosure can be networked together to report alerts and, more generally, to be remotely accessed and controlled. Depending on the type of transceiver installed in the device, assembly, or system of this disclosure, the system may use a variety of protocols for communication (e.g., Wi-Fi, ZigBee, MiWi, Bluetooth®). For example, each of the devices, assemblies, or systems of this disclosure may have its own IP address and may communicate directly with a router or gateway. This would typically occur if the communication protocol is Wi-Fi.

[0053]

[0057] In another example, a point-to-point communication protocol such as MiWi or ZigBee is used. One or more of the devices, assemblies, or systems of the disclosure may act as repeaters, or the devices, assemblies, or systems of the disclosure may be connected together in a mesh network to relay signals from one device, assembly, or system to the next. However, the individual devices, assemblies, or systems in this scheme will typically not have their own IP addresses. Instead, one or more of the devices, assemblies, or systems of the disclosure will communicate with a repeater that has an IP address, or another type of address, identifier, or authentication information, required to communicate with an external network. The repeater will communicate with a router or gateway.

[0054]

[0058] In any communication method, the router or gateway communicates with a communication network such as the Internet, but in some embodiments, the communication network may be a private network that uses the Transmission Control Protocol / Internet Protocol (TCP / IP) and other common Internet protocols, but does not interface with the broader Internet, or only selectively interfaces through a firewall.

[0055]

[0059] The system for receiving and processing signals from the devices, assemblies, or systems of this disclosure may vary from embodiment to embodiment. In one embodiment, alerts and signals from the devices, assemblies, or systems of this disclosure may be sent via email or a simple message service (SMS; text message) gateway, and thus they may be sent as email or SMS text messages to a remote device such as a smartphone, laptop, or tablet computer, which is monitored by a responsible individual, group of individuals, or department such as a maintenance department. Thus, if a particular device, assembly, or system of this disclosure generates an alert for data points collected by one or more sensors, that alert may be sent directly to the individual responsible for repairing it, in email or SMS format. Of course, email and SMS are just two examples of possible communication methods, and different forms of communication may be used in other embodiments.

[0056]

[0060] The system also allows individuals to access the devices, assemblies, or systems of the disclosure for configuration and diagnostic purposes. In this case, individual processors or microcontrollers of the devices, assemblies, or systems of the disclosure may be configured to function as web servers, providing an online interface that can be used to configure the devices, assemblies, or systems using a protocol such as the Hypertext Transfer Protocol (HTTP). In some embodiments, the system may be used to configure several devices, assemblies, or systems of the disclosure at once. For example, if several devices, assemblies, or systems are of the same model and located in similar locations within the same location, it may not be necessary to configure the devices, assemblies, or systems individually. Instead, an individual may provide configuration information, including baseline operating parameters, for several devices, assemblies, or systems at once.

[0057]

[0061] As described herein, aspects of the present disclosure may include one or more electrical, pneumatic, hydraulic, or other similar secondary components and / or systems. The present disclosure is therefore intended and understood to include any necessary operating components. For example, an electrical component will be understood to include any suitable and necessary wiring, fuses, or the like for its normal operation. Any connections between various components not expressly described herein may be made through any suitable means, including mechanical fasteners or more permanent mounting means such as welding or the like. Alternatively, where feasible and / or desirable, the various components of the present disclosure may be formed integrally as a single unit.

[0058]

[0062] Various inventive concepts can be embodied in one or more methods, and examples are provided. The operations performed as part of the method can be ordered in any suitable manner. Thus, although they are shown as sequential operations in the exemplary embodiments, embodiments can be constructed in which the operations are performed in a different order than those exemplified, which may include performing several operations simultaneously.

[0059]

[0063] While various embodiments of the invention have been described and illustrated herein, those skilled in the art will readily conceive of a variety of other means and / or structures for performing the functions and / or obtaining one or more of the results and / or benefits described herein, and each of such variations and / or modifications will be considered to fall within the scope of the embodiments of the invention described herein. More generally, those skilled in the art will readily recognize that all parameters, dimensions, materials and configurations described herein are intended to be illustrative, and that actual parameters, dimensions, materials and / or configurations will depend on one or more specific uses in which the teachings of the invention are used. Those skilled in the art will be able to recognize many equivalents to a particular embodiment of the invention described herein, or to verify this by simply using routine experimentation. Accordingly, it should be understood that the embodiments described herein are presented only as examples, and within the scope of the appended claims and their equivalents, embodiments of the invention may be carried out in ways other than those specifically described and claimed. Embodiments of the invention in this disclosure cover each individual feature, system, article, material, kit and / or method described herein. In addition, any combination of two or more such features, systems, articles, materials, kits, and / or methods is included within the scope of the inventions of this disclosure, provided that such features, systems, articles, materials, kits, and / or methods are not mutually inconsistent.

