Low F-number refractive telescope with dynamic height compensation

Abstract

The invention discloses a system and a method for a low F-number precision focusable telescope. The low F-number precision focusable telescope comprises a telescope housing containing an optical system. The first temperature sensing device is used for detecting the temperature of the telescope shell, and the second temperature sensing device is used for detecting the ambient temperature around the telescope shell; the pressure sensing device is used for detecting environment pressure around the telescope shell. A controller is in operational communication with the first temperature sensing device, the second temperature sensing device, and the pressure sensing device. A controller adjusts the heater in response to signals from the first temperature sensing device, the second temperature sensing device, and the pressure sensing device to maintain the telescope at a desired temperature to achieve diffraction limit performance.

Description

TECHNICAL FIELD

[0001] The present invention relates generally to refractive telescopes. BACKGROUND

[0002] Conventional telescopes rely on multiple lenses to achieve the desired magnification and clarity. However, temperature changes can cause these lenses or the barrel that houses the lenses to expand or contract, thereby changing the focal length of the telescope and degrading the imaging quality. Athermalization is the process of optimizing the optical system design to minimize the effects of temperature changes on its performance.

[0003] By carefully selecting the optical glass and telescope housing materials, a refractive telescope design can be made athermal (i.e., insensitive to temperature) such that its temperature-dependent properties cancel each other out when the temperature of the telescope changes. These properties include the rate of change of refractive index with temperature (dn / dT) and the coefficient of thermal expansion (CTE) of the housing and lens materials.

[0004] The "f-number" (sometimes also referred to as F-number or f#) is the ratio of focal length to aperture. Here, a "low" f-number refers to a f-number less than or equal to 2. Athermalization techniques are extremely challenging for compact telescope designs with low f-numbers because they are very sensitive to differences in the rate of change of refractive index with temperature (i.e., dn / dT) and the coefficient of thermal expansion (i.e., CTE) of different batches of materials. This difference can result in the need to characterize each batch of materials during production.

[0005] To overcome the sensitivity of a refractive telescope to ambient temperature, one approach is to add a heater. The heater can keep the telescope at a high temperature or at least warm (about 50°C) at all times when exposed to ambient temperature, thereby reducing the range of temperature changes of the telescope. In other words, a low f-number refractive telescope can be kept at a constant temperature (albeit a higher temperature) by heating or keeping it at about 50°C, given the current state of the art. The use of a heater is key to maintaining the telescope at this constant temperature.

[0006] Low f-number refractive telescopes are very sensitive to ambient air pressure and altitude (elevation) because the index of refraction of air changes: about n = 1.0003 at sea level, and approaches n = 1 at high altitudes and in space vacuum applications. This makes ground testing and operation complicated due to the focusing differences between the ground and the operating altitude of the system.

[0007] Current methods of compensating for these effects include attempts to non-thermalize the telescope by balancing the dn / dT and CTE effects of the glass and enclosure materials. For low F-number refractive telescopes, to achieve this, designers often need to match the material properties and geometry of the optical elements and enclosure, which is both complex and expensive. For high F-number (i.e., f-number greater than 2) telescopes, matching these parameters is relatively easy, but at the cost of larger telescope size and mass (i.e., increased size, weight, power, and cost). In addition, they also use enclosure materials that match the CTE of the glass or lens material, which are often heavy and poor thermal conductors (e.g., Invar, titanium), or expensive (e.g., beryllium alloys). Additionally, they can employ mechanical motion (e.g., piezoelectric flexure or motor driven) focusing techniques to adjust the spacing between the lenses, which are complex structures that take up space and weight. SUMMARY

[0008] Systems or telescopes that use heaters to maintain a constant temperature of the telescope have the above-mentioned drawbacks. For example, even after heating, the temperature of the telescope body or enclosure can still not be uniform due to a temperature gradient from front to back inside the telescope body or enclosure, and thus temperature sensitivity can still exist. In view of the limitations of current refractive variable-focus telescopes, especially low F-number refractive telescopes, there is still a need for a refractive variable-focus telescope that is optimized for temperature sensitivity, thereby compensating for the focal length shift due to altitude changes. The present disclosure addresses this need and provides a low F-number refractive variable-focus telescope that achieves dynamic altitude compensation by taking into account the ambient air altitude (or air pressure) and optionally the ambient air temperature.

[0009] According to one exemplary aspect of embodiments of the present disclosure, the existing or conventional heater on a catadioptric telescope can be used in conjunction with the improved system architecture or computer program product, thereby re-optimizing the overall design to take advantage of the heater's presence. Exemplary systems of the present disclosure utilize software to control the heater to maintain the temperature at the desired operating temperature. This enables 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 temperature. The altitude / pressure and temperature are used to calculate the temperature that the telescope should maintain to compensate for changes in these temperatures and altitudes / pressures. In addition to dynamically controlling the temperature of the telescope housing, embodiments of the present disclosure also use a telescope housing that includes a material with a higher coefficient of thermal expansion. Looking back at previous catadioptric telescope designs, the housing material (e.g., titanium) was used to balance the changes in the optical performance of the glass. However, the coefficient of thermal expansion of titanium is very close to that of the glass that forms the three-piece optical elements. In order to dynamically control the temperature by software to adjust the focal length of the telescope within a desired temperature range, the system of the present disclosure is able to more precisely control the change in focal length with temperature. In other words, the amount of change in focal length for each degree change in temperature can be controlled. To accomplish this, the present disclosure employs a particular material that has a higher coefficient of thermal expansion than the titanium previously used. Aluminum is one suitable material. This higher coefficient of thermal expansion enables a more precise change in focal length for a given change in temperature than when a titanium housing was used. In other words, by heating or controlling the temperature of the housing, the physical housing expands and contracts, thereby changing the spacing between the first set of optical elements and the second set of three-piece optical elements.

[0010] Embodiments disclosed herein are to achieve diffraction-limited performance (≤ ± 1 / 4 wavelength defocus) over a wide temperature and altitude environment, compensating for high sensitivity to ambient pressure by incorporating at least some or all of the following features: a housing material with a high coefficient of thermal expansion (CTE) to achieve high focal sensitivity to temperature to obtain a wide dynamic range of defocus compensation (e.g., aluminum); a housing material with high thermal conductivity to produce a low thermal gradient when heater power is applied to enable precise temperature measurement and maintain a low gradient when certain parts of the telescope are exposed to different ambient temperatures (e.g., aluminum); a pair of three-piece lenses (i.e., three lenses make up a first set of lenses in a pair and three lenses make up a second set of lenses in a pair) that are less sensitive to temperature to control high-order optical aberrations (defocus) over a wide temperature range; the use of a telescope temperature sensor to monitor the temperature of the telescope body to enable closed-loop control of heater power; an ambient pressure sensor used as feedback for the telescope temperature setpoint control to compensate for defocus from sea level to > 100k feet or higher (i.e., space); and an ambient temperature sensor used as feedback for the telescope setpoint control to make corrections related to ambient temperature.

