CA2635287A1 - Fully reflective, adjustable field size illuminator for solar simulation - Google Patents
Fully reflective, adjustable field size illuminator for solar simulation Download PDFInfo
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Abstract
A fully reflective, adjustable field size illuminator for solar simulation.
One or more lamps, that have housings with a reflective collector, are used to generate radiation with a spectral distribution that largely corresponds to the spectral distribution of sunlight. A segmented mirror assembly creates a uniformly illuminated source field in the beam that emerges from the housing(s). A reflective adjustable imaging device placed following the segmented mirror provides means to project an image of the uniform field and to easily and quickly change the location and corresponding size of the projected uniformly illuminated field and allows a large range field sizes to be selected without substantially deviating the spatial uniformity and spectral distribution at the target field. Air mass solar filters are used to adjust the spectrum to simulate the sun's true spectral distribution at various earth conditions.
One or more lamps, that have housings with a reflective collector, are used to generate radiation with a spectral distribution that largely corresponds to the spectral distribution of sunlight. A segmented mirror assembly creates a uniformly illuminated source field in the beam that emerges from the housing(s). A reflective adjustable imaging device placed following the segmented mirror provides means to project an image of the uniform field and to easily and quickly change the location and corresponding size of the projected uniformly illuminated field and allows a large range field sizes to be selected without substantially deviating the spatial uniformity and spectral distribution at the target field. Air mass solar filters are used to adjust the spectrum to simulate the sun's true spectral distribution at various earth conditions.
Description
FULLY REFLECTIVE, ADJUSTABLE FIELD
SIZE ILLUMINATOR FOR SOLAR SIMULATION
Field of the Invention The illuminator employs a unique fully reflective design in the optical system in order to achieve a high intensity, very uniformly illuminated field.
In solar simulators, in order to collect as much radiation as possible from an arc lamp, an ellipsoidal collecting mirror is commonly used, with the lamp near the inner focus.
Unfortunately, the illumination intensity across the output beam is very non-uniform. Commonly, solar simulators use refractive diffusers or integrators to create a uniform target field, but these also act to reduce brightness. In this illuminator a segmented beam-folding mirror assembly is placed in the beam emerging from the ellipsoid instead, so that the light from the arc lamp appears to come from a uniformly illuminated section near the face of the collecting mirror, thus providing significant improvement of the output on the target compared to using diffusers or integrators, and without wavelength limitations that arise with refractive components. Adjustable reflective optical components are placed following the folding assembly to project the uniformly illuminated field onto the desired target, and allowing the distance and corresponding size of the projected section to be easily and quickly changed, allowing a wide range of field sizes to be selected without substantial affect on the uniformity or spectral distribution at the target field.
The present invention relates to uniform field illuminators in general, and especially to solar simulators, with an optical system that uses a unique beam-folding segmented mirror assembly designed to increase the uniformity of the illumination at a target field without significant loss of power and allow user-controlled adjustment of the size of the target field without lengthy alignment procedures.
Background of the Invention Solar simulators are used to simulate natural sunlight in order to study the effects of sunlight on certain objects to be irradiated.
Many prior art solar simulators capture light from a xenon arc lamp using an ellipsoidal or parabolic reflector due to its superb geometric efficiency.
Unfortunately, the illumination pattern across the beam that emerges from the reflector is very non-uniform. Near the ellipsoid face the cross-section is a brightly illuminated disk with a dark hole in the middle, the brightness within the disk dimming toward the outer edge. This changes to a pattern at the ellipsoid focus that is bright at the center but dims continuously with distance from the center.
Further, it is not possible to find a uniformly illuminated cross-section that contains a large portion of the radiation anywhere along the beam. These non-uniform illumination patterns are unacceptable for many applications.
SIZE ILLUMINATOR FOR SOLAR SIMULATION
Field of the Invention The illuminator employs a unique fully reflective design in the optical system in order to achieve a high intensity, very uniformly illuminated field.
In solar simulators, in order to collect as much radiation as possible from an arc lamp, an ellipsoidal collecting mirror is commonly used, with the lamp near the inner focus.
Unfortunately, the illumination intensity across the output beam is very non-uniform. Commonly, solar simulators use refractive diffusers or integrators to create a uniform target field, but these also act to reduce brightness. In this illuminator a segmented beam-folding mirror assembly is placed in the beam emerging from the ellipsoid instead, so that the light from the arc lamp appears to come from a uniformly illuminated section near the face of the collecting mirror, thus providing significant improvement of the output on the target compared to using diffusers or integrators, and without wavelength limitations that arise with refractive components. Adjustable reflective optical components are placed following the folding assembly to project the uniformly illuminated field onto the desired target, and allowing the distance and corresponding size of the projected section to be easily and quickly changed, allowing a wide range of field sizes to be selected without substantial affect on the uniformity or spectral distribution at the target field.
The present invention relates to uniform field illuminators in general, and especially to solar simulators, with an optical system that uses a unique beam-folding segmented mirror assembly designed to increase the uniformity of the illumination at a target field without significant loss of power and allow user-controlled adjustment of the size of the target field without lengthy alignment procedures.
Background of the Invention Solar simulators are used to simulate natural sunlight in order to study the effects of sunlight on certain objects to be irradiated.
Many prior art solar simulators capture light from a xenon arc lamp using an ellipsoidal or parabolic reflector due to its superb geometric efficiency.
Unfortunately, the illumination pattern across the beam that emerges from the reflector is very non-uniform. Near the ellipsoid face the cross-section is a brightly illuminated disk with a dark hole in the middle, the brightness within the disk dimming toward the outer edge. This changes to a pattern at the ellipsoid focus that is bright at the center but dims continuously with distance from the center.
Further, it is not possible to find a uniformly illuminated cross-section that contains a large portion of the radiation anywhere along the beam. These non-uniform illumination patterns are unacceptable for many applications.
2 ti To create a uniform illumination pattern, most prior art solar simulators (for instance the Oriel solar simulators) use an optical integrator or a diffuser to disperse the light. This eliminates the dark spot in the middle, but a lot of light is lost through the dispersion process, making it inefficient. In addition, this loss is also not uniform across the spectrum, as more UV light is lost than visible or IR
light. This means the diffuser distorts the spectrum in addition to losing light. As well, the integrators and diffusers increase the angular size of the beam, reducing the luminance at the target field. Also, this approach produces a uniform field of fixed size. To change the field size requires significant changes to the properties and/or the positioning of the optical components, made more difficult due to the increased angular size, and often completely different optical components are needed.