[0060]

[0064] The embodiments described above can be implemented in any of a number of ways. For example, embodiments of the technology disclosed herein can be implemented using hardware, firmware, software, or a combination thereof. When implemented in software, the software code or instructions can be executed on any suitable processor or set of processors, whether provided to a single computer or distributed across multiple computers. Furthermore, the instructions or software code can be stored in at least one non-temporary computer-readable storage medium.

[0061]

[0065] Furthermore, a computer or smartphone that can be used to execute software code or instructions via its processor may have one or more input and output devices. These devices may, among other things, be used to present a user interface. Examples of output devices that may be used to provide a user interface include a printer or display screen for visual presentation of output and a speaker or other sound-generating device for audible presentation of output. Examples of input devices that may be used for a user interface include a keyboard, as well as pointing devices such as a mouse, touchpad, and digitizing tablet. As another example, a computer may receive input information through speech recognition or in other audible formats.

[0062]

[0066] Such computers or smartphones may be interconnected by one or more networks of any suitable form, including local area networks or wide area networks such as corporate networks, and intelligent networks (INs), or the Internet. Such networks may be based on any suitable technology, operate according to any suitable protocol, and may include wireless networks, wired networks, or fiber optic networks.

[0063]

[0067] The various methods or processes outlined herein may be coded as software / instructions executable on one or more processors using any one of a variety of operating systems or platforms. Additionally, such software may be written using any of several suitable programming languages ​​and / or programming or scripting tools, and may be compiled as executable machine code or intermediate code that runs on a framework or virtual machine.

[0064]

[0068] In this regard, various invention concepts may be embodied as computer-readable storage media (or multiple computer-readable storage media) (e.g., computer memory, one or more floppy disks, compact disks, optical disks, magnetic tapes, flash memory, USB flash drives, SD cards, field-programmable gate arrays or circuit configurations in other semiconductor devices, or other non-temporary or tangible computer storage media) encoded with one or more programs that, when executed on one or more computers or other processors, perform methods for implementing the various embodiments of the present disclosure discussed above. One or more computer-readable media may be portable such that one or more programs stored thereon can be loaded onto one or more different computers or other processors to implement the various embodiments of the present disclosure discussed above.

[0065]

[0069] The terms “program,” “software,” or “instructions” are used herein in a general sense to refer to any type of computer code or set of computer executable instructions that may be used to program a computer or other processor to implement various aspects of the embodiments discussed above. In addition, it should be recognized that, according to one aspect, one or more computer programs that, when executed, perform the methods of the Disclosure do not need to reside on a single computer or processor, but can be modularly distributed among several different computers or processors to implement various aspects of the Disclosure.

[0066]

[0070] Computer executable instructions can take many forms, such as program modules, which are executed by one or more computers or other devices. Generally, a program module includes routines, programs, objects, components, data structures, etc., that perform a specific task or implement a specific abstract data type. Typically, the functions of a program module can be combined or distributed as desired in various embodiments. Thus, one aspect or embodiment of the present disclosure may be a computer program product comprising at least one non-temporary computer-readable storage medium operably communicating with a processor, the storage medium storing instructions that, when executed by the processor, implement the methods or processes described herein, the instructions comprising steps for performing the methods or processes described herein.

[0067]

[0071] Furthermore, data structures can be stored in a computer-readable medium in any suitable format. For simplicity of illustration, a data structure may be shown as having fields associated through locations within the data structure. Such relationships can also be achieved by allocating locations in the computer-readable medium that convey the relationships between fields to storage for the fields. However, any suitable mechanism can be used to establish relationships between information in the fields of a data structure, including through the use of pointers, tags, or other mechanisms that establish relationships between data elements.

[0068]

[0072] It should be understood that all definitions defined and used herein take precedence over dictionary definitions, definitions in literature referenced by reference, and / or the ordinary meanings of the terms defined.

