PlaneWave IRDK 24" DAll-Kirkham
This is a Dall-Kirkham optical design with coatings that are optimized to transmit in infrared or ultra violet wavelengths. It is diffraction limited across a 20mm image circle at the focal plane. There are no refractive lens, only reflective components to the design. For IR application, reflectives coatings are a protected gold which give better than 98% reflectivity from .65 micron (650nm) to 5 micron (5000nm). This design is ideal for infrared astronomy or LIDAR applications. UV optimized coatings can also be used at an additional cost.
The DK is available in the three different apertures 12.5 ", 20", 24" and 28".
The PlaneWave IRDK 24 is available in various types of mirror material. Standard mirror material is borosilicate. The telescope is also available in fused silica optics.
Fused Silicia is a synthetic amorphous silica glass of the highest purity and one of the most transparent glasses made. The optical and thermal properties of fused silica are superior to other types of glass due to its purity. Its transmission and homogeneity exceed those of crystalline quartz without the problems of temperature instability inherent in the crystalline form. Fused Silica has a coefficient of thermal expansion six times lower than Borosilicate (Pyrex) glass, which means that as fused silica cools down, it preserves its shape to a high degree of accuracy. This translates into consistent optical performance and unchanging focus over temperature changes. With its high melting temperature ()~ 1.600 degree Celsius), a very low coefficient of thermal expansion and resistance to thermal shock, fused silica is the material of choice for professional observatories as well as various scientific applications.
Aperture 24 inch (610 mm) Focal Length 3962 mm (155.98 inch) Focal ratio f/6.5 Central Obstruction 47% of the Primary Mirror Diameter Back Focus from Mounting Surface 14.1 inch (358 mm) Back Focus from Racked in Focuser 5.81 inch (148 mm) Weight 240 lbs (108.9 kg) OTA Length 56 inch (1,422 mm) UpperCage Carbon Fiber Truss Lower Cage Carbon Fiber Truss with Aluminum Light Shroud OTA Width 31 inch (787 mm) OTA Height 35 inch (889 mm) Optimal Field of View 70mm Image Circle
Diameter 9.45 inch (240 mm) Material Precision Annealed Borosilicate or Fused Silica Shape Spherical Coating IR or UV optimized
Aperture 24 inch (610 mm) Diameter 24.5 inch (622 mm) Focal ratio f/3.2 Shape Prolate Ellipsoid Material Precision Annealed Borosilicate or Fused Silica Coating IR or UV optimized
Carbon Fiber Tube Design Minimizes thermal expansion which causes focus shift with changes in temperature Dovetail expansion joint Allows for the difference in thermal expansion between carbon fiber and aluminum. The expansion joint allows the aluminum dovetail expand and contract without stressing the carbon fiber lower truss Cooling Fans Three cooling fans blow air inside the back of the telescope. This helps the telescope to reach thermal equilibrium quickly. The fans are controlled by a computer if the optional Electronic Focus Accessory (EFA Kit) is purchased.
|Back Focus Distance||14.1" (358 mm) from Mounting Surface, 5.81" (148 mm) from Racked in Focuser|
|Aperture (mm)||24" (610 mm)|
|Focal Length||3.962 mm (155.98 inch)|
|Image Field||70 mm|
|Central Obstruction||47% of the Primary Mirror Diameter|
|Optical tube length||55,98 inch (1.422 mm)|
|Optical Tube Weight Copy||240 lbs (109 kg)|