Therefore a solar simulator is needed that does not have these problems.
This need is met by providing a more efficient illuminator that produces a uniformly illuminated cross-section without the spectral distortion of diffractive elements. The fully reflective illuminator of the present invention does not use a diffuser.
Instead, it uses a multi-segmented mirror that divides the outer disc at the ellipsoid face into sections and "folds" these towards the center so that, seen through the segmented mirror assembly, the sections of the ellipsoid face appear to overlap, so that the beam appears to emerge from a uniformly illuminated cross-section
light. This means the diffuser distorts the spectrum in addition to losing light. As well, the integrators and diffusers increase the angular size of the beam, reducing the luminance at the target field. Also, this approach produces a uniform field of fixed size. To change the field size requires significant changes to the properties and/or the positioning of the optical components, made more difficult due to the increased angular size, and often completely different optical components are needed.
Therefore a solar simulator is needed that does not have these problems.
This need is met by providing a more efficient illuminator that produces a uniformly illuminated cross-section without the spectral distortion of diffractive elements. The fully reflective illuminator of the present invention does not use a diffuser.
Instead, it uses a multi-segmented mirror that divides the outer disc at the ellipsoid face into sections and "folds" these towards the center so that, seen through the segmented mirror assembly, the sections of the ellipsoid face appear to overlap, so that the beam appears to emerge from a uniformly illuminated cross-section
3 that contains the largest portion of the available radiation. Following the segmented mirror assembly, a set of reflective mirrors is placed along the beam that projects a real image of this uniform field and allows the image size to be selected by a mechanical assembly that adjusts the mirror positions with a single motion, changing the distance and the corresponding size of the projected field.
The result is less light loss and no spectral distortion as found with refractive diffuser based solar simulators. This fully reflective principle makes the solar simulators of the present invention much more efficient than other single source solar simulators, and the reflective projection assembly allows a single unit to be used for a range of target sizes.
One solar simulator of the present invention includes the following: a high pressure xenon arc lamp for generating radiation with a spectral distribution which largely corresponds to the spectral distribution of sunlight, lamp power supply with optional optical feedback intensity stabilizer, air cooled or water cooled lamp housing with ellipsoidal reflector, beam conditioning optical components that produce and project a uniformly illuminated target field, optional fast electronic shutter with control box, and spectral filters.
The spectral distribution is tailored to the different application's needs with easily removed transmission and reflection filters that can be inserted in a beam conditioner. This effectively provides combinations of solar spectra, UV or IR
illumination and spectra for particular applications. For example the spectral
The result is less light loss and no spectral distortion as found with refractive diffuser based solar simulators. This fully reflective principle makes the solar simulators of the present invention much more efficient than other single source solar simulators, and the reflective projection assembly allows a single unit to be used for a range of target sizes.
One solar simulator of the present invention includes the following: a high pressure xenon arc lamp for generating radiation with a spectral distribution which largely corresponds to the spectral distribution of sunlight, lamp power supply with optional optical feedback intensity stabilizer, air cooled or water cooled lamp housing with ellipsoidal reflector, beam conditioning optical components that produce and project a uniformly illuminated target field, optional fast electronic shutter with control box, and spectral filters.
The spectral distribution is tailored to the different application's needs with easily removed transmission and reflection filters that can be inserted in a beam conditioner. This effectively provides combinations of solar spectra, UV or IR
illumination and spectra for particular applications. For example the spectral
4 distribution of the xenon light source along with specially designed Air Mass filters, can simulate the sun's true spectral distribution at various earth conditions (i.e. sun directly overhead or at other zenith angles) or even space conditions (no atmosphere).
For applications which require a better match to the solar spectrum at longer wavelengths than can be obtained with a Xenon lamp and filters a dual lamp source can be used. This employs both a xenon arc lamp with an ellipsoidal collector, and a tungsten filament incandescent lamp with a separate ellipsoidal collector, and a dichroic mirror that combines the beams emerging from the lamps in a manner such that the two ellipsoid faces appear to be coincident as seen through the dichroic mirror, the dichroic mirror having spectral characteristics such that in the combined beam the longer wavelengths of the arc lamp are substantially removed and replaced by the longer wavelengths of the incandescent lamp.
In contrast to the state of art solar simulators the solar simulators of the present invention include dedicated Air Mass Filters. These solar air mass filters are much more efficient than prior art filters because they do not require stacking.
Some Air Mass Filters used in prior art solar simulators are required to be placed in series to achieve the desired air mass rating. For example, both AMO and together are to be used in series to achieve AM1 performance. Unfortunately such a design requirement means twice the filter cost and extra loss of light. The Air
For applications which require a better match to the solar spectrum at longer wavelengths than can be obtained with a Xenon lamp and filters a dual lamp source can be used. This employs both a xenon arc lamp with an ellipsoidal collector, and a tungsten filament incandescent lamp with a separate ellipsoidal collector, and a dichroic mirror that combines the beams emerging from the lamps in a manner such that the two ellipsoid faces appear to be coincident as seen through the dichroic mirror, the dichroic mirror having spectral characteristics such that in the combined beam the longer wavelengths of the arc lamp are substantially removed and replaced by the longer wavelengths of the incandescent lamp.
In contrast to the state of art solar simulators the solar simulators of the present invention include dedicated Air Mass Filters. These solar air mass filters are much more efficient than prior art filters because they do not require stacking.
Some Air Mass Filters used in prior art solar simulators are required to be placed in series to achieve the desired air mass rating. For example, both AMO and together are to be used in series to achieve AM1 performance. Unfortunately such a design requirement means twice the filter cost and extra loss of light. The Air
5 Mass Filters of the present invention on the other hand, are dedicated filters. So to achieve AM1, only one AM1 filter is needed.
One disadvantage of the solar simulator described so far is that positions of the reflective mirrors that follow the segmented mirror need to be adjusted to change the distance at which the uniformly illuminated target field is projected.
This means the target field size cannot be easily adjusted as the mirror positioning is different for each target size setting. To overcome this disadvantage an adjustable focus device was developed that allows the mirrors to be repositioned for a wide range of target sizes with a single lever action.