[0069]

[0073] As used herein, “logic” includes, but is not limited to, hardware, firmware, software, and / or combinations thereof for performing functions or actions and / or for triggering functions or actions from other logic, methods, and / or systems. For example, depending on the desired application or need, logic may include software-controlled microprocessors, discrete logic such as processors (e.g., microprocessors), application-specific integrated circuits (ASICs), programmed logic devices, memory devices containing instructions, electrical devices with memory, or similar. Logic may include one or more gates, combinations of gates, or other circuit components. Logic can also be fully embodied as software. Where multiple logics are described, it may be possible to combine multiple logics into a single physical logic. Similarly, where a single logic is described, it may be possible to distribute that single logic across multiple physical logics.

[0070]

[0074] Furthermore, the logic(s) presented herein to accomplish various methods of this system may be intended to improve existing computer-centric or internet-centric technologies that may not have prior analog versions. The logic(s) may provide specific functions directly related to structures that address and solve some of the problems identified herein. The logic(s) may also provide significantly more advantages to solving these problems by providing illustrative inventive concepts as specific logical structures and harmonized functions of methods and systems. Furthermore, the logic(s) may also provide specific computer implementation rules that improve existing technical processes. The logic(s) provided herein extend beyond simply collecting data, analyzing information, and displaying results. Furthermore, parts or all of this disclosure may rely on underlying equations derived from specific arrangements of equipment or components as described herein. Thus, parts of this disclosure that relate to specific arrangements of components do not cover abstract concepts. Furthermore, this disclosure and the accompanying claims present teachings that go beyond the performance of previously known, well understood, routine, and conventional activities in the art. In some of the methods or processes of this disclosure that may incorporate several aspects of natural phenomena, the steps of the process or method are novel and useful additional features.

[0071]

[0075] The articles "a" and "an," when used herein in the specification and claims, should be understood to mean "at least one" unless the opposite is explicitly stated. The phrase "and / or," when used herein in the specification and claims (if present), should be understood to mean "either or both" of the elements thus combined, that is, elements that exist conjunct in some cases and disjunct in others. Multiple elements enumerated by "and / or" should be interpreted similarly, that is, "one or more" of the elements thus combined. Other elements other than those specifically identified by the "and / or" clause may exist at their discretion, whether related to or unrelated to those specifically identified elements. Thus, as a non-restrictive example, a reference to "A and / or B," when used in conjunction with unrestrictive language such as "equipped with," may in one embodiment refer to A only (including elements other than B at their discretion), in another embodiment to B only (including elements other than A at their discretion), in yet another embodiment to both A and B (including other elements at their discretion), and so on. Where used herein in the specification and claims, “or” should be understood to have the same meaning as “and / or” as defined above. For example, when separating items in a list, “or” or “and / or” should be interpreted as inclusive, that is, including at least one of several elements or a list of elements, but also including more than one, and optionally including additional unlisted items. Only terms that clearly indicate the opposite, such as “only one of” or “exactly one of” or, as used in claims, “consisting of,” would refer to including exactly one element of several elements or a list of elements.In general, the term “or” as used herein should be interpreted only as indicating an exclusive substitution (i.e., “one or the other, but not both”) when preceded by terms of exclusivity such as “either of,” “one of,” “only one of,” or “exactly one of.” “Consisting essentially of” should, when used in patent claims, have its usual meaning as it is used in the field of patent law.

[0072]

[0076] When used herein in the specification and claims, the phrase “at least one” refers to a list of one or more elements and means at least one element selected from any one or more elements in the list of elements, but not necessarily including at least one of all elements specifically enumerated in the list of elements, nor excluding any combination of elements in the list of elements. This definition also allows for the presence of elements other than those specifically identified in the list of elements to which the phrase “at least one” refers, whether related to or unrelated to those specifically identified elements, at the discretion of the party. Therefore, as a non-restrictive example, "at least one of A and B" (or equivalently, "at least one of A or B," or equivalently, "at least one of A and / or B") may, in one embodiment, refer to A which optionally includes more than one (and optionally includes elements other than B) in which B is absent; in another embodiment, refer to B which optionally includes more than one (and optionally includes elements other than A) in which A is absent; and in yet another embodiment, refer to A which optionally includes more than one, and B which optionally includes more than one (and optionally includes other elements), and so on.

