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PlaneWave Instruments IR DK17 17 inch Infrared Dall-Kirkham Optical Tube Assembly

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Product Description

This is a Dall-Kirkham optical design with coatings that are optimized to transmit in infrared 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.  The reflectives coatings are a protected gold which give better than 98% reflectivity from .65 micron (650nm) to 16 micron (16000nm).  This design is ideal for infrared astronomy or LIDAR applications.   The IR DK is available in the three different apertures, 20", 17" and 12.5" 


Aperture  17"
Focal Length  2939 mm
Focal ratio  f/6.8
Central Obstruction  39%
Back Focus  8.8" from focuser mounting surface, 5.8" from racked in focuser
Weight  94 lbs
OTA Length   37" 
Upper Cage  Carbon Fiber Truss 
Lower Cage  Carbon Fiber Truss with Carbon Fiber light shroud

Primary Mirror

Diameter 17.75"
Aperture 17"
Focal ratio f/2.6
Mounting Laser Collimated and Permanentely Fixed 
Material Precision Annealed Pyrex
Shape Prolate Ellipsoid
Coating Protected Gold Reflective Coating - 98% (.65-16micron)

Secondary Mirror

Diameter 6.25"
Material Precision Annealed Pyrex
Shape Spherical
Coating Protected Gold Reflective Coating - 98% (.65-16micron)

Standard Features

Carbon Fiber Tube Design Minimizes thermal expansion which causes focus shift with changes in temperature
Carbon Fiber Lower Light Shroud Protects the primary mirror from damge and from stray light.
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
3.5” Hedrick Focuser Heavy duty no-slip focuser.  The focus tube runs on 5 bearings and is driven by a leadscrew so there is no chance of slipping.  It accepts an optional dial indicator and PlaneWave’s EFA Kit to control many electronic accessories.  The draw tube travel is 1.3". 
 Colling Fans Three fans blow out of the optical tube pulling air though the telescope and by the primary mirror. This helps the telescope to equilibrate quickly.  The fans are controlled by a switch on the optical tube or can be controlled by a computer if the optional Electronic Focus Accessory (the EFA Kit) is purchased.

Shipping Dimensions and Weight  

Crate Dimensions:  45" x 29" x 33"

Crate Shipping Weight:  225 lbs

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