[0011] Some embodiments of this disclosure provide a compact 50mm aperture, 5x magnification, unfocused shortwave infrared telescope. Compared to existing systems, these embodiments offer a faster thermal response, enabling the system of this disclosure to achieve optimal performance over a wider operating range of temperature and altitude. Some embodiments provide rapid dynamic focus adjustment, thereby: significantly extending the system's performance operating range (altitude and temperature); significantly reducing the testing time and calibration required by suppliers and factories, thus reducing costs and shortening lead times; improving yield by reducing the stringent dependence on custom precision housing dimensions and matching optics; and eliminating the limitation on system operating time during telescope warm-up, thereby accelerating factory testing and field operation.

[0012] In one exemplary aspect, embodiments of this disclosure may provide a method comprising: sensing the temperature of a telescope housing using a first temperature sensing device, wherein the telescope housing includes an interior and an exterior, wherein the interior of the telescope housing includes optical elements, wherein the optical elements in the telescope housing are associated with an F-number, and wherein the F-number is less than or equal to 2; sensing the ambient pressure surrounding the telescope housing using a pressure sensing device; and adjusting a heater directly or indirectly coupled to the telescope housing using a controller that is operationally in communication with the first temperature sensing device and the pressure sensing device, thereby achieving diffraction-limited performance of the optical elements in response to signals from the first temperature sensing device and the pressure sensing device.

[0013] In another exemplary aspect, one embodiment of this disclosure may provide a low F-number precision focusable telescope comprising: a telescope housing including an interior and an exterior, wherein the interior of the telescope housing includes optical elements, wherein the optical elements in the telescope housing are associated with an F-number, and wherein the F-number is less than or equal to 2; 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 the ambient pressure surrounding the telescope housing; and a controller in operational communication with the first temperature sensing device and the pressure sensing device; wherein the controller adjusts the heater in response to signals from the first temperature sensing device and the pressure sensing device, thereby maintaining the telescope at a desired temperature to achieve diffraction-limited performance. Attached Figure Description

[0014] The following description sets forth exemplary embodiments of the present disclosure, which are illustrated in the accompanying drawings and are particularly pointed out and set forth in the appended claims.

[0015] Figure 1 This is a side view of an exemplary low F-number telescope according to one embodiment of the present disclosure.

[0016] Figure 2 It is along Figure 1 A longitudinal cross-sectional view of an exemplary low F-number telescope, taken from line 2-2 in the image.

[0017] Figure 3 This is an exemplary schematic diagram of an exemplary low F-number telescope according to one embodiment of the present disclosure.

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

[0019] Figure 5 It is a graph depicting the relationship between defocus difference and lens F-number at different heights.

[0020] Figure 6A It is a graph depicting the defocusing performance of the telescope of this disclosure and conventional telescopes along an exemplary flight path over time.

[0021] Figure 6B yes Figure 6A The graph shows the relationship between altitude and pressure for an exemplary flight path.

[0022] The same reference numerals in the accompanying drawings indicate the same parts. Detailed Implementation

[0023] Figure 1 and Figure 2 The image shows a telescope with an f-number of 2 or less. Therefore, in this document, "low f-number" refers to an optical system or component with an f-number less than 2. In one embodiment, a low f-number telescope is a focusing telescope 10. Telescope 10 includes a housing 12 and one or more optical lenses 14. In one embodiment, the optical lenses 14 include a pair of three-element lenses 14A and 14B. For example, the telescope housing 12 may be made of aluminum. The material used to manufacture the housing 12 of the telescope 10 should also have high thermal conductivity. Therefore, aluminum may be an ideal material for manufacturing the housing 12 because it has high thermal conductivity and a high coefficient of thermal expansion (CTE). High thermal conductivity reduces the likelihood of thermal gradients occurring inside the housing 12 of the telescope 10.

[0024] The heat sink 16 is directly or indirectly connected to or coupled to the telescope housing 12. In one embodiment, the heat sink 16 surrounds at least a portion of the telescope housing 12. Furthermore, the heat sink 16 may be connected to the periphery of the telescope housing 12. In one embodiment, the heat sink 16 may be a single-piece structure. In another embodiment, the heat sink 16 may be manufactured as at least two parts. The various parts of the heat sink 16 may be connected or coupled by any suitable method, including but not limited to screws, adhesives, and welding. For example, the heat sink 16 may be made of aluminum.

[0025] In one embodiment, a heat sink 16 surrounds the outer side of the central cylinder of the housing 12 of the telescope 16. In one embodiment, the heat sink 16 may be a foil-based heater (including heater 18 or a heating element) that is attached to the outer surface of the central cylinder of the housing, located between a pair of three-element optical elements 14A and 14B. Considering the location of heat, if the material has a low thermal conductivity, the central portion of the telescope will be hotter, while the outer end where the three-element optical elements are located will be cooler. Therefore, using a material with high thermal conductivity to make the housing 12 can reduce the temperature gradient, thereby achieving temperature uniformity throughout the entire body forming the telescope, while allowing the heater to be implemented only in the central portion. Another suitable material for manufacturing the telescope housing is copper, which has a relatively high coefficient of thermal expansion and relatively high thermal conductivity.

[0026] In one embodiment, at least one heater 18 is connected to the heat sink 16 to regulate the temperature of the precision focusable telescope 10. The heaters 18 may be distributed along various portions of the heat sink 16 and arranged in a pattern such as strips or rows to achieve effective heating. In one embodiment, the heater 18 is a resistance heater connected to the heat sink 16 via a foil or film. The resistance heater 18 has a resistive element for uniformly heating the heat sink 16. For example, the resistance heater 18 may be constructed from a polyimide foil. In one embodiment, the resistance heater 18 is connected to the heat sink 16 via a pressure-sensitive adhesive. The composition of this adhesive should not interfere with the heating of the heat sink 16. Other methods of connecting the film heater 18 to the heat sink 16 include screws, pins, and posts. In another embodiment, the heat sink 16 may be omitted, and the heater 18 may be directly connected to or wound around the housing 12 of the telescope 10. For example, when the housing 12 of the telescope 10 has a sufficiently high CTE and sufficiently high thermal conductivity (as described in more detail herein), the heat sink may be omitted, and the heater 18 may be directly connected to or wound around the housing 12 of the telescope in direct contact with it.

[0027] Figure 2 The diagram shows a cross-sectional view of a low f-number precision focusing telescope 10, which includes a telescope housing 12 and optics 14. In one embodiment, a spacer may be sandwiched between the telescope housing 12 and a heat sink 16. This spacer fills the gap between the heat sink 16 and the telescope housing 12, thereby uniformly heating the telescope housing 10. In various embodiments, the spacer may be connected to both the telescope housing 10 and the heat sink 16. For example, the spacer may be made of a low thermal resistance material, thereby transferring heat from the heat sink 16 to the telescope housing 10.