[0073]

[0077] Although the components of this disclosure are described herein in relation to one another, if claimed or used individually, one of the components disclosed herein may constitute the subject matter of the invention. In accordance with the above example, if the disclosed embodiments teach the features of components A and B, the subject matter of the invention may be a combination of A and B, A alone, or B alone, unless otherwise stated herein.

[0074]

[0078] As used herein in the specification and claims, the term “effecting” or any phrase or claim element beginning with the term “effecting” should be understood to mean causing something to occur or bring something to happen. For example, causing an event may be caused by an action of the first party, even though the second party actually performs the event or causes the event to occur to the second party. In other words, “effecting” means that one party provides another party with the tools, objects, or resources necessary to cause an event to occur. Thus, in this example, the claim element “cause an event to occur” means that the first party provides the second party with the tools or resources necessary for the second party to perform the event, but the single positive action is the responsibility of the first party to provide the tools or resources to cause the event to occur.

[0075]

[0079] When a feature or element is referred to herein as being "on" another feature or element, it may be directly present on the other feature or element, or there may be intervening features and / or elements. In contrast, when a feature or element is referred to as being "directly on" another feature or element, there are no intervening features or elements. When a feature or element is referred to as being "connected," "attached," or "coupled" to another feature or element, it will also be understood that it may be directly connected, attached, or coupled to the other feature or element, or there may be intervening features or elements. In contrast, when a feature or element is referred to as being "directly connected," "directly attached," or "directly coupled" to another feature or element, there are no intervening features or elements. Features and elements described or shown in reference to one embodiment may apply to other embodiments. It will also be recognized by those skilled in the art that a reference to a structure or feature positioned "adjacent" to another feature may have a portion that overlaps with or lies beneath the adjacent feature.

[0076]

[0080] Spatially relative terms such as “under,” “below,” “lower,” “over,” “upper,” “above,” “behind,” “in front of,” and similar terms may be used herein to facilitate descriptions of the relationship between one element or feature and another element or feature, as illustrated in the figures. It will be understood that spatially relative terms are intended to encompass different orientations of a device in use or operation, in addition to the orientation illustrated in the figures. For example, if the device in the figure is inverted, an element described as “under” or “beneath” another element or feature will be oriented “over” the other element or feature. Thus, the illustrative term “under” can encompass both up and down orientations. The device may be oriented in other ways (rotated 90 degrees or to other orientations), and the spatially relative descriptive terms used herein will be interpreted accordingly. Similarly, terms such as “upwardly,” “downwardly,” “vertical,” “horizontal,” “lateral,” “transverse,” “longitudinal,” and similar terms are used herein for illustrative purposes only, unless otherwise indicated.

[0077]

[0081] The terms “first” and “second” may be used herein to describe various features / elements, but these features / elements should not be limited by these terms unless otherwise indicated in the context. These terms may be used to distinguish one feature / element from another. Thus, without departing from the teachings of the invention, the first feature / element discussed herein may be referred to as the second feature / element, and similarly, the second feature / element discussed herein may be referred to as the first feature / element.

[0078]

[0082] The embodiments are implementations or examples of the present disclosure. References to “embodiments,” “one embodiment,” “several embodiments,” “one particular embodiment,” “explanatory embodiment,” or “other embodiments,” or similar terms in this specification, mean that certain features, structures, or characteristics described in relation to the embodiments are included in at least some embodiments of the present invention, but not necessarily in all embodiments. Various appearances of “embodiments,” “one embodiment,” “several embodiments,” “one particular embodiment,” “explanatory embodiment,” or “other embodiments,” or similar terms do not necessarily refer to the same form.

[0079]

[0083] Where this specification states that a component, feature, structure, or characteristic may be included ("may," "might," or "could"), that particular component, feature, structure, or characteristic is not required to be included. Where this specification or the claims refer to an "a" or "an" element, it does not mean that there is only one of that element. Where this specification or the claims refer to an "additional" element, it does not exclude the existence of more than one additional element.

