PlaneWave PW1000 1-Metre Observatory Telescope

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POA
SKU 1323300Q
  • Huge 1-metre aperture class instrument featuring fused silica optics
  • Dual Nasmyth focus ports, allowing simultaneous mounting of two instruments and easy switching between imaging  and visual use.
  • Pinpoint stars over a 100mm image circle (1 degree)
  • Integrated field de-rotator
  • Integrated primary mirror shutter cover
  • Direct-drive motors on each axis for smooth, fast, and virtually silent movement of the telescope
  • High-resolution absolute encoders on each axis for precise positioning
  • Zero backlash and zero periodic error
  • PointXP mount modeling software
Introduction

One metre class telescopes were until recently specialist custom made instruments. Now, PlaneWave Instruments are proud to announce their PW1000 - a complete 1-metre observatory-class telescope that features their direct drive altitude-azimuth (Alt-Az) mounting system.

The PlaneWave PW1000 uses a Corrected Dall-Kirkham (CDK) optical design, made from in-house light-weighted zero expansion fused silica materials for excellent thermal stability diffraction-limited. With a 100mm image circle, the PW1000 is designed to excel at imaging on the largest format CCD cameras available today. The telescope features dual Nasmyth ports allow two instruments to be installed simultaneously, and a computer-controlled M3 mirror allows either instrument to be remotely selected in seconds. The PW1000 mount features direct drive motors with high resolution encoders resulting in zero backlash and no periodic error. 

The PW1000 uses the same proven technology as the CDK700.  Many CDK700s are deployed around the world at various institutions including the University of Central Lanchashire's Alston Observatory in England (see >>here<<) 

The PW1000 sets a new standard in 1-meter class observatory telescopes.

Below is a video by PlaneWave of a PW1000 telescope being installed at the Seoul National University in South Korea. This video shows the size of each of the components and the relative ease of how the telescope is assembled.

Optical Design 

The PlaneWave PW1000 employs a corrected Dall-Kirkham (CDK) Optical Design. This is a new innovative optical solution, developed by Dave Rowe, for unsurpassed scientific investigation, visual observing and astro-imaging at an affordable price. It has excellent performance with large format CCD cameras, far exceeding the off-axis performance of most commercial telescope designs, including the uncorrected Ritchey-Chrétien (RC).

Most telescope images degrade as you move off-axis from either coma, off-axis astigmatism, or field curvature. The CDK optical design is a simple and elegant solution and suffers from none of these problems. The CDK

  • is coma free,
  • has no off-axis astigmatism,
  • has a flat field. 

The CDK optical system consists of three components: an ellipsoidal primary mirror, a spherical secondary mirror and a lens group. All these components are optimised to work together in order to create superb pinpoint stars across an entire 52 to 70mm image plane.

To the right are two diagrams showing the CDK's stunning performance. The one on the left is a spot diagram for the 1-metre/40" CDK optics on the optical axis, 35mm- and 50 mm off-axis. The one on the right is a diffraction simulation.  The diagram on the right shows the image quality and the vignetting of the 100mm field of view of the CDK 1000.

 

The CDK design produces a flat, coma-free and astigmatic-free field of view. Since the secondary mirror is spherical, centering is very forgiving, making it easy to align the telescope optics for optimum performance. The end result at the image plane is no off-axis coma, no off-axis astigmatism, and a perfectly flat field to the edge over a 100mm image circle.  The stars will be pinpoints from the center to the corner of the field of view. With a diffraction-limited image circle size of 100mm diameter, the PW1000 is designed to excel at imaging on the largest format CCD cameras available today. 

Telescope Features

Light-weighted optics are made of zero expansion fused silica materials for excellent thermal stability and maximum throughput. Fused Silica which has a coefficient of thermal expansion six times lower than Borosilicate (Pyrex) glass. This means that as the mirror cools down, fused silica preserves the mirror's shape to a high degree of accuracy resulting in a consistent optical performance and unchanging focus over wide temperature changes.

 
Photograph of the lightweighted 1-metre primary mirror of the PW1000

 The telescope features dual Nasmyth ports that allow two separate instruments to be installed on either side of the telescope's mount. A computer-controlled tertiary (M3) mirror allows either instrument to be remotely selected in about 10 seconds.  

The PW1000 telescope features a dual Nasmyth focus. These two focus positions are along the telescope's altitude axis so that the telescope mount does not need to be re-balanced when changing or adding equipment. If you are going to use the telescope for visual use, the eyepieces remain at a constant height, greatly simplifying access to the telescope for public observatories.

Diagram showing the Nasymth focus positions of the PW-1000 Telescope 

 

The PW1000 includes an integrated computer controlled rotating tertiary mirror (M3) which incorporates magnetic locks to position the mirror precisely at either Nasmyth focus position. The rotator can move from one port to the other in under 10 seconds, allowing observers to quickly easily transition between imaging and visual use, or other instrumentation such as spectroscopy.