Another minor disadvantage of the solar simulator of the present invention is its large physical size. This is due to the added space needed for the fully reflective mirrors that fold the light from the source to the target as compared to a simple diffuser. To minimize this size disadvantage, a vertical stand option can be provided such that the longer dimension can be placed vertically which minimizes its footprint requirement.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.
One disadvantage of the solar simulator described so far is that positions of the reflective mirrors that follow the segmented mirror need to be adjusted to change the distance at which the uniformly illuminated target field is projected.
This means the target field size cannot be easily adjusted as the mirror positioning is different for each target size setting. To overcome this disadvantage an adjustable focus device was developed that allows the mirrors to be repositioned for a wide range of target sizes with a single lever action.
Another minor disadvantage of the solar simulator of the present invention is its large physical size. This is due to the added space needed for the fully reflective mirrors that fold the light from the source to the target as compared to a simple diffuser. To minimize this size disadvantage, a vertical stand option can be provided such that the longer dimension can be placed vertically which minimizes its footprint requirement.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.
6 Brief Description of the Drawings FIG. I is a schematic top view of a solar simulator as an embodiment of the present invention FIG. 2 and FIG. 3 are schematic side views of an arc lamp housing to be used in the embodiment of FIG. 1.
FIG. 4 is a schematic top view of a beam conditioner to be used in the embodiment of FIG. 1.
FIG. 5 is a ray trace diagram illustrating the fully reflective design of a solar simulator of the present invention.
FIG. 6 includes diagrams illustrating a compensated spectral distribution of the light from a solar simulator of the present invention as compared with the spectral distribution of the natural sunlight.
FIG. 7 is a schematic view of a typical Water Cooled IR Filter to be used in a beam conditioner of FIG. 4.
FIG. 8 is a schematic side view of a solar simulator mounted horizontally as an embodiment of the present invention.
FIG. 4 is a schematic top view of a beam conditioner to be used in the embodiment of FIG. 1.
FIG. 5 is a ray trace diagram illustrating the fully reflective design of a solar simulator of the present invention.
FIG. 6 includes diagrams illustrating a compensated spectral distribution of the light from a solar simulator of the present invention as compared with the spectral distribution of the natural sunlight.
FIG. 7 is a schematic view of a typical Water Cooled IR Filter to be used in a beam conditioner of FIG. 4.
FIG. 8 is a schematic side view of a solar simulator mounted horizontally as an embodiment of the present invention.
7 FIG. 9 is a schematic side view of a solar simulator mounted vertically as an embodiment of the present invention.
FIG. 10 is a schematic diagram illustrating alignment of a beam conditioner of FIG.
4.
FIG. 11 is a schematic view of an adjustable focus device to be used in a beam conditioner of FIG. 4.
FIG. 12 is a schematic view of a solar simulator with an adjustable focus device installed in a beam conditioner as an embodiment of the present invention.
Description of the Preferred Embodiments Shown on FIG. 1, the first embodiment of the solar simulator of the present invention includes the following: a high pressure xenon arc lamp for generating radiation with a spectral distribution which largely corresponds to the spectral distribution of sunlight, adjustable lamp power supply with optional optical feedback intensity stabilizer and/or computer control of output power, air cooled or water cooled lamp housing with ellipsoidal reflector, beam conditioner to obtain and project a uniformly illuminated field, optional fast electronic shutter with control box, UV or air mass solar filters that can be quickly exchanged or removed through an access door, optional infrared (IR) water filter with quartz windows.
FIG. 10 is a schematic diagram illustrating alignment of a beam conditioner of FIG.
4.
FIG. 11 is a schematic view of an adjustable focus device to be used in a beam conditioner of FIG. 4.
FIG. 12 is a schematic view of a solar simulator with an adjustable focus device installed in a beam conditioner as an embodiment of the present invention.
Description of the Preferred Embodiments Shown on FIG. 1, the first embodiment of the solar simulator of the present invention includes the following: a high pressure xenon arc lamp for generating radiation with a spectral distribution which largely corresponds to the spectral distribution of sunlight, adjustable lamp power supply with optional optical feedback intensity stabilizer and/or computer control of output power, air cooled or water cooled lamp housing with ellipsoidal reflector, beam conditioner to obtain and project a uniformly illuminated field, optional fast electronic shutter with control box, UV or air mass solar filters that can be quickly exchanged or removed through an access door, optional infrared (IR) water filter with quartz windows.
8 This Solar Simulator illustrated in FIG. 2 uses a high pressure Xenon arc lamp.
As well as visible and infrared radiation, the Xenon lamp emits nearly 6% of the power it consumes in the IV region below 380 nm. The arc is a nearly ideal point source of light, and its brilliance can exceed that of the sun. The Xe lamp is mounted in a horizontal position inside the lamp housing, with the arc near the inner focus of the ellipsoidal reflector, one end protruding through a hole in the center back of the reflector, the other end in the center of the reflectors from face. The ellipsoid collects light from the arc and reflects it forward through the front face and light shines outwards through the front of the housing except where blocked by the electrode end of the lamp in the center. The output beam converges down to a small focal spot some distance away near the external focus of the ellipsoid. As shown in FIG.
3, the housing is cooled by forced air or water. For some applications HgXe lamps and Hg lamps can be used with is an additional shroud in the housing to make a lamp cooler.
Short arc lamps ranging from 450W to 1600W power or higher can be accommodated in the housing.
The arc lamp housing produces a focused beam with an ellipsoidal reflector because this is the most efficient geometric shape for collecting light from a point source and refocusing it to another point some fixed distance away. Since an arc lamp is not a perfect point source the resulting focal spot size is also not infinitesimally small: typically about 7mm-20mm in diameter depending on the power and arc gap size of the arc lamp itself. Important characteristics of the arc lamp
As well as visible and infrared radiation, the Xenon lamp emits nearly 6% of the power it consumes in the IV region below 380 nm. The arc is a nearly ideal point source of light, and its brilliance can exceed that of the sun. The Xe lamp is mounted in a horizontal position inside the lamp housing, with the arc near the inner focus of the ellipsoidal reflector, one end protruding through a hole in the center back of the reflector, the other end in the center of the reflectors from face. The ellipsoid collects light from the arc and reflects it forward through the front face and light shines outwards through the front of the housing except where blocked by the electrode end of the lamp in the center. The output beam converges down to a small focal spot some distance away near the external focus of the ellipsoid. As shown in FIG.
3, the housing is cooled by forced air or water. For some applications HgXe lamps and Hg lamps can be used with is an additional shroud in the housing to make a lamp cooler.