[0028] Figures 1-3At least one temperature sensing device 20 is shown directly or indirectly connected to or coupled to the heat sink 16. Device 20 can be considered a first temperature sensing device 20. Temperature sensing device 20 may also be mounted at other locations on the telescope. Temperature sensing device 20 measures the temperature of telescope 10. For example, temperature sensing device 20 may include a thermistor. In one example, temperature sensing device 20 is located away from heater 18. In another example, multiple temperature sensing devices 20 are present. According to one embodiment, a temperature calibration table can be used, for example, to determine the temperature of telescope 10 or any location therefrom by knowing the temperature at temperature sensing device 20.

[0029] The first temperature sensing device 20 is coupled to the heater operation (see...) Figure 3 The output of the first temperature sensor 20 is processed and used to control the heater. Software, protocols, instructions, or other logic communicate with the temperature sensor to maintain the telescope 10 at the desired temperature. A specific temperature that helps maintain the telescope within the desired operating temperature range is within 50 degrees Celsius ± 5%. The software controls the power supplied to the heater, thereby regulating the desired temperature. The control of the heater power is achieved through closed-loop control. Closed-loop control means that the temperature sensor on the telescope measures the temperature of the telescope. This temperature or data is provided to a PID control loop (Proportional-Integral-Derivative Control Loop), which generates a feedback signal to adjust the heater power supplied to the heater on the telescope, thereby always maintaining the temperature sensor reading at the desired setpoint. Therefore, the loop between the temperature sensor and the heater power is closed.

[0030] The system or telescope 10 also includes a second temperature sensing device 22, located near the telescope 10, which measures the air or space ambient temperature near the exterior 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 this disclosure utilizes sensors as part of the second temperature sensing device 22 to detect the ambient temperature near the telescope. Specifically, this embodiment may employ three independent ambient temperature sensors that collectively constitute the second temperature sensing device 22, wherein a first ambient temperature sensor detects the ambient temperature near the front end of the telescope 10, a middle ambient temperature sensor detects the ambient temperature near the middle of the telescope 10, and a third ambient temperature sensor detects the ambient temperature near the second end of the telescope 10. The ambient temperature sensors collectively constituting the second temperature sensing device 22 detect ambient temperatures to identify three different temperature zones around the telescope 10. The ambient temperatures may be the average of their individual values, or they may be used independently in the process of controlling the heater 18, as described herein.

[0031] Pressure sensor 24 is located near telescope 10 and measures the ambient pressure of the air or space near the outside of telescope 10. Pressure sensor 24 can also be an altimeter, since pressure and altitude are essentially directly related.

[0032] Figure 3 An exemplary embodiment of the control loop 30 for the heating mechanism of a precision focusable telescope is shown. A first temperature sensor 20 is mounted to the heat sink 16 of the telescope 10 or another part of the housing 12 for measuring the temperature of the telescope 10. A second temperature sensor 22 is located near the telescope 10 for measuring the ambient temperature of the air or space near the exterior of the telescope 10. A pressure sensor 24 is located near the telescope 10 for measuring the ambient pressure of the air or space near the exterior of the telescope 10.

[0033] Temperature feedback 32 from the first temperature sensing device 20 serves as input to a temperature digitization electronics device, which converts the temperature feedback or signal into a processable reading. Temperature feedback 32 is then transmitted to a summing module 34.

[0034] Temperature feedback 36 from the second temperature sensing device 22 serves as input to a temperature digitization electronics device, which converts the temperature feedback 36 or signal into a processable reading. The temperature feedback 36 is then transmitted to a temperature setpoint algorithm or temperature setpoint logic 38.

[0035] Ambient pressure feedback 40 from pressure sensing device 24 serves as input to temperature digitization electronics, which converts the pressure feedback or signal into a processable reading. Pressure feedback 40 is then transmitted to temperature setpoint algorithm or temperature setpoint logic 38.

[0036] Temperature setpoint logic 38 determines the temperature at which the telescope 10 or telescope housing 12 should operate to optimize diffraction-limited performance (≤±1 / 4 wavelength defocus) over a wide range of temperature and altitude environments. This allows the low f-number telescope 10 to compensate for its high sensitivity to environmental pressure and temperature.

[0037] Regarding setpoint logic 38, one exemplary 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. Therefore, in some embodiments, the ambient pressure sensor input is optional for setpoint logic 38. In some embodiments, the ambient temperature sensor input is optional for setpoint logic 38, and thus it uses only ambient pressure. Furthermore, if a large pressure and temperature gradient exists around the telescope, other embodiments allow setpoint logic 38 to use multiple pressure and temperature sensor inputs. For example, if the ambient temperatures around different ends of the telescope are different, simultaneously reading the temperatures of two regions may be beneficial for calculating the optimal focus setpoint temperature of the telescope 10. Setpoint logic 38 may include a lookup table for determining the optimal focus setpoint temperature of the telescope based on ambient pressure and temperature readings. The setpoint logic may perform a method that utilizes this lookup table to determine the optimal focus setpoint temperature of the telescope based on ambient pressure and temperature readings. Setpoint logic 38 may interpolate points in the lookup table. The temperature setpoint in the lookup table can be determined by performing calibration tests under the ambient temperature and pressure of the telescope or a representative telescope while simultaneously measuring the telescope's focal length.

[0038] Another configuration is that the setpoint logic 38 does not use a lookup table, but instead uses an equation, the coefficients of which are also determined by fitting calibration test data into the formula. For example, "Setpoint temperature = A*(ambient temperature) + B*(ambient pressure) + C", where the equation and coefficients A, B, and C are determined by the telescope design. The values ​​of A, B, and C will be based on the best fit between the equation and the calibration data.

[0039] The output 42 of the setpoint logic 38 (i.e., the desired telescope temperature) is transmitted to the summing module 34. The summing module 34 receives the output 42 of the setpoint logic 38 as its input. In addition, the summing module 34 also receives temperature feedback 32 from the first temperature sensing device 20 as its input.

[0040] The output of the summation module 34 serves as an input to the telescope temperature input control or controller 44. Controller 44 can be coupled to a sampling rate counter that outputs readings from two temperature sensors 20 and 20, respectively, as a 12-bit telescope temperature. This 12-bit telescope temperature can serve as an input to a 1-a filter unit that applies a filtering gain. The filtered telescope temperature can then serve as an input to the heater controller 44. In one example, controller 44 is a proportional-integral (PID) controller implemented in a controller such as a field-programmable gate array (FPGA). In one implementation, a temperature calibration table is used to provide a more accurate temperature for telescope 10.

[0041] The output of the PID controller 44 feeds the heater input to the switching power supply. For example, this switching power supply can be a buck, boost, buck-boost, isolated, or non-isolated type. The switching power supply regulates the voltage across the heater 18, which can be an electrofilm heater that applies heat to the heat sink 16, thereby maintaining the telescope 10 at the desired temperature to achieve diffraction-limited performance. In one embodiment, the temperature setpoint of the control loop 30 can be set by the user via a digital interface.