[0080]

[0084] Where used herein in the specification and claims, including as used in examples, and unless otherwise specified, all numbers may be read as if preceded by the words “about” or “approximately,” even if the terms do not explicitly appear. The phrases “about” or “approximately” may be used when describing magnitude and / or location to indicate that the described value and / or location is within a reasonable expected range of the value and / or location. For example, a number may have values ​​such as + / -0.1% of the stated value (or range of value), + / -1% of the stated value (or range of value), + / -2% of the stated value (or range of value), + / -5% of the stated value (or range of value), + / -10% of the stated value (or range of value), etc. Any numerical range described herein is intended to include all subranges contained therein.

[0081]

[0085] In addition, the methods for carrying out this disclosure may occur in sequences different from those described herein. Therefore, unless otherwise specified, the sequences of the methods should not be read as limiting. It is recognizable that similar results can be achieved by performing some of the steps of the methods in a different order.

[0082]

[0086] In the claims and the above specification, all transitional phrases such as “comprising,” “including,” “carrying,” “having,” “containing,” “involving,” “holding,” “composed of,” and similar phrases should be understood to mean unrestricted, i.e., including but not limited to. Only the transitional phrases “consist of” and “essentially consist of” are considered closed or semi-closed transitional phrases, respectively, as described in the U.S. Patent and Trademark Office's Patent Examination Procedure Manual.

[0083]

[0087] To the extent that this disclosure uses the term “invention” in any title or section thereof, this term is included as required by the formatting requirements for Word document submissions in accordance with the U.S. Patent and Trademark Office guidelines / requirements, and should not be considered in any form as a denial of any subject matter.

[0084]

[0088] In the above explanation, certain terms are used for the sake of brevity, clarity, and understanding. Since such terms are used for explanatory purposes and are intended to be interpreted broadly, they should not imply any unnecessary limitations beyond the requirements of prior art.

[0085]

[0089] Furthermore, the descriptions and examples of the various embodiments of this disclosure are illustrative, and this disclosure is not limited to the very details shown or described.

Claims

1. A low f-number precision variable focus telescope, A telescope housing comprising an interior and an exterior, wherein the interior of the telescope housing houses an optical element, and the optical element in the telescope housing is associated with an F-number, and the F-number is 2 or less. A heater directly or indirectly coupled to the telescope housing, A first temperature sensing device for detecting the temperature of the telescope housing, A pressure sensing device for detecting pressure in the vicinity of the telescope housing, A controller that is operably communicating with the first temperature sensing device and the pressure sensing device. A low f-number precision variable focus telescope comprising, wherein the controller adjusts the heater to maintain the telescope housing at a desired temperature in response to signals from the first temperature sensing device and the pressure sensing device in order to maintain diffraction-limited performance.

2. The low f-number precision variable focus telescope according to claim 1, further comprising a second temperature sensing device for detecting the temperature adjacent to the telescope housing, wherein the controller operably communicates with the first temperature sensing device, the second temperature sensing device, and the pressure sensing device, and the controller adjusts the heater to maintain the telescope housing at a desired temperature in response to signals from the first temperature sensing device, the second temperature sensing device, and the pressure sensing device to achieve diffraction-limited performance.

3. The system further comprises an adder that is operably communicating with the first temperature sensing device, the second temperature sensing device, and the pressure sensing device, and a linear power supply having inputs and outputs. The adding device communicates with the controller in an operable manner. The controller includes a proportional / integral controller (PID controller) with inputs and outputs, The low f-number precision variable focus telescope according to claim 2, wherein the input of the linear power supply receives an output signal from the PID controller, and the linear power supply adjusts the voltage across the heater and controls the power applied to the heater to maintain the telescope housing at the desired temperature.

4. The present invention further comprises a heat spreader having a first side and a second side, the second side of the heat spreader being coupled to at least a portion of the exterior of the telescope housing, The low f-number precision variable focus telescope according to claim 1, wherein the heater is directly coupled to the heat spreader.

5. The low f-number precision variable focus telescope according to claim 4, further comprising a gap pad disposed between the exterior of the telescope housing and the heat spreader.

6. The low f-number precision variable focus telescope according to claim 1, wherein the telescope housing is made of a material having a coefficient of thermal expansion (CTE) value greater than 9.

7. The low f-number precision variable focus telescope according to claim 6, wherein the CTE value is greater than 16.

8. The low f-number precision variable focus telescope according to claim 1, wherein the telescope housing comprises aluminum.

9. The low F-number precision variable focus telescope according to claim 1, wherein the telescope housing is made of a material having a thermal conductivity value greater than 100 W / mK at 0°C.