Short arc lamps ranging from 450W to 1600W power or higher can be accommodated in the housing.
The arc lamp housing produces a focused beam with an ellipsoidal reflector because this is the most efficient geometric shape for collecting light from a point source and refocusing it to another point some fixed distance away. Since an arc lamp is not a perfect point source the resulting focal spot size is also not infinitesimally small: typically about 7mm-20mm in diameter depending on the power and arc gap size of the arc lamp itself. Important characteristics of the arc lamp
9 housing are the size of the output face and the convergence of the output beam ad determined by the f/# of the ellipsoidal reflector.
Using a 1000W xenon lamp, the housing can generate over 80W of broadband photon power at the focal spot, with 26W-33W in the visible spectrum (400nm-700nm) alone. Such power produces a lot of heat. The exit port is normally covered with a 4.5" diameter quartz window to filter out harmful UVB rays.
However, UVA rays down to 270nm can still go through. If no UV rays are desired, and optional BK7 glass safety window is available to filter out most harmful UV rays below 360nm.
For UV applications, an optional fused silica version which allows all wavelengths including UV light above 200nm to pass through can be used.
An f/2.5 ellipsoidal reflector is employed in this lamp housing. It is made of precision diamond turned solid aluminum piece to bear the exact geometry of an ellipsoidal surface for accurate refocusing of the light from the arc to a small focal point in front of the housing. It is also thermally balanced to assure it does not warp under tremendous heat from the arc lamp as the interior of the lamp housing can reach 200 C. It is also specially coated to reflect all wavelengths ranging from ultraviolet to infrared. To keep the arc lamp housing cooled, a blower at the top draws air from the back of the housing and blows it over the arc lamp, as shown in FIG. 3.
For ozone producing lamps, a water-cooling of the housing must be used such that the ozone can remain inside the arc lamp housing.
The arc lamp housing is designed to work with 500W, 1000W, and 1500W or larger power adjustable power supplied with built-in igniters. These power supplied are highly stabilized switching DC power supplied that can be adjusted above or below its rated power. For example, the 500W power supply can be adjusted between 350W and 600W, the 1000W power supply can be adjusted between 800W and 1200W and the 1500W power supply can be adjusted between 1000W
and 1900W. An optional Optical Feedback Intensity Stabilizer with a built-in fibre optic light sensor can be used to monitor the light intensity of the arc lamp and automatically adjust the power supply to maintain a consistent non-fluctuating intensity. The system uses a fibre-optic cable to sample and direct the arc lamp light to the feedback/computer control unit. The Optical Feedback Intensity Stabilizer is a microprocessor based stand-alone unit which has an external light sensor that monitors the intensity of light and automatically adjusts the power supply upwards or downwards in real time to compensate for any detected intensity fluctuations.
Light proceeds from the ellipsoidal reflector through the beam conditioner system as shown on the FIG. 4. The beam conditioner includes a segmented folding mirror that forms a uniformly illuminated field and a double imaging system that projects an image of the field to the target location.
Light from the elliptical reflector in the arc lamp housing is directed (through the optional water-cooled IR filter) first to a 6-segment mirror assembly.
These segments fold light from different sections of the elliptical reflector face, so that the sections appear to overlap each other, forming a virtual uniformly illuminated field near the position of the ellipsoid face. FIG. 10 shows how two sections from opposite sides of the reflector face can be overlapped, so that the dark region in the 8 center of the face is eliminated, and the decrease in intensity from the insides of the sections to the outsides tends to cancel out. The 6-segment mirror assembly forms three such overlapping pairs on top of each other so light from the entire face of the ellipsoid is used to create the virtual uniform field.
The light then proceeds to a first concave mirror that mirror forms the first real image of the uniform field. The flat mirror directs the beam from the first concave mirror to the output concave mirror which projects the image to a location outside the solar simulator enclosure. The positions of the flat mirror and the output concave mirror can be adjusted with a mechanical linkage that allows the distance of the projected field from the housing to be selected according to the size required for the field. Two stages of imaging are used to provide large field sizes at moderate distances - with only one stage the distance for any particular size of field would need to be much larger.
The beam path carries light through the solar filter (AMO, AM1.0, AM1.5, AM2.0, etc), which is air-cooled by a cooling fan. The solar filters may be replaced while the main sheet metal cover is in place by using the access door at the top of the unit.
An interchangeable reflector mount allows the flat reflector to be replaced by a dichroic mirror (hot/cold mirror) to isolate a specific portion of the spectrum. When a hot/cold mirror is used, heat transmitted from the reflector is drawn away by a water-cooled heat sink behind it.
An optional electronically controlled shutter inside the beam conditioner can be used to control exposure time. An arc lamp is not designed to be frequently turned on and off as a 20,000 V spark is required to ignite it each time. Frequent ignition dramatically lowers the service life of the lamp. That is why for quick exposures, a shutter is recommended rather than switching the Solar simulator light source on and off.
The Beam Conditioner eliminates the necessity for refractive homogenizers, beam diffusers or beam integrators and allows uniform illumination to be obtained with higher efficiency. The beam conditioner system delivers more than 70% of the energy present at the secondary focus of the reflector. The uniformity at the target field is within 10% for the full field size (edge to edge) and 3% over a central area.
The spectral coverage is dependent on the type of arc lamp being used. Since the system is totally reflective (apart from plane parallel windows that do not affect ray directions) there are no chromatic aberrations. Front windows of Pyrex, Quartz or W fused silica can be selected, allowing the unit to be purged for work below 200 nm.
To summarize, the optical system works by using a unique segmented mirror beam-folding arrangement that eliminates the central dark spot usually found with ellipsoid based arc lamp systems, so that the folded ellipsoid face appears to be a very uniformly illuminated field. This virtual uniform field is then projected to a target at a selectable distance and corresponding size outside the housing and size.
A ray trace diagram illustrating the fully reflective design of a solar simulator of the present invention is shown on FIG. 5.
