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Adjusting collimation of the CDK700 Telescope
Applies to CDK700 telescopes sold after January 2013.
Introduction
In order to fully collimate the CDK700, the following steps are required:
1. Align the laser to be perpendicular to the laser adapter plate.
2. Align the secondary mirror relative to the backplate of the telescope.
3. Check the height of the M3 (diagonal) mirror
4. Align the M3 (diagonal) mirror relative to Port 1
5. Align the M3 (diagonal) mirror relative to Port 2, if applicable
6. Align the Primary mirror
Step 1 – Align the laser to be perpendicular to the laser adapter plate
PlaneWave CDK700 telescopes typically ship with a laser that can be inserted into a 1.25" or 2"
diameter eyepiece tube. This tube is attached to a plate that can be secured to the two Nasmyth
ports on the side of the telescope, and to a port on the backplate of the telescope.
To produce the most accurate collimation and to simplify later steps of the collimation process,
the laser must be aligned to be perpendicular to the adapter plate. A misaligned laser will trace
a circle if you spin the plate in the port, as shown below. If the laser is well aligned, the spot will
remain in the same place as you rotate the adapter.
0°
270°
True center
180°
0°
Side view: spinning the adapter causes a
180°
misaligned laser beam to trace a cone
Front view: spinning the adapter causes a
90°
misaligned laser spot to trace a circle
1
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Related Manuals for PlaneWave Instruments CDK700
Summary of Contents for PlaneWave Instruments CDK700
- Page 1 Step 1 – Align the laser to be perpendicular to the laser adapter plate PlaneWave CDK700 telescopes typically ship with a laser that can be inserted into a 1.25” or 2” diameter eyepiece tube. This tube is attached to a plate that can be secured to the two Nasmyth ports on the side of the telescope, and to a port on the backplate of the telescope.
- Page 2 One suggested procedure for aligning the laser is described below. A. Remove all equipment (including the IRF90 Rotating Focuser) from either Port 1 or Port 2 of the telescope. Insert the laser into the collimation adapter, and insert the adapter into the port.
- Page 3 E. Securely tape a piece of paper to the wall or dome so that the spot is shining on the paper. F. Loosen the 3 laser adapter retaining ring screws , rotate the adapter to a position that is easy to identify (such as the one shown below, with one knob pointed left and the other knob pointed up), and tighten the screws again.
- Page 4 A summary of the alignment steps is included below; if you have any questions, please contact PlaneWave Instruments. A. Tilt the telescope down towards the horizon. On the backplate of the telescope, locate the central cover (typically held in place with 4 screws and 4 spacers).
- Page 5 of the telescope will be removed. Reach inside the telescope and unplug the two fans. One option is to slide a small white connector off the body of the fan, and unhook the wires from the edge of the fan if necessary. Another option is to locate the Molex connectors near the edge of the primary mirror and unplug the fans at this location.
- Page 6 M. Attached the aligned laser adapter to the port on the back of the telescope, and secure it using the retaining ring and 3 screws. Turn on the laser. If some of the loose M3 wires are in the way of the laser beam, push them to the side. N.
- Page 7 This alignment is performed at the factory and normally should not need to be adjusted. If you determine that some adjustment is necessary after working through the steps below, contact PlaneWave Instruments for details. If you wish to verify the height of the M3 mirror: A.
- Page 8 4. Turn on the laser. In a perfectly collimated system, the beam would hit M3, reflect up to the center spot on the secondary mirror, reflect back down to the same spot on M3, and back over to the laser installed in Port 1. In an imperfectly collimated system, the beam will diverge after it bounces off the secondary mirror.
- Page 9 Poor alignment. Need to tilt the Better alignment. Spin laser adapter to mirror down confirm true centering. Remember to align the laser before doing this. If the laser is not perfectly aligned with the adapter plate (as described earlier), you can rotate the adapter to different positions, locking down the retaining ring at each position.
- Page 10 Hardstop block Hardstop screw Set screw The tilt adjustment is performed by releasing a jam nut and loosening/tightening a hardstop screw that the hardstop pin runs against. A set of magnets either repel each other, tilting the mirror up (for one port) or attract each other, tilting the mirror down (for the other port).
- Page 11 Each port can be adjusted independently Magnets attract or repel to tilt the mirror in different directions When the tilt alignment is correct, tighten the jam nut back into place, being careful to not turn the hardstop screw away from its aligned position. You may need to back off the hardstop screw a bit before tightening the jam nut.
- Page 12 in the optical system. It may be necessary to align the secondary mirror -- refer to the secondary mirror alignment instructions above. 6. Using the PlaneWave Interface software, move the M3 mirror to Port 2. After a few seconds, click "STOP", and then move it back to the Port 1 position. Use the laser to verify that M3 has returned to the correct position and is repeatable.
- Page 13 Between the bottom surface of the primary baffle tube and the top surface of the primary mirror, there is a threaded retaining ring that prevents the mirror from moving forward. Loosen this ring 1-2 turns by turning it in the counter-clockwise direction. With the side panels installed on the telescope you may not be able to see this ring directly, so you will need to feel under the M3 mechanism to find the ring.
- Page 14 NOTE: On some telescopes, each of these adjustment screws is surrounded by up to three smaller locking screws. It may be necessary to loosen these locking screws before adjusting the primary. These should be re-tightened once any adjustments have been completed. Tip/tilt screw Locking screws The goal is to tilt the mirror so that the star moves in the same direction as the thick portion of...
- Page 15 To determine the correct screw to turn, place your arm in the optical path of the telescope to block some of the incoming starlight. (e.g. reach in from the side of the telescope and touch the edge of the primary baffle with your fingertips.) This will cast a shadow and cause the defocused star to appear as shown below: Shadow cast by arm If you don’t see a shadow, you may need to use something wider to block the light, such as a...
- Page 16 Direction of movement when turning screw “A” either clockwise or counterclockwise Try turning this screw either clockwise or counterclockwise, and take note of which direction the star moves. Turn the screw so that the star moves in the same direction as the thickest part of the defocused disc.
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