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

[0043] Figure 3 The power supplied to heater 18, which surrounds telescope 10, is shown. Another temperature sensor is located in the central housing of the telescope to detect the temperature at the center of the telescope. This temperature sensor (i.e., device 20) measures the temperature at the center of the telescope at a specific moment. This temperature signal is sent to a summing module. The summing module sums the data from the central temperature sensor with the setpoint temperature at which the system wants to control the telescope. If the measured temperature is not equal to the setpoint temperature, the summing module generates an error signal. In other words, if the temperature sensor data equals the setpoint temperature, there is no error output from the summing module. When an error signal occurs, it enters the PID control loop, i.e., the proportional controller. The proportional controller generates a signal to the heater, informing it of the power required to heat the telescope to the desired level of the setpoint temperature. This process is repeated until no more error signals occur. For example, if the setpoint temperature is lower than the actual temperature detected by the temperature sensor located in the central housing of the telescope, the PID controller will issue a command to shut off the power, thereby cooling the telescope. Conversely, if the temperature detected by the central temperature sensor is lower than the setpoint temperature, the PID controller will increase the power to the heater, thereby raising the temperature of the telescope. This forms a feedback loop, allowing this process to continue, continuously heating or cooling the telescope to maintain it at the desired setpoint temperature.

[0044] The system disclosed herein is an improvement upon conventional telescopes that use static or fixed temperatures to maintain the telescope at a preset temperature. In conventional systems or apparatuses, there is no feedback loop to responsively change the heater based on the telescope's temperature or altitude. This limits the telescope's focusing range, as it only allows the telescope to focus within a specific altitude range. By adding the feedback loop and PID controller of this disclosure, a system employing this improved technique can be used over a wider range of altitudes and temperatures, while keeping low f-number telescopes available over these wider altitude and pressure ranges. The setpoint calculator also acquires pressure data from a pressure sensor and calculates the pressure as a function of temperature or temperature-dependent. By measuring pressure and temperature, the setpoint calculator can determine the optimal focus of the telescope based on the temperature and pressure parameters. This can be calculated using a lookup table or pre-calibrated measurements, or it can be achieved through adaptive learning using artificial intelligence.

[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 every embodiment of the controller 44. However, for the purposes of this disclosure, the PID has proven to be reliable and efficient. Therefore, the PID can be part of the control loop, but PID control is not necessary as long as the control loop can still take temperature and pressure into account to dynamically power the heating elements around or on the telescope, thereby maintaining the telescope's defocus within the desired target range.

[0046] Figure 4 A method for focusing an optical system in a low F-number precision focusable telescope, denoted as 400, is illustrated according to one embodiment. In this example, method 400 includes designing an optical scheme to achieve linear performance, denoted as 402. The method also includes coarsely adjusting the telescope optical system to the desired focal length during assembly by aligning and adjusting the lens spacing, denoted as 404. The method further includes using a heater circuit to characterize the optimal telescope temperature for obtaining the optimal focal length within a defined temperature and altitude range, denoted as 406. The method may also include adjusting the heater driver setpoint temperature to fine-tune the focal length of the telescope optical system, denoted as 408. The method further includes maintaining the heater driver setpoint temperature over a wide temperature and a wide altitude range (from sea level to space) to achieve diffraction-limited performance, denoted as 410.

[0047] In one embodiment, the initial (coarse) adjustment of the desired focal length employs a conventional method, i.e., adjusting and setting the lens optics within the telescope housing 10 while the telescope is heated to an initial temperature. This method also includes adjusting the heater driver setpoint temperature to fine-tune the telescope optics system, denoted as 406. In one embodiment, fine (precise) adjustment of the focal length is achieved by changing the telescope temperature until diffraction-limited performance is achieved. This precise focal length adjustment by changing the telescope temperature until diffraction-limited performance is achieved using feedback 32 from a first temperature sensor 20, feedback 36 from a second ambient temperature sensor 22, and optionally feedback 40 from an ambient pressure sensor 24. In various embodiments, the temperature range used for focal length adjustment is greater than the highest ambient temperature of the air surrounding the telescope 10. The constant heat flow into the telescope 10 eliminates the need for a cooling system to maintain the temperature.

[0048] In one embodiment, the telescope 10 of this disclosure is an afocal telescope, wherein a collimated beam enters from a first end of the telescope and is focused to a focal point via a first pair of three-element lenses. The light then diffuses from this focal point to a second pair of three-element lenses. The light then passes through the second pair of three-element lenses, thus exiting from a second end of the afocal telescope as a collimated beam with a smaller diameter. The focal length is relatively short relative to the diameter of the optical lenses. This results in a low F-number.

[0049] like Figure 5 As shown, for a given telescope, as the f-number decreases, the telescope becomes more sensitive to the refractive index of air or other media. Figure 5 The differences in defocus and lens F-number are plotted for examples at sea level and different altitudes. Line 50A represents the defocus difference of a conventional telescope located in space or at extremely high altitudes (>100,000 feet) between sea level and extremely high altitudes. Line 50D represents the defocus difference of a conventional telescope located at an altitude of 10,000 feet between sea level and extremely high altitudes. Lines 50B and 50C represent two intermediate altitudes between sea level and space. As shown by lines 50A–50D, even at low altitudes, the defocus difference is significant for low F-number lenses (i.e., above the known defocus limit threshold of 0.25). Figure 5 The chart also shows that the 0.25 defocus limit (shown by the dashed line 52) is a generally accepted rule of thumb for sharp focus. See below. Figure 6A As shown, the telescope 10 disclosed herein is based on Figures 1-3 The structural configuration shown and Figures 3-4 The operation shown can be performed at a defocus limit below 0.25 (where the ± range of 0.25 is represented by a defocus range of 62).

[0050] Figure 6A and Figure 6BThis is a graph showing the defocus calculation performed using the second temperature sensor 22 and pressure sensor 24 based on the telescope 10. This defocus calculation simulates the residual defocus of the system. Figure 6B The diagram depicts the flight profile of a platform (which can be manned or unmanned), showing how its altitude changes over time. For example, as altitude increases, pressure decreases. For instance, at time zero, the altitude is at its lowest point, and the pressure is at its highest. As time progresses, altitude increases and pressure decreases.

[0051] Figure 6A The calculation of the defocus of the telescope 10 is shown when the temperature of the telescope 10 is controlled by the first temperature sensor 20, the second temperature sensor 22 and the pressure sensor 24. Figure 6A As shown, the target's out-of-focus PV wave should be within the out-of-focus range of 62, i.e., ±0.25 waves. Figure 6A The results show that, compared to the previous static system, the dynamic feedback loop temperature control system of telescope 10 is better able to keep the telescope within the target defocus range 62, thus achieving ideal results. For example, at time zero, heater 18 is not yet turned on, and all systems are in a relatively defocused state. However, as time progresses, the dynamic feedback loop temperature control system of telescope 10 heats telescope 10, causing it to quickly enter the defocus target range, as can be seen from line 60B located within range 62. Then, once heater 18 heats up telescope 10, the focusing effect of telescope 10 is even better. In older systems or conventional telescopes with static temperatures, the telescope never has a focused value when the platform supporting the system is on the ground. This can be seen from line 60A of the older static telescope, whose horizontal position is approximately 1.25 on the defocus vertical scale.