The solar simulator of the present invention, when used with an ozone free xenon arc lamp without any filters, provides a broadband spectral range of 250nm-2500nm.The Air Mass filters and filter combinations allow simulation of various solar conditions, modifying the spectral output of the arc lamp to match specific natural solar conditions (FIG. 6). Some particular filters, shown in the table below, are as follows:
Filter Type Simulated Environment Zenith Angle Air Mass 0 Filter (AMO) Outer Space 00 Air Mass 1.0 Direct Filter Direct solar spectrum on the ground 00 Air Mass 1.5 Direct Filter Direct solar spectrum on the ground 48.2 Air Mass 1.5 Global Filter Global solar spectrum (direct and diffuse) 48.2 on the ground Air Mass 2.0 Direct Filter Direct solar spectrum on the ground 60.10 The AMO filter corrects the output of the arc lamp to simulate the solar spectrum outside of the earth's atmosphere.
The Air Mass 1.0 Direct Filter corrects the output of the arc lamp to simulate the spectrum of the radiation on the ground coming directly from the sun when it is directly overhead (zenith angle 0 ).
The Air Mass 1.5 Direct Filter corrects the output of the arc lamp to simulate the radiation on the ground coming directly from the sun when the zenith angle is 48.2 .
The Air Mass 1.5 Global Filter corrects the output of the arc lamp to simulate the solar spectrum on the ground when the sun is at a zenith angle of 48.2 ;
however the filter also accounts for the diffuse light that is scattered by the atmosphere. As a result, this filter simulates the spectrum of the total radiation, known as global radiation that reaches the ground.
The Air Mass 2.0 Direct Filter corrects the output of the arc lamp to simulate the direct solar radiation at the ground when the sun is at a zenith angle of 60.10.
Filters in the solar simulator of the present invention for air masses larger than AM1.0 were redesigned in such way that they do not need to be used with AMO
and AM1 filters, a technique known as stacking in many prior solar filter designs.
This results in increased transmission efficiency as only one filter is required in the beam path rather than three. This also results in significant cost savings. For example, the previously used AM1.5G filtering is typically the least efficient because it requires other solar filters AMO and AM1 to be placed in front of the 1.5G filter.
After all three filters are placed in series, the previous AM1.5G efficiency is typically less than 40%.
However the stand-alone AM1.5G filter used in the solar simulator of the present invention does not require other solar filters to be stacked with it, resulting in approximately 60% higher throughput.
Additional filtering can be used if the application requires removing the IR
wavelengths longer than 1000nm. There is mounting space inside the solar simulator's beam conditioner unit where an IR water filter (FIG. 7) can be placed to eliminate IR light while preserving UV light, right after the lamp housing and before the first internal mirror, where the beam size is smallest.
The IR absorbing water filter absorbs infrared light between 1000-3000nm.
When filled with 12 distilled water, it absorbs nearly 100% of all IR light in this spectral range while transmitting approx 98% of all visible light between 350nm-700nm. If silica windows are used it also absorbs little UV light between 200nm-350nm, transmitting nearly 80%. This filter has a re-circulated water jacket to cool the filter itself making it excellent for high power applications. The filter body can be made of aluminum or stainless steel. Aluminum is used where only distilled water is to be used. Stainless steel is used when the absorbing media is water, copper sulfate or nickel sulfate.
FIG. 8 and FIG. 9 represent second and third embodiments of the solar simulator of the present invention in horizontal and vertical configurations.
FIG. 8 is basically a side view of the same embodiment as shown on FIG. 1. FIG. 9 is also equivalent to the first embodiment, except that a vertical stand and beam folding output mirror are added to achieve a downward pointing vertical configuration.
The stand and beam folding output mirror enable the fully reflective solar simulator to project its output beam downwards onto a horizontal illumination table, which makes it convenient for solar cell testing. The beam is projected down onto a built-in platform (not shown) where the target sample, such as a solar cell, is placed. With this stand the distance from the output port of the solar simulator to the sample platform can be set to provide 1 SUN intensity (100mW/cm2 using an AM1.5G filter or 136mW/cm2 using an AMO filter); on a 5" diameter target area for a 500W Xe lamp solar simulator, 7" diameter for 1000W Xe lamp solar simulator, 8" diameter for an 1600W Xe lamp solar simulator, or 12" diameter for an 2400W Xe lamp solar simulator.
The invention as described so far uses a unique beam-folding segmented mirror assembly designed to both increase the uniformity of the output while simultaneously not decreasing the power. While this allows us much better input/output power ratios relative to prior art solar simulators, once mirror positions are set the uniform field is projected to a specific location outside the solar simulator body, with a specific size.
Every time a different target size is needed, the plane mirror and the output concave mirror inside the solar simulator that project the uniform field onto the target need to be repositioned. Although this can be performed manually, the procedure is inconvenient should the user need to change the target size frequently. The solar simulator would need to be shut down and have the mirrors re-adjusted to support the new target size. To rectify this situation, an adjustable focus device was developed to easily and quickly change the distance and size of the projected uniform field without need to even open the housing of the system. Two mirrors ride on tracks, attached at fixed angles to maintain the optical path of the system, and are coupled so as to allow a wide range of adjustment to the output beam with a single, simple motion. The system can handle target distances as close as 20cm to a number of meters away without modification, so that the size of the target field can be as small as 3" or as large as wanted. With this adjustable focus device, re-positioning the internal mirrors of the solar simulator is performed through a single lever action, with no need to even shut the solar simulator down. This feature can also be used to vary illumination intensity by spreading the light over a larger area or concentrating the light into a smaller area.
The adjustable focus device itself shown of FIG. 11 is composed of two moving mirrors; a flat metallic mirror, and a concave focusing mirror. The two mirrors are mounted directly to cartridges which slide along flat tracks: the cartridges are slaved to each other (and therefore cannot move independently). It's important that the tracks on which the mirrors slide are aligned parallel to the optical path: the flat mirror slides along the path of the beam coming from the first concave mirror, and the concave output mirror moves along the path of the output beam. The angles of the mirrors do not change.
In order to ensure that the beam reflected from the flat mirror remains centered on the output mirror as the assembly is adjusted, the two mirror mounts are linked by a small metal bar, which is bolted in place on the focus-mirror side but slides freely between two pins on the base of the flat mirror. By this method the two mirrors are slaved together and maintain their proper positions along the optical path.
When the adjustable focus device is installed in the beam conditioner of the solar simulator (FIG. 12) with a specific optical path and the images of the uniform field within the system are at the appropriate places (i.e.: the system has been aligned properly), the device allows the user to project the uniform field over a range of distances along the output beam and corresponding sizes without lengthy alignment procedures. This without any significant lose of energy due to filters or beam homogenizers. While the additional projection optics unquestionably reduce the throughput of the 14 solar simulator by some small amount, the extra loss can be less than 5%.