10. The low f-number precision variable focus telescope according to claim 1, wherein the heater is an electric heater comprising polyimide foil.

11. A first temperature sensing device senses the temperature of the telescope housing, wherein the telescope housing comprises an internal and external section, the internal section of the telescope housing houses an optical element, the optical element in the telescope housing is associated with an F-number, and the F-number is 2 or less. The pressure sensing device senses the pressure in the vicinity of the telescope housing, A controller that is operably communicating with the first temperature sensing device and the pressure sensing device adjusts a heater directly or indirectly coupled to the telescope housing in response to signals from the first temperature sensing device and the pressure sensing device in order to maintain the diffraction-limited performance of the optical element. A method that includes [a certain feature].

12. The second temperature sensing device senses the temperature adjacent to the telescope housing, and the controller is operationally communicating with the first temperature sensing device, the second temperature sensing device, and the pressure sensing device. In order to achieve diffraction-limited performance in response to signals from the first temperature sensing device, the second temperature sensing device, and the pressure sensing device, the heater is adjusted to maintain the telescope housing at a desired temperature. The method according to claim 11, further comprising:

13. The adding device adds the signals from the first temperature sensing device, the second temperature sensing device, and the pressure sensing device, and the adding device is operablely communicating with the controller. The output from the adding device is transmitted to the controller, wherein the controller includes a proportional / integral controller (PID controller) having inputs and outputs. The output from the PID controller is received into a linear power supply having inputs and outputs, The voltage across the heater is adjusted via the linear power supply to control the power applied to the heater so as to maintain the telescope housing at the desired temperature. The method according to claim 12, further comprising:

14. Observing the optical design specifications of the telescope in order to obtain the linear performance of the telescope, Adjusting the coarse adjustment of the telescope to the desired focus, To fine-tune the aforementioned telescope, the setpoint temperature is adjusted, The temperature of the telescope is corrected until diffraction-limited performance is achieved, and this temperature correction is accomplished by using feedback from the first temperature sensing device and feedback from the second temperature sensing device. The method according to claim 11, further comprising:

15. The method according to claim 14, wherein the temperature correction is further achieved by using feedback from an ambient pressure sensing device.

16. A computer program product comprising at least one non-temporary computer-readable storage medium, wherein the non-temporary computer-readable storage medium is operablely communicating with a computer processing unit (CPU) in an optical system on a mobile platform. The optical system comprises a housing, a first temperature sensing device for sensing the temperature of the housing, a second temperature sensing device for sensing the ambient temperature around the housing, a pressure sensing device for sensing the ambient pressure around the housing, and a heater directly or indirectly coupled to the housing. The non-temporary computer-readable storage medium stores instructions that, when the instructions are executed by the CPU, perform a process to maintain the housing at a desired temperature in order to achieve diffraction-limited performance in response to signals from the first temperature sensing device, the second temperature sensing device, and the pressure sensing device, The temperature of the housing is determined by the first temperature sensing device, The second temperature sensing device determines the temperature adjacent to the housing, The pressure sensing device determines the pressure adjacent to the housing, Maintaining the temperature of the housing at the desired temperature in response to feedback from the first temperature sensing device, the second temperature sensing device, and the pressure sensing device. A computer program product that includes the following features.

17. The aforementioned instruction is, The adding device adds the signals from the first temperature sensing device, the second temperature sensing device, and the pressure sensing device, and the adding device communicates with the controller in an operable manner. The output from the adding device is transmitted to the controller, wherein the controller includes a proportional / integral controller (PID controller) having inputs and outputs. The output from the PID controller is received into a linear power supply having inputs and outputs, The voltage across the heater is adjusted to control the power applied to the heater via the linear power supply in order to maintain the housing at the desired temperature. The computer program product according to claim 16, further comprising the above.

18. The aforementioned instruction is, Observing the optical design specifications of the telescope in order to obtain the linear performance of the telescope, Adjusting the coarse adjustment of the telescope to the desired focus, To fine-tune the aforementioned telescope, the setpoint temperature is adjusted, The temperature of the telescope is corrected until diffraction-limited performance is achieved, and this temperature correction is accomplished by using feedback from the first temperature sensing device and feedback from the second temperature sensing device. The computer program product according to claim 17, further comprising the above.

Images