[0052] Line 60B indicates that before the platform leaves the ground, the temperature of telescope 10 is set to the desired temperature based on the ambient temperature and pressure sent to controller 44. As shown, the platform carrying the telescope takes off or begins its flight at approximately 45 minutes. The temperature of telescope 10 changes continuously, sensed by first and second temperature sensors 20, 22 and pressure sensor 24. However, the dynamic control system enables telescope 10 to remain within the target defocus bandwidth 62 throughout the flight, as shown in line 60B. This contrasts sharply with older static systems (as shown in line 60A), which can deviate from the defocus target range with changes in altitude and pressure. For example, in the older static design, at time T120, the platform begins to descend, resulting in increased pressure. The older design remained between approximately T135 and T195 (where... Figures 6A-6BThe time on the X-axis (represented by the capital letter T) will exceed the target defocus range 62. However, within the same time period from T135 to T195, the new system of telescope 10 is able to keep the defocus within the target bandwidth range 62, even with changes in altitude and pressure along the flight path, as can be seen from line 60B in the range 62 during the time period from T135 to T195.

[0053] While this disclosure describes the telescope housing 12 as being made of aluminum in one embodiment, other embodiments may use different materials to form the housing 12. However, these other embodiments should select materials with a sufficient CTE value. For example, as previously mentioned, titanium has a CTE value of approximately 9, which is too low for the desired purpose of a precision focusing telescope with a low f-number (i.e., f-number less than or equal to 2). Therefore, other materials used to form the telescope housing 12 should have a CTE value greater than 9. Another embodiment determines that copper has a CTE value of approximately 16, which is sufficient to improve the performance of a titanium housing. Therefore, other materials that can be used to form the telescope housing 12 should have a CTE value greater than 16. Table 1 lists some other exemplary materials with a CTE value greater than 9 that can be used to form the housing 12 according to other embodiments of this disclosure.

[0054] Table 1

[0055]

[0056]

[0057]

[0058]

[0059] In addition to the sufficiently high CTE value discussed above, the material used to manufacture the housing 12 should also have a sufficiently high thermal conductivity. For example, as previously mentioned, titanium has a thermal conductivity of approximately 22.4 t K at 0°C, which is too low for a low F-number (i.e., F-number less than or equal to 2) precision focusing telescope. Therefore, other materials used to manufacture the telescope housing 12 should have a higher thermal conductivity than titanium. Another embodiment determines that copper has a thermal conductivity of approximately 401 W / m K at 0°C, which is sufficient to improve the performance of the titanium housing. Therefore, other materials that can be used to manufacture the telescope housing 12 should have a thermal conductivity greater than approximately 100. According to other embodiments of this disclosure, Table 2 lists some other exemplary materials that can be used to manufacture the housing 12 and have a thermal conductivity greater than approximately 100.

[0060] Table 2

[0061]

[0062]

[0063]

[0064]

[0065] Although sensing devices 20, 22, and 24 have been described in detail herein, telescope 10 or its associated systems or components may also include one or more other sensors for sensing or collecting data related to the surrounding environment or the operation of the device, component, or system. Some exemplary sensors capable of electronically coupling to the devices, components, or systems of this disclosure (whether directly connected to or remotely connected to the devices, components, or systems of this disclosure) include, but are not limited to: accelerometers for sensing accelerations during rotation, translation, velocity / rate, position, and altitude increases; gyroscopes for sensing motion during angular orientation and / or rotation; altimeters for sensing air pressure, altitude changes, terrain elevation changes, local pressure changes, and liquid immersion; impellers for measuring the amount of fluid flowing through them; GPS sensors for sensing position, altitude, distance traveled, and velocity / rate; audio sensors for sensing local ambient sound levels or performing voice detection; and light sensors for sensing ambient light intensity, ambient temperature, day / night cycles, and ultraviolet radiation. Television / infrared sensors are used to sense light wavelengths; other temperature sensors are used to sense machine or motor temperature, ambient air temperature, and ambient temperature; humidity sensors are used to sense ambient humidity levels.

[0066] The apparatus, component, or system disclosed herein may include wireless communication logic coupled to sensors on the apparatus, component, or system. The sensors collect data and provide it to the wireless communication logic. The wireless communication logic then transmits the data collected from the sensors to a remote device. Therefore, the wireless communication logic may be part of a broader communication system in which one or more apparatus, component, or system of this disclosure may be networked for reporting alarms, and more generally, for remote access and control. Depending on the type of transceiver installed in the apparatus, component, or system of this disclosure, the system may communicate using various protocols, such as Wi-Fi, ZigBee, MiWi, and Bluetooth. In one example, each apparatus, component, or system of this disclosure may have its own IP address and may communicate directly with a router or gateway. This is typically the case if the communication protocol is Wi-Fi.

[0067] In another example, a point-to-point communication protocol similar to MiWi or ZigBee is used. One or more devices, components, or systems of this disclosure can be used as repeaters, or they can be connected together to form a mesh network to relay signals from one device, component, or system to another. However, in this scenario, individual devices, components, or systems typically do not have their own IP addresses. Instead, one or more devices, components, or systems of this disclosure communicate with a repeater that has an IP address or other addresses, identifiers, or credentials required for communication with external networks. The repeater communicates with a router or gateway.

[0068] Regardless of the communication scheme used, a router or gateway communicates with a communication network (such as the Internet); although in some implementations the communication network may be a private network using Transmission Control Protocol / Internet Protocol (TCP / IP) and other common Internet protocols, but does not interact with the wider Internet, or only selectively interacts through a firewall.

[0069] The system by which the devices, components, or systems of this disclosure receive and process signals may vary depending on the implementation. In one implementation, alarms and signals issued by the devices, components, or systems of this disclosure are sent via email or SMS service gateway, thereby being sent as emails or text messages to remote devices (e.g., smartphones, laptops, or tablets) monitored by a responsible person, team, or department (e.g., a maintenance department). Therefore, if a particular device, component, or system of this disclosure issues an alarm due to data points collected by one or more sensors, the alarm can be sent directly to the person responsible for repairing the device in the form of an email or text message. Of course, email and text messages are just two available communication methods; different communication methods may be used in other implementations.

[0070] The system also allows users to access the devices, components, or systems disclosed herein for configuration and diagnostics. In this case, the individual processors or microcontrollers of the devices, components, or systems disclosed herein can be configured to act as web servers, using protocols such as Hypertext Transfer Protocol (HTTP) to provide an online interface for configuring the devices, components, or systems. In some embodiments, the system can be used to configure multiple devices, components, or systems of the present disclosure simultaneously. For example, if multiple devices, components, or systems are of the same model and located in similar locations within the same area, it may not be necessary to configure them individually. Instead, the user can provide configuration information for multiple devices, components, or systems, including baseline operating parameters, all at once.