Solar simulators, due to their highly specialized optics, are normally aligned for a specific target field size at a specific distance from the output of the system (e.g. a 30cm spot at 60cm from the housing). With the adjustable focus device, a much wider range of field sizes can be implemented at various distances with little or no technical knowledge required.
In order to ensure that the solar simulator system with the adjustable focus device operates according to specifications, it is important that the optics (the mirrors in this case) is within design specifications. Specifically, the mirror should be capable of reflecting UV, the accuracy of the focal length in the camera mirror must be high, and the angle at which the tracks are located must be within a few fractions of a degree (otherwise the spot will not be uniform to any useable level). The physical distance the adjustable focus device uses is just over 30mm for two mirrors on tracks with a relatively coarse-thread screw and a manual adjustment knob. The described embodiment of the adjustable focus device isn't automatic and requires manual adjustment. However, it would be possible to motorize the adjustable focus device with minimal difficulty.
Besides material limitations, the solar simulator system with the adjustable focus device depends on an initial proper alignment, a small spot-size for the light source (as is normal for arc-lamps), and that all the reflectors are close to the focal lengths specified (the elliptical reflector for the arc lamp, the beam folding assembly, and the concave mirrors). In addition to this, mirrors should be rated for UV
reflection since those wavelengths are of particular interest for many solar simulator applications.
Although the adjustable focus device does not improve existing uniformity or power output of the solar simulator, it allows the size of the projected uniform field to be adjusted without modifying the remainder of the system. When the adjustable focus device is placed in the beam conditioner of the solar simulator, it provides means to easily and quickly change the focal point of a solar simulator and allows extremely fine-tuned adjustments of the output beam without substantial deviating the uniformity and spectral distribution of the output beam.
Using a 1000W xenon lamp, the housing can generate over 80W of broadband photon power at the focal spot, with 26W-33W in the visible spectrum (400nm-700nm) alone. Such power produces a lot of heat. The exit port is normally covered with a 4.5" diameter quartz window to filter out harmful UVB rays.
However, UVA rays down to 270nm can still go through. If no UV rays are desired, and optional BK7 glass safety window is available to filter out most harmful UV rays below 360nm.
For UV applications, an optional fused silica version which allows all wavelengths including UV light above 200nm to pass through can be used.
An f/2.5 ellipsoidal reflector is employed in this lamp housing. It is made of precision diamond turned solid aluminum piece to bear the exact geometry of an ellipsoidal surface for accurate refocusing of the light from the arc to a small focal point in front of the housing. It is also thermally balanced to assure it does not warp under tremendous heat from the arc lamp as the interior of the lamp housing can reach 200 C. It is also specially coated to reflect all wavelengths ranging from ultraviolet to infrared. To keep the arc lamp housing cooled, a blower at the top draws air from the back of the housing and blows it over the arc lamp, as shown in FIG. 3.
For ozone producing lamps, a water-cooling of the housing must be used such that the ozone can remain inside the arc lamp housing.
The arc lamp housing is designed to work with 500W, 1000W, and 1500W or larger power adjustable power supplied with built-in igniters. These power supplied are highly stabilized switching DC power supplied that can be adjusted above or below its rated power. For example, the 500W power supply can be adjusted between 350W and 600W, the 1000W power supply can be adjusted between 800W and 1200W and the 1500W power supply can be adjusted between 1000W
and 1900W. An optional Optical Feedback Intensity Stabilizer with a built-in fibre optic light sensor can be used to monitor the light intensity of the arc lamp and automatically adjust the power supply to maintain a consistent non-fluctuating intensity. The system uses a fibre-optic cable to sample and direct the arc lamp light to the feedback/computer control unit. The Optical Feedback Intensity Stabilizer is a microprocessor based stand-alone unit which has an external light sensor that monitors the intensity of light and automatically adjusts the power supply upwards or downwards in real time to compensate for any detected intensity fluctuations.
Light proceeds from the ellipsoidal reflector through the beam conditioner system as shown on the FIG. 4. The beam conditioner includes a segmented folding mirror that forms a uniformly illuminated field and a double imaging system that projects an image of the field to the target location.
Light from the elliptical reflector in the arc lamp housing is directed (through the optional water-cooled IR filter) first to a 6-segment mirror assembly.
These segments fold light from different sections of the elliptical reflector face, so that the sections appear to overlap each other, forming a virtual uniformly illuminated field near the position of the ellipsoid face. FIG. 10 shows how two sections from opposite sides of the reflector face can be overlapped, so that the dark region in the 8 center of the face is eliminated, and the decrease in intensity from the insides of the sections to the outsides tends to cancel out. The 6-segment mirror assembly forms three such overlapping pairs on top of each other so light from the entire face of the ellipsoid is used to create the virtual uniform field.
The light then proceeds to a first concave mirror that mirror forms the first real image of the uniform field. The flat mirror directs the beam from the first concave mirror to the output concave mirror which projects the image to a location outside the solar simulator enclosure. The positions of the flat mirror and the output concave mirror can be adjusted with a mechanical linkage that allows the distance of the projected field from the housing to be selected according to the size required for the field. Two stages of imaging are used to provide large field sizes at moderate distances - with only one stage the distance for any particular size of field would need to be much larger.
The beam path carries light through the solar filter (AMO, AM1.0, AM1.5, AM2.0, etc), which is air-cooled by a cooling fan. The solar filters may be replaced while the main sheet metal cover is in place by using the access door at the top of the unit.
An interchangeable reflector mount allows the flat reflector to be replaced by a dichroic mirror (hot/cold mirror) to isolate a specific portion of the spectrum. When a hot/cold mirror is used, heat transmitted from the reflector is drawn away by a water-cooled heat sink behind it.
An optional electronically controlled shutter inside the beam conditioner can be used to control exposure time. An arc lamp is not designed to be frequently turned on and off as a 20,000 V spark is required to ignite it each time. Frequent ignition dramatically lowers the service life of the lamp. That is why for quick exposures, a shutter is recommended rather than switching the Solar simulator light source on and off.
The Beam Conditioner eliminates the necessity for refractive homogenizers, beam diffusers or beam integrators and allows uniform illumination to be obtained with higher efficiency. The beam conditioner system delivers more than 70% of the energy present at the secondary focus of the reflector. The uniformity at the target field is within 10% for the full field size (edge to edge) and 3% over a central area.