  Photograph of the Tertiary Mirror M3 of the PlaneWave PW1000.
Mount Features

Altitude-Azimuth (Alt-Az) mounts are the choice for most modern professional observatories as they are inherently more stable than an equatorial mount. This is because there is no cantilevered mass, nor are there any large protruding counterweights to create a dangerous hazard in a public observatory.

An Alt-Az telescope is also considerably more compact than its equatorial counterpart, allowing a larger telescope to fit in a smaller observatory enclosure. The mass required to make a rigid Alt-Az mount is substantially less, leading to substantial cost savings.

When it comes to tracking celestial objects, unlike German Equatorial mounts, there are no meridian flips to deal with and therefore you can image continuously from horizon to horizon if desired. With no polar alignment required, the Alt-Az mount is far more intuitive to use than a German Equatorial mount.

Direct Drive motors and absolute on-axis encoders eliminate the need for reduction gears, thereby eliminating backlash and periodic error. With high-resolution encoders providing feedback for the direct drive motors, not only will the telescope track without periodic error and backlash, the mount will also counter wind gusts with precise servo feedback. The direct drive motors can move the telescope at incredible speeds of up to for tracking satellites or just to minimize target acquisition time.

Direct Drive Magnets Direct Drive Magnets with Coils

 

 
Photograph showing the altitude direct drive mount for the PW1000

An integrated and automated primary mirror shutter protects the 1-metre primary mirror from unwanted dust and moisture. The four shutter system is fully controllable with PlaneWave's PWI software.

 
Diagram showing the 4-leaf primary shutter cover
Specifications

OPTICAL SYSTEM

Optical Design Corrected Dall-Kirkham (CDK)
Aperture 1000 mm (39.37inch)
Focal Length 6000 mm
Focal ratio f/6
Central Obstruction 47% of the Primary Mirror Diameter
Back Focus 373mm (14.7 inches) from Mounting Surface of de-rotator
Weight 2600 lbs
Optical Tube Dual truss structure with Nasmyth focus ports
Optical Performance 3.7 micron RMS spots [35mm on-axis] (400 to 900nm) 5.0 micron RMS spots [50mm off-axis] (400 to 900nm) Spot Diagram Vignetting Diagram
Dimensions 135" H x 72" W x 45"
Optimal Field of View 100mm (1.0 degrees)
Focus Position Dual Nasmyth Focus Ports
Image Scale 29 microns per arcsecond at F/6

 

 

MECHANICAL STRUCTURE

Fork Assembly Space Frame Steel Truss
Fork Base Welded stainless steel torsion box
Azimuth Bearing Dual 11.125 inch tapered roller bearings
Altitude Bearing Three 9.5 inch 4 way loaded ball bearings (two pre-loaded on motor side and one on non motor side)
Optical Tube Dual truss structure with Nasmyth focus
Instrument Payload 300 lbs (150 ft-lbs) - mounted on the field de-rotator plate

 

MOTION CONTROL

Motor Control Industrial grade Parker brushless motor control system and built in electronics
Motor - Azimuth and Altitude Direct Drive 3 Phase Axial-Flux Torque Motor
Encoder - Azimuth and Altitude Absolute encoder with a resolution of 0.078 arcseconds (16.5 million counts per revolution)
Motor Torque Greater than 200 ft-lbs of peak torque
Drive Electronics Controls the altitude and azimuth motors and encoders, 2 direct drive de-rotators with absolute encoders, 4 fans zones, 3 dew heater zones, two focusers, an array of temperature sensors, M3 port selector, primary mirror covers and magnetic axis deceleration
Telescope Control Software Incorporates PointXP mount modeling software and All Sky PlateSolve both by Dave Rowe. Also included is automatic focusing, dew heater control, primary mirror cover control, dome control and all ASCOM compatible. Linux and Windows compatible.

 

SYSTEM PERFORMANCE

Pointing Accuracy Better than 10 arcsecond RMS with PointXP Model
Pointing Precision 2 arcsecond
Tracking Accuracy <1 arcsecond error over 10 minute period
System Natural Frequency 10 Hz or greater
Field De-Rotator Accuracy < 3 microns of peak to peak error at 35mm off-axis over 1 hour of tracking (18 arc sec)

 

PRIMARY MIRROR

Radius of Curvature 6260 mm (246.46 inches)
Optical Diameter 1000 mm (39.4 inch)
Outer Diameter 1020mm (40.157inch)
Core Diameter 360.7 mm (14.2 inches)
Material Fused Silica
Primary Thickness 85 mm (3.3 inches)
Primary Weight 122 lbs. (54% light weighted)
Cell 18 point

 

SECONDARY MIRROR

Radius of curvature 5740 mm (226 inches)
Optical Diameter 450 mm (17.7 inches)
Material Fused Silica
Secondary Weight 27.2 lbs

 

TERTIARY MIRROR

Optical Major Diameter 404 mm (15.9 inches)
Optical Minor Diameter 286 mm (11.3 inches)
Material Fused Silica
M3 Thickness 65 mm (2.6 inches)
Downloads

PW1000 Telescope Dimensions PDF HERE

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