[0071] As described herein, certain aspects of this disclosure may include one or more electrical, pneumatic, hydraulic, or other similar auxiliary components and / or systems. Therefore, this disclosure should be understood to include any necessary operating components. For example, electrical components should be understood to include any suitable and necessary wiring, fuses, or similar parts required for their normal operation. Furthermore, it should be understood that any connection between the various components not expressly described herein can be achieved by any suitable means, including mechanical fasteners or more durable connection methods such as welding. Alternatively, where feasible and / or necessary, the various components of this disclosure may be integrally formed.

[0072] Various inventive concepts can be embodied in one or more methods, an example of which has been provided herein. The operations performed as part of this method can be ordered in any suitable manner. Therefore, several implementations can be constructed in which the order of operation execution differs from that illustrated, including performing certain operations simultaneously, even if they are shown as sequential operations in the exemplary implementation.

[0073] While various embodiments of the invention have been described and illustrated herein, those skilled in the art will understand that various other methods and / or structures exist to achieve the functions and / or results described herein and / or to realize one or more advantages described herein, and each such variation and / or modification should be considered within the scope of the embodiments of the invention described herein. More generally, those skilled in the art will understand that all parameters, dimensions, materials, and structures described herein are intended as examples, and actual parameters, dimensions, materials, and / or structures will depend on the specific application of the teachings of this invention. Those skilled in the art will recognize, or can determine by conventional experimentation alone, many equivalents of the specific embodiments of the invention described herein. Therefore, it should be understood that the above embodiments are given by way of example only, and that embodiments of the invention may be practiced in ways different from the specific descriptions and claims within the scope of the appended claims and their equivalents. The inventive step of this disclosure applies to each feature, system, article, material, kit, and / or method described herein. Furthermore, any combination of such features, systems, articles, materials, kits, and / or methods is also included within the inventive step of this disclosure if there is no contradiction between two or more such features, systems, articles, materials, kits, and / or methods.

[0074] The above-described embodiments can be implemented in various ways. For example, the technical embodiments disclosed herein can be implemented using hardware, software, or a combination of both. When implemented in software, the software code or instructions can be executed on any suitable processor or set of processors, whether such processors or sets of processors are located on a single computer or distributed across multiple computers. Furthermore, the instructions or software code can be stored in at least one non-transitory computer-readable storage medium.

[0075] In addition, computers or smartphones can execute software code or instructions through their processors and may be equipped with one or more input / output devices. These devices can be used for a variety of purposes, including presenting a user interface. Examples of output devices that can be used to provide a user interface include printers or displays for visual presentation of output, and speakers or other sound-emitting devices for auditory presentation of output. Examples of input devices that can be used for a user interface include keyboards and pointing devices such as mice, touchpads, and digitizers. For example, a computer can receive input information through speech recognition or other audio formats.

[0076] Such computers or smartphones can be interconnected via one or more networks in any suitable form, including local area networks (LANs) or wide area networks (e.g., corporate networks), intelligent networks (INs), or the Internet. These networks can be based on any suitable technology and operate according to any suitable protocol, and may include wireless networks, wired networks, or fiber optic networks.

[0077] The various methods or processes described herein can be written as software / instructions and executed on one or more processors that can operate on various operating systems or platforms. Furthermore, such software can be written using a variety of suitable programming languages ​​and / or programming or scripting tools, or compiled into executable machine language code or intermediate code and executed on a framework or virtual machine.

[0078] In this regard, various innovative concepts can be embodied in computer-readable storage media (or multiple computer-readable storage media) (e.g., computer memory, one or more floppy disks, optical disks, magnetic tapes, flash memory, USB flash drives, SD cards, field-programmable gate arrays or other semiconductor devices, or other non-transient media or tangible computer storage media) that are encoded with one or more programs that, when executed on one or more computers or other processors, can implement the various embodiments of the present disclosure described above. The computer-readable medium is portable, and therefore the programs stored thereon can be loaded onto one or more different computers or other processors to implement the various aspects of the present disclosure described above.

[0079] In this document, the terms "program," "software," or "instructions" are used in a general sense to refer to any type of computer code or set of computer-executable instructions that can be used to program a computer or other processor to implement the various implementation methods described above. Furthermore, it should be understood that, according to one aspect of the present invention, one or more computer programs executing the methods of this disclosure do not need to reside on a single computer or processor, but can be modularly distributed across multiple different computers or processors to implement the various aspects of this disclosure.

[0080] Computer-executable instructions can take various forms, such as program modules, and are executed by one or more computers or other devices. Typically, program modules include routines, programs, objects, components, data structures, etc., for performing specific tasks or implementing specific abstract data types. The functionality of program modules can typically be combined or allocated as needed in various implementations. Therefore, one aspect or implementation of this disclosure may be a computer program product comprising at least one non-transitory computer-readable storage medium operationally in communication with a processor, the storage medium storing instructions that, when executed by the processor, implement the methods or processes described herein, wherein these instructions include steps for performing the methods or processes detailed herein.

[0081] Furthermore, data structures can be stored in any suitable form on a computer-readable medium. For ease of illustration, fields in a data structure can be associated with each other by their position within the data structure. This association can also be achieved by assigning storage locations in a computer-readable medium that reflect the relationships between fields. However, any suitable mechanism can be used to establish relationships between fields in a data structure, including the use of pointers, labels, or other mechanisms capable of establishing relationships between data elements.

[0082] All definitions and usages herein should be understood to take precedence over dictionary definitions, definitions in incorporated documents, and / or the usual meaning of the defined terms.

[0083] As used herein, "logic" includes, but is not limited to, hardware, firmware, software, and / or combinations thereof, for performing one or more functions or actions, and / or triggering another logic, method, and / or system to perform a function or action. For example, depending on the required application or requirement, logic may include software-controlled microprocessors, discrete logic (e.g., processors, such as microprocessors), application-specific integrated circuits (ASICs), programmable logic devices, memory devices including instructions, electronic devices with memory, and so on. Logic may include one or more gates, combinations of gates, or other circuit elements. Logic may also be implemented entirely in software. If multiple logics are described, these logics can be integrated into a single physical logic. Similarly, if a single logic is described, that single logic can be distributed across multiple physical logics.

[0084] Furthermore, the logic proposed herein for implementing various methods of this system can be used to improve existing computer- or internet-centric technologies that may not have prior similar versions. This logic can provide specific functions directly related to the structure, thereby solving some of the problems identified herein. This logic can also significantly enhance the advantages of solving these problems by providing exemplary inventive concepts (as specific logical structures of methods and systems and their corresponding functions). Furthermore, this logic can provide specific computer implementation rules for improving prior art processes. The logic provided herein is not limited to collecting data, analyzing information, and displaying results. Moreover, some or all of this disclosure may rely on basic equations derived from the specific arrangement of the devices or components described herein. Therefore, the portions of this disclosure relating to the specific arrangement of components are not directed at abstract concepts. Furthermore, the content set forth in this disclosure and its appended claims relates to more than just performing activities known, conventional, and easily understood in the art. In some methods or processes of this disclosure, aspects of natural phenomena may be included, and the process or method steps may be new and useful additional features.