The spectral coverage is dependent on the type of arc lamp being used. Since the system is totally reflective (apart from plane parallel windows that do not affect ray directions) there are no chromatic aberrations. Front windows of Pyrex, Quartz or W fused silica can be selected, allowing the unit to be purged for work below 200 nm.
To summarize, the optical system works by using a unique segmented mirror beam-folding arrangement that eliminates the central dark spot usually found with ellipsoid based arc lamp systems, so that the folded ellipsoid face appears to be a very uniformly illuminated field. This virtual uniform field is then projected to a target at a selectable distance and corresponding size outside the housing and size.
A ray trace diagram illustrating the fully reflective design of a solar simulator of the present invention is shown on FIG. 5.
The solar simulator of the present invention, when used with an ozone free xenon arc lamp without any filters, provides a broadband spectral range of 250nm-2500nm.The Air Mass filters and filter combinations allow simulation of various solar conditions, modifying the spectral output of the arc lamp to match specific natural solar conditions (FIG. 6). Some particular filters, shown in the table below, are as follows:
Filter Type Simulated Environment Zenith Angle Air Mass 0 Filter (AMO) Outer Space 00 Air Mass 1.0 Direct Filter Direct solar spectrum on the ground 00 Air Mass 1.5 Direct Filter Direct solar spectrum on the ground 48.2 Air Mass 1.5 Global Filter Global solar spectrum (direct and diffuse) 48.2 on the ground Air Mass 2.0 Direct Filter Direct solar spectrum on the ground 60.10 The AMO filter corrects the output of the arc lamp to simulate the solar spectrum outside of the earth's atmosphere.
The Air Mass 1.0 Direct Filter corrects the output of the arc lamp to simulate the spectrum of the radiation on the ground coming directly from the sun when it is directly overhead (zenith angle 0 ).
The Air Mass 1.5 Direct Filter corrects the output of the arc lamp to simulate the radiation on the ground coming directly from the sun when the zenith angle is 48.2 .
The Air Mass 1.5 Global Filter corrects the output of the arc lamp to simulate the solar spectrum on the ground when the sun is at a zenith angle of 48.2 ;
however the filter also accounts for the diffuse light that is scattered by the atmosphere. As a result, this filter simulates the spectrum of the total radiation, known as global radiation that reaches the ground.
The Air Mass 2.0 Direct Filter corrects the output of the arc lamp to simulate the direct solar radiation at the ground when the sun is at a zenith angle of 60.10.
Filters in the solar simulator of the present invention for air masses larger than AM1.0 were redesigned in such way that they do not need to be used with AMO
and AM1 filters, a technique known as stacking in many prior solar filter designs.
This results in increased transmission efficiency as only one filter is required in the beam path rather than three. This also results in significant cost savings. For example, the previously used AM1.5G filtering is typically the least efficient because it requires other solar filters AMO and AM1 to be placed in front of the 1.5G filter.
After all three filters are placed in series, the previous AM1.5G efficiency is typically less than 40%.
However the stand-alone AM1.5G filter used in the solar simulator of the present invention does not require other solar filters to be stacked with it, resulting in approximately 60% higher throughput.
Additional filtering can be used if the application requires removing the IR
wavelengths longer than 1000nm. There is mounting space inside the solar simulator's beam conditioner unit where an IR water filter (FIG. 7) can be placed to eliminate IR light while preserving UV light, right after the lamp housing and before the first internal mirror, where the beam size is smallest.
The IR absorbing water filter absorbs infrared light between 1000-3000nm.
When filled with 12 distilled water, it absorbs nearly 100% of all IR light in this spectral range while transmitting approx 98% of all visible light between 350nm-700nm. If silica windows are used it also absorbs little UV light between 200nm-350nm, transmitting nearly 80%. This filter has a re-circulated water jacket to cool the filter itself making it excellent for high power applications. The filter body can be made of aluminum or stainless steel. Aluminum is used where only distilled water is to be used. Stainless steel is used when the absorbing media is water, copper sulfate or nickel sulfate.
FIG. 8 and FIG. 9 represent second and third embodiments of the solar simulator of the present invention in horizontal and vertical configurations.
FIG. 8 is basically a side view of the same embodiment as shown on FIG. 1. FIG. 9 is also equivalent to the first embodiment, except that a vertical stand and beam folding output mirror are added to achieve a downward pointing vertical configuration.
The stand and beam folding output mirror enable the fully reflective solar simulator to project its output beam downwards onto a horizontal illumination table, which makes it convenient for solar cell testing. The beam is projected down onto a built-in platform (not shown) where the target sample, such as a solar cell, is placed. With this stand the distance from the output port of the solar simulator to the sample platform can be set to provide 1 SUN intensity (100mW/cm2 using an AM1.5G filter or 136mW/cm2 using an AMO filter); on a 5" diameter target area for a 500W Xe lamp solar simulator, 7" diameter for 1000W Xe lamp solar simulator, 8" diameter for an 1600W Xe lamp solar simulator, or 12" diameter for an 2400W Xe lamp solar simulator.
The invention as described so far uses a unique beam-folding segmented mirror assembly designed to both increase the uniformity of the output while simultaneously not decreasing the power. While this allows us much better input/output power ratios relative to prior art solar simulators, once mirror positions are set the uniform field is projected to a specific location outside the solar simulator body, with a specific size.
Every time a different target size is needed, the plane mirror and the output concave mirror inside the solar simulator that project the uniform field onto the target need to be repositioned. Although this can be performed manually, the procedure is inconvenient should the user need to change the target size frequently. The solar simulator would need to be shut down and have the mirrors re-adjusted to support the new target size. To rectify this situation, an adjustable focus device was developed to easily and quickly change the distance and size of the projected uniform field without need to even open the housing of the system. Two mirrors ride on tracks, attached at fixed angles to maintain the optical path of the system, and are coupled so as to allow a wide range of adjustment to the output beam with a single, simple motion. The system can handle target distances as close as 20cm to a number of meters away without modification, so that the size of the target field can be as small as 3" or as large as wanted. With this adjustable focus device, re-positioning the internal mirrors of the solar simulator is performed through a single lever action, with no need to even shut the solar simulator down. This feature can also be used to vary illumination intensity by spreading the light over a larger area or concentrating the light into a smaller area.
