PlaneWave DK 望遠鏡 CDK 12.5"-24" CDK700 -----(2)

文章由 **Wongsir** » 週四 08 4月, 2010 18:19

PlaneWave DK 望遠鏡 CDK 12.5"-24" CDK700

The CDK Optical Design
The CDK [Corrected Dall-Kirkham] telescope is based on a new optical design developed by Dave Rowe. The goal of the
design is to make an affordable astrographic telescope with a large enough imaging plane to take advantage of the large
format CCD cameras of today. Most telescope images degrade as you move off-axis from either coma, off-axis astigmatism,
or field curvature. The CDK design suffers from none of these problems. The CDK is coma free, has no off-axis astigmatism,
and has a flat field. The design is a simple and elegant solution to the problems posed above.
The CDK consists of three components:
an ellipsoidal primary mirror, a spherical secondary mirror and a lens group.
All these components are optimized to work in concert in order to create superb pinpoint stars across the entire 52mm

Price:
CDK12.5" US$9,900 OTA ( 2010' )
CDK17" US$22,000 OTA
CDK20" US$32,000 OTA
CDK24" US$50,000 OTA
CDK700 US$185,000 Telescope system

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FEATURES AND SPECIFICATIONS

SYSTEM
Aperture 24 inch (610 mm)
Focal Length 4145 mm (163.19 inch)
Focal Ratio f/6.8
Central Obstruction 41% of the Primary Mirror Diameter
Back Focus from Mounting Surface 13.22 inch (336 mm)
Back Focus from Racked in Focuser 10.81 inch (275 mm)
Weight 240 lbs (109 kg)
OTA Length 55 inch (1,397 mm)
OTA Width 32 inch (813 mm)
OTA Height 37 inch (940 mm)
Upper Cage Carbon Fiber Truss
Lower Cage Carbon Fiber Truss with Carbon Fiber Light Shroud
Optimal Field of View 70 mm (58 arcminute)

PRIMARY MIRROR
Diameter 24.5 inch (622 mm)
Aperture 24 inch (610 mm)
Focal Ratio f/3
Mounting Laser Collimated and Permanently Fixed
Material Precision Annealed Borosilicate
Shape Prolate Ellipsoid
Coating Enhanced Aluminum - 96%

SECONDARY MIRROR
Diameter 9.45 inch (240 mm)
Material Precision Annealed Borosilicate
Shape Spherical
Coating Enhanced Aluminum - 96%

LENS GROUP
Diameter 105 mm (4.13 inch)
Number of lenses 2
Coating Broadband AR Coatings (less than .5% reflected from 400 to 700nm)

STANDARD FEATURES
Carbon Fiber Truss Design Minimizes thermal expansion which causes focus shift with changes in temperature
Lower Light Shroud Protects the primary mirror from damage and 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 inch 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 inch.
Image 1
Image 2
Drawing of Flange
Drawing of Draw Tube
Cooling Fans The CDK24 has two different cooling schemes. First there are three fans behind the primary mirror that blow air out of the optical tube pulling air though the telescope and by the primary mirror. This helps the telescope to equilibrate quickly. The second scheme is that there are 8 fans placed around the face of the primary mirror to equilibrate the face of the mirror and to keep a laminar air flow above the telescope's light path. The two schemes can be controlled separately with the included switches on the optical tube or can be controlled by a computer if the optional Electronic Focus Accessory (EFA Kit) is purchased.

INCLUDED ACCESSORIES
3.5" to 2" Adapter (200349) Adapts the 3.5" inner diameter of the focuser to a standard 2" inner diameter. This adapter is necessary when setting the primary to secondary spacing. The 200399 Visual 3.5" to 2" adapter is an optional accessory that is designed to space a 2" diagonal for visual use.
Rochi Spacer (200354) This spacer is used for setting the primary to secondary spacing. It has an 1-1/4 inner diameter and may be used with 1-1/4 oculars for collimation.
Rochi Ocular This ocular is a Ronchi screen used for setting the primary to secondary spacing.
Primary Mirror Cover he OTA cover is for closing the front of the tube to protect the primary mirror and the inside of the optical tube.
Printed Instructions For Collimation and Spacing
12VDC Power Supply (18778) Provides power for the fans (Not included for European Orders)
Wrench Set (5812A35) English Hex Wrenches (European Orders Only)