[0085] Unless otherwise expressly stated, the articles “a” and “an” used in this specification and claims shall be understood as “at least one”. The phrase “and / or” (if any) used in this specification and claims shall be understood as “one or both,” meaning that they exist in parallel in some cases and separately in others. Multiple elements listed with “and / or” shall be interpreted in the same way as “one or more” parallel elements. Other elements may be selectively present in addition to those expressly specified in the “and / or” clause, regardless of whether these elements are related to the expressly specified elements. Thus, as a non-limiting example, when “A and / or B” is used in conjunction with open-ended language such as “comprising,” in one embodiment it may refer only to A (optionally including elements other than B); in another embodiment it may refer only to B (optionally including elements other than A). In yet another embodiment, both A and B may be included (optionally including other elements); and so on. As used in this specification and claims, “or” shall 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, meaning it includes at least one element, multiple elements, and (optionally) other items not listed. Only terms that explicitly indicate the opposite meaning, such as “only one” or “exactly one”, or “consisting of” as used in a claim, refer to an element that includes one of multiple elements. Generally, the term “or” as used herein should only be interpreted as indicating a mutually exclusive choice (i.e., “either one, not both”) when preceded by an exclusive term (e.g., “one of both,” “only one,” or “exactly one”). The phrase “consisting primarily of” when used in a claim should have the usual meaning as used in the field of patent law.

[0086] As used in this specification and claims, the term "at least one," when referring to a list of one or more elements, should be understood to mean selecting at least one element from one or more elements in the list, but does not necessarily include every element specifically listed in the list, nor exclude any combination of elements in the list. This definition also allows for the presence of elements other than those specifically identified in the list referred to by "at least one," regardless of whether such elements are related to any element specifically identified in the list. Thus, as a non-limiting 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") in one embodiment may refer to at least one A (optionally including multiple A's) and exclude B (and optionally include other elements besides B); in another embodiment, it may refer to at least one B (optionally including multiple B's) and exclude A (and optionally include other elements besides A); in yet another embodiment, it may refer to at least one (optionally including multiple) A and at least one (optionally including multiple) B (and optionally including other elements); and so on.

[0087] Although the various components of this disclosure are described in relation to each other herein, any one of the components disclosed herein may also include inventive subject matter if used alone or claimed. For example, if the disclosed embodiments demonstrate features of components A and B, then unless otherwise stated herein, the combination of A and B, or A alone or B alone, may include inventive subject matter.

[0088] As used in this specification and claims, the word "achieve" or any phrase or claim element beginning with "achieve" should be understood as causing something to happen or facilitating the occurrence of something. For example, even if an event actually occurs or occurs to a second party, the actions of the first party may cause an event to occur. In other words, "achieve" means that one party provides tools, articles, or resources to another party, thereby facilitating the occurrence of an event. Therefore, in this example, the claim element "cause an event to happen" means that the first party provides the second party with the tools or resources necessary for the second party to carry out the event, but the specific actions of providing the tools or resources to facilitate the occurrence of the event are the responsibility of the first party.

[0089] In this document, when a feature or element is described as being "located" on another feature or element, it may be directly located on the other feature or element, and there may also be intermediate features and / or elements. Conversely, when a feature or element is described as being "directly located" on another feature or element, there are no intermediate features or elements. It should also be understood that when a feature or element is described as being "connected," "attached," or "coupled" to another feature or element, it may be directly connected, attached, or coupled to the other feature or element, and there may also be intermediate features or elements. Conversely, when a feature or element is described as being "directly connected," "directly attached," or "directly coupled" to another feature or element, there are no intermediate features or elements. Although the features and elements described or illustrated herein are given with reference to one embodiment, they are applicable to other embodiments as well. Those skilled in the art will also understand that references to structures or features "adjacent" to another feature may include portions that overlap with or are located below the adjacent feature.

[0090] For ease of description, this document may use spatial relative terms such as “below,” “under,” “lower,” “above,” “over,” “behind,” “front,” etc., to describe the relationships between the various elements or features shown in the figures. It should be understood that these spatial relative terms are intended to cover different orientations of the device other than those shown in the figures during use or operation. For example, if the device shown in the figures is inverted, elements described as “below” or “below…” will become “above….” Therefore, the exemplary term “below” can cover both “above…” and “below…” orientations. The device may also be in other orientations (e.g., rotated 90 degrees or other orientations), and the spatial relative descriptors used herein should be interpreted accordingly. Similarly, unless otherwise explicitly stated, the terms “up,” “down,” “vertical,” “horizontal,” “lateral,” “transverse,” “longitudinal,” etc., used herein are for illustrative purposes only.

[0091] Although the terms “first” and “second” may be used herein to describe various features / elements, these features / elements should not be limited by these terms unless the context otherwise requires. These terms are used to distinguish different features / elements. Thus, a first feature / element discussed herein may be referred to as a second feature / element, and similarly, a second feature / element discussed herein may be referred to as a first feature / element, without departing from the teachings of the invention.

[0092] The term "implementation method" refers to any implementation or example of the contents of this disclosure. The terms "implementation method," "one implementation method," "some implementation methods," "a specific implementation method," "an exemplary implementation method," or "other implementation methods" used in the specification refer to specific features, structures, or characteristics related to an implementation method that are included in at least some, but not necessarily all, implementation methods of the invention. Various forms of "implementation method," "one implementation method," "some implementation methods," "a specific implementation method," "an exemplary implementation method," or "other implementation methods" do not necessarily refer to the same implementation method.

[0093] If this specification indicates that a component, feature, structure, or characteristic "may," "may," or "possibly" include it, then that component, feature, structure, or characteristic is not necessarily required to be included. If the specification or claims refer to "an" element, it does not mean that there is only one such element. If the specification or claims refer to "an additional" element, it does not preclude the possibility that there may be multiple such additional elements.

[0094] As used in this specification and claims, including in the examples, unless otherwise expressly stated, all figures are to be understood to be prefixed with "about" or "approximately," even if the word is not explicitly used. "About" or "approximately" is used to describe the magnitude and / or location of a numerical value, thereby indicating that the described value and / or location is within a reasonably expected range. For example, a numerical value may be ±0.1%, ±1%, ±2%, ±5%, ±10%, etc., of the stated value (or range of values). Any range of values ​​described herein is intended to include all its subranges.

[0095] Furthermore, the methods described in this disclosure may be implemented in a different order than those described herein. Therefore, unless explicitly stated otherwise, any order of methods should not be considered a limitation. It is understood that performing certain steps of the method in a different order may also yield similar results.

[0096] In the aforementioned claims and specification, all transitional phrases such as “comprising,” “including,” “carrying,” “having,” “containing,” “involving,” “holding,” and “constituting of” should be understood as open-ended phrases, meaning “including but not limited to.” Only the transitional phrases “constituting of” and “mainly composed of” should be understood as closed or semi-closed transitional phrases, respectively. For specific definitions, please refer to the U.S. Patent and Trademark Office’s Patent Examination Procedure Manual.