The adjustable focus device itself shown of FIG. 11 is composed of two moving mirrors; a flat metallic mirror, and a concave focusing mirror. The two mirrors are mounted directly to cartridges which slide along flat tracks: the cartridges are slaved to each other (and therefore cannot move independently). It's important that the tracks on which the mirrors slide are aligned parallel to the optical path: the flat mirror slides along the path of the beam coming from the first concave mirror, and the concave output mirror moves along the path of the output beam. The angles of the mirrors do not change.
In order to ensure that the beam reflected from the flat mirror remains centered on the output mirror as the assembly is adjusted, the two mirror mounts are linked by a small metal bar, which is bolted in place on the focus-mirror side but slides freely between two pins on the base of the flat mirror. By this method the two mirrors are slaved together and maintain their proper positions along the optical path.
When the adjustable focus device is installed in the beam conditioner of the solar simulator (FIG. 12) with a specific optical path and the images of the uniform field within the system are at the appropriate places (i.e.: the system has been aligned properly), the device allows the user to project the uniform field over a range of distances along the output beam and corresponding sizes without lengthy alignment procedures. This without any significant lose of energy due to filters or beam homogenizers. While the additional projection optics unquestionably reduce the throughput of the 14 solar simulator by some small amount, the extra loss can be less than 5%.
Solar simulators, due to their highly specialized optics, are normally aligned for a specific target field size at a specific distance from the output of the system (e.g. a 30cm spot at 60cm from the housing). With the adjustable focus device, a much wider range of field sizes can be implemented at various distances with little or no technical knowledge required.
In order to ensure that the solar simulator system with the adjustable focus device operates according to specifications, it is important that the optics (the mirrors in this case) is within design specifications. Specifically, the mirror should be capable of reflecting UV, the accuracy of the focal length in the camera mirror must be high, and the angle at which the tracks are located must be within a few fractions of a degree (otherwise the spot will not be uniform to any useable level). The physical distance the adjustable focus device uses is just over 30mm for two mirrors on tracks with a relatively coarse-thread screw and a manual adjustment knob. The described embodiment of the adjustable focus device isn't automatic and requires manual adjustment. However, it would be possible to motorize the adjustable focus device with minimal difficulty.
Besides material limitations, the solar simulator system with the adjustable focus device depends on an initial proper alignment, a small spot-size for the light source (as is normal for arc-lamps), and that all the reflectors are close to the focal lengths specified (the elliptical reflector for the arc lamp, the beam folding assembly, and the concave mirrors). In addition to this, mirrors should be rated for UV
reflection since those wavelengths are of particular interest for many solar simulator applications.
Although the adjustable focus device does not improve existing uniformity or power output of the solar simulator, it allows the size of the projected uniform field to be adjusted without modifying the remainder of the system. When the adjustable focus device is placed in the beam conditioner of the solar simulator, it provides means to easily and quickly change the focal point of a solar simulator and allows extremely fine-tuned adjustments of the output beam without substantial deviating the uniformity and spectral distribution of the output beam.
Claims (10)
1. A solar simulator, comprising one or more lamps for generating radiation with a spectral distribution that largely corresponds to the spectral distribution of sunlight, lamp power supply, one or more lamp housings with a reflective collector, segmented mirror assembly that creates a uniformly illuminated source field in the beam that emerges from the housing(s), a reflective adjustable imaging device placed following the segmented mirror assembly of the solar simulator, that provides means to project an image of the uniform field and to easily and quickly change the location and corresponding size of the projected uniformly illuminated field and allows a large range field sizes to be selected without substantially deviating the spatial uniformity and spectral distribution at the target field, and air mass solar filters that can adjust the spectrum to simulate the sun's true spectral distribution at various earth conditions.
2. A solar simulator according to claim 1, wherein the radiation source is a single high pressure Xe lamp.
3. A solar simulator according to claim 1, wherein the power supply is an adjustable lamp power supply with optional optical feedback intensity stabilizer and /or computer control of output power.
4. A solar simulator according to claim 1, wherein the reflective collector comprises at least one ellipsoidal reflector.
5. A solar simulator according to claim 1, wherein light from the arc lamp housing(s) is reflected by a 6-segment mirror assembly to an imaging system comprising a first concave mirror, which projects a first image of the uniformly illuminated field, a plane mirror which directs the beam to a second output concave mirror, which projects a second image of the field to a target location outside the solar simulator enclosure, and means to easily and quickly adjust the positions of the mirrors of the double imaging system to easily select the distance of the target location from the solar simulator enclosure and the size of the uniformly illuminated field.
6. A solar simulator according to claim 1 further including a water filter to eliminate infrared radiation.
7. A solar simulator according to claim 1 further including a shutter and means for controlling said shutter so the illumination can be controlled by said shutter.
8. A solar simulator according to claim 1 further including a downward facing vertical stand and beam folding output mirror to achieve a vertical configuration and project the solar simulator's output beam downwards.
9. A solar simulator according to claim 1 in which the adjustable imaging device, positioned after the beam conditioner of the solar simulator providing means to easily and quickly change the distance and size of the uniformly illuminated target field of the solar simulator, includes two movable mirrors whose motions are linked so as to maintain the positioning of the output beam as the distance and size of the field are adjusted.
10.A method to easily and quickly change the focal point of the solar simulator without needing to even open the housing of the solar simulator system.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US94491507P | 2007-06-19 | 2007-06-19 | |
| US60/944,915 | 2007-06-19 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2635287A1 true CA2635287A1 (en) | 2008-12-19 |
Family
ID=40134919
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2635287 Abandoned CA2635287A1 (en) | 2007-06-19 | 2008-06-18 | Fully reflective, adjustable field size illuminator for solar simulation |
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| Country | Link |
|---|---|
| CA (1) | CA2635287A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109036009A (en) * | 2018-01-19 | 2018-12-18 | 北京市遥感信息研究所 | A kind of spatial remotely sensed imaging semi-physical simulation platform based on the tilting mode of sand table |
-
2008
- 2008-06-18 CA CA 2635287 patent/CA2635287A1/en not_active Abandoned
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109036009A (en) * | 2018-01-19 | 2018-12-18 | 北京市遥感信息研究所 | A kind of spatial remotely sensed imaging semi-physical simulation platform based on the tilting mode of sand table |
| CN109036009B (en) * | 2018-01-19 | 2023-10-17 | 北京市遥感信息研究所 | Space remote sensing imaging semi-physical simulation platform based on sand table inclined mode |
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