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IRDK20 (Infrared Optimized)

SKU# 200120Q

Price: $37,500.00


*Price is based on PlaneWave’s Pricing Policy

The IRDK20 is a 20-inch infrared-optimized optical tube designed for research applications where on-axis performance is crucial.

  • Dall-Kirkham optical design
  • Focal length of 3,454 mm (f/6.8)
  • Mirror coatings that are optimized to transmit in infrared wavelengths (ultraviolet optimization available)
  • Fused silica mirrors with low thermal expansion
  • Ready for Delta-T dew prevention


This is a Dall-Kirkham optical design with coatings that are optimized to transmit in infrared wavelengths. There are no refractive lenses, only reflective components to the design. For IR application, reflective coatings are a protected gold that gives 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 be provided as well, so please reach out to our technical sales team to discuss UV optimization.

  • IRDK20 is a 20 inch infrared optimized optical tube with fused silica mirrors
  • Focal length of 3,454 mm (f/6.8)
  • Dall-Kirkham optical design with coatings that are optimized to transmit in infrared wavelengths (ultraviolet optimization available)
  • Ready for Delta-T dew prevention


IRDK 20 Features

Carbon Fiber Truss Design


Minimizes thermal expansion which causes focus shift as temperature changes during an imaging session. Carbon fiber also reaches ambient temperatures quickly and is extremely lightweight and rigid to help ensure excellent imaging data is produced.

3D Printed Baffles


PlaneWave uses digital 3D printing technology to produce lightweight baffle tubes. 3D printers add successive layers of material to construct a baffle system with precision positioned internal stray light baffles to minimize vignetting and maximize image contrast. Quality baffling makes an incredible difference in overall image quality, so we ensured an optimal design was created for our telescopes.

Dovetail Expansion Joint


Allows for the difference in thermal expansion between carbon fiber and aluminum. The expansion joint allows the aluminum dovetail to expand and contract without stressing the carbon fiber lower truss. This results in images that are not distorted due to expansion, or contraction of the optical tube materials.

Delta-T Ready


For added dew prevention, the CDK20 is internally wired with polyimide film heater pads and temperature sensor, which is ready to be controlled with the Delta-T via PlaneWave Interface 3 software.

Cooling Fans


Three fans on the backplate of the optical tube pull air through the telescope and by the primary mirror. Three fans on the side of the optical tube also blow air across the primary to ensure a boundary layer of air does not distort images. These fans help the telescope reach thermal equilibrium quickly, further reducing any distortion in images due to temperature variations. The fans are controlled by a switch on the optical tube, or can be controlled by via PWI3 software if a PlaneWave Electronic Focus Accessory (EFA Kit) is purchased.



Optical System

Aperture 20 inch (508 mm)
Focal Length 3454 mm (136 in)
Focal ratio F/6.8
Central Obstruction 39% of the Primary Mirror Diameter
Back Focus from mounting surface 8.81 inch (224 mm)
Weight 140 lbs (63.5 kg)
OTA Length 47 inch (1,194 mm)
Upper Cage Carbon fiber truss
Lower Cage Carbon fiber truss with carbon fiber light shroud
Optimal Field of View 52mm image circle

Secondary Mirror

Diameter 7.5 inch (191mm)
Material Fused silica (quartz)
Shape Spherical
Coating Gold Protected

Primary Mirror

Optical Diameter 20 inch (508 mm)
Outer Diameter 20.5 inch (521 mm)
Shape Prolate ellipsoid
Material Fused silica (quartz)
Coating Gold Protected


Crated Shipping Weight 291 lbs   (132.0 kg)
Crate Width 33 inch   (838 mm)
Crate Height 33 inch   (838 mm)
Crate Length 65 inch   (1,651 mm)

Included Accessories

Included Accessories

Primary Mirror Cover To protect the primary mirror
PlaneWave Thumb Drive Contains software and instructions for collimation and spacing the primary to secondary mirror
12VDC Power Supply Provides power for the fans (Not included for European Orders)
Wrench Set
Standard hex wrenches (European orders only)





For warranty information please check our Standard Warranty Page.