[0097] The use of the word "invention" in various headings or sections of this specification is added in accordance with the guidelines / requirements of the United States Patent and Trademark Office for the formatting requirements of Word document submissions, and should in no way be considered an abandonment of any subject matter.

[0098] Certain terms have been used in the above description for the purpose of brevity, clarity, and ease of understanding. These terms are for descriptive purposes only and should be interpreted broadly; therefore, no unnecessary limitations beyond the requirements of the prior art should be inferred from them.

[0099] Furthermore, the descriptions and illustrations of various embodiments of this disclosure are merely examples, and this disclosure is not limited to the specific details shown or described.

Claims

1. A low F-number precision focusing telescope, comprising: A telescope housing comprising an interior and an exterior, wherein the interior of the telescope housing contains optical elements, wherein the optical elements in the telescope housing are associated with an F-number, and wherein the F-number is less than or equal to 2; A heater, which is directly or indirectly coupled to the telescope housing; A first temperature sensing device is used to detect the temperature of the telescope casing; A pressure sensing device is used to detect the pressure near the telescope housing; The controller communicates operationally with the first temperature sensor and the pressure sensor. The controller adjusts the heater in response to signals from the first temperature sensor and the pressure sensor, thereby maintaining the telescope housing at the desired temperature and thus preserving diffraction-limited performance.

2. The low F-number precision focusing telescope according to claim 1 further comprises: A second temperature sensing device is used to detect the temperature near the telescope housing; The controller communicates with the first temperature sensor, the second temperature sensor, and the pressure sensor, and adjusts the heater in response to signals from the first temperature sensor, the second temperature sensor, and the pressure sensor, thereby maintaining the telescope housing at the required temperature to achieve diffraction-limited performance.

3. The low F-number precision focusing telescope according to claim 2 further comprises: The summing device communicates operationally with the first temperature sensor, the second temperature sensor, and the pressure sensor, and communicates operationally with the controller; and The controller includes a proportional / integral controller, which has inputs and outputs; and A linear power supply includes an input and an output, wherein the input of the linear power supply receives an output signal from the proportional / integral controller; and wherein the output of the linear power supply regulates the voltage across the heater and controls the power applied to the heater, thereby maintaining the telescope at the desired temperature.

4. The low F-number precision focusing telescope according to claim 1, further comprising: A heat sink, comprising a first side and a second side, wherein the second side of the heat sink is coupled to at least a portion of the exterior of the telescope housing; The heater is directly coupled to the radiator.

5. The low F-number precision focusing telescope according to claim 4, further comprising: A gap pad is disposed between the exterior of the telescope housing and the heat sink.

6. The low F-number precision focusing telescope according to claim 1, wherein, The telescope's outer shell is made of a material with a coefficient of thermal expansion greater than 9.

7. The low F-number precision focusing telescope according to claim 6, wherein, The coefficient of thermal expansion is greater than 16.

8. The low F-number precision focusing telescope according to claim 1, wherein, The telescope's casing is made of aluminum.

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

10. The low F-number precision focusing telescope according to claim 1, wherein, The heater is an electric heater that includes a polyimide foil.

11. A method comprising: The temperature of the telescope housing is sensed using a first temperature sensing device, wherein the telescope housing includes an interior and an exterior, the interior of the telescope housing includes optical elements, wherein the optical elements in the telescope housing are associated with an F-number, and wherein the F-number is less than or equal to 2; The pressure is sensed near the telescope's outer shell using a pressure sensor. A controller that communicates with the first temperature sensor and the pressure sensor is used to adjust the heater, which is directly or indirectly coupled to the telescope housing, thereby achieving the diffraction-limited performance of the optical element in response to signals from the first temperature sensor and the pressure sensor.

12. The method of claim 11, further comprising: The temperature near the telescope housing is sensed using a second temperature sensor, wherein the controller communicates with the first temperature sensor, the second temperature sensor, the pressure sensor, and the controller. The heater is adjusted to maintain the telescope housing at the desired temperature, thereby achieving diffraction-limited performance in response to signals from the first temperature sensor, the second temperature sensor, and the pressure sensor.

13. The method of claim 12, further comprising: The summing device sums the signals from the first temperature sensor, the second temperature sensor, and the pressure sensor, wherein the summing device communicates with the controller. The output from the summing device is transmitted to the controller, wherein the controller includes a proportional / integral controller, which includes inputs and outputs; The output from the proportional / integral controller is received into a linear power supply, which includes inputs and outputs; and The voltage across the heater is regulated by the linear power supply, thereby controlling the power applied to the heater and maintaining the telescope housing at the desired temperature.

14. The method of claim 11, further comprising: By observing the optical design of the telescope, its linear performance can be obtained; Adjust the coarse adjustment of the telescope to the desired focal length; Adjusting the setpoint temperature is used for fine-tuning the telescope; The temperature of the telescope is changed until diffraction-limited performance is achieved, wherein the temperature change is achieved by using feedback from the first temperature sensing device and feedback from the second temperature sensing device.

15. The method according to claim 14, wherein, The temperature change is achieved by using feedback from the environmental pressure sensor.

16. A computer program product comprising at least one non-transient computer-readable storage medium located on a mobile platform, the mobile platform being operationally communicated with a computer processing unit in an optical system, the optical system having a housing, a first temperature sensing device for sensing the temperature of the housing, a second temperature sensing device for sensing the ambient temperature surrounding the housing, a pressure sensing device for sensing the ambient pressure surrounding the housing, and a heater directly or indirectly coupled to the housing, the storage medium storing instructions that, when executed by the computer processing unit, respond to signals from the first temperature sensing device, the second temperature sensing device, and the pressure sensing device to perform a process of maintaining the housing at a desired temperature, thereby achieving diffraction-limited performance, the instructions comprising: The temperature of the housing is determined using the first temperature sensing device; The temperature near the housing is determined using the second temperature sensor. The pressure sensor is used to determine the pressure near the housing; and The temperature of the housing is maintained at the desired temperature in response to feedback from the first temperature sensor, the second temperature sensor, and the pressure sensor.

17. The computer program product according to claim 16, wherein, The instruction also includes: The summing device sums the signals from the first temperature sensor, the second temperature sensor, and the pressure sensor, wherein the summing device communicates with the controller. The output from the summing device is transmitted to the controller, wherein the controller includes a proportional / integral controller, which includes inputs and outputs; The output from the proportional / integral controller is received into a linear power supply, which includes inputs and outputs; and The voltage across the heater is regulated by the linear power supply, thereby controlling the power applied to the heater and maintaining the telescope at the desired temperature.

18. The computer program product according to claim 17, wherein, The instruction also includes: By observing the optical design of the telescope, its linear performance can be obtained; Adjust the coarse adjustment of the telescope to the desired focal length; Adjusting the setpoint temperature is used for fine-tuning the telescope; and The temperature of the telescope is changed until diffraction-limited performance is achieved, wherein the temperature change is achieved by using feedback from the first temperature sensing device and feedback from the second temperature sensing device.

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