IOTA - ALIGNMENT
IOTA Alignment with Integrated Optic Combiner:
New Remote Method
beam-
splitter dichro
to ccd ----------/----------------/---{---------- to telescopes
| / {--> retro
| /
Al Camera fiber
The alignment system for the IOTA is now done remotely -
almost everything is done from the computer terminal
and only a couple of steps require that the observer go into the observation area.
components
1) camera, beam splitter, slider, software to look through system.
2) AAIB - Auto Align Interface Box
3) MC panels
________Control: Al paddle
________Monitor: Al Cam
The slider for the alignment is controlled from the Dell Windows computer
Log in as Observer
Password is _ _ _ _ _ _ _ _ _
The program to start is EZStepper3 - on the desktop, lower left
After the program starts you should hit the Load Strings button to get the commands
The file to load is EZStepper/allmot3
hit open after selecting the file name in the window.
The commands are
/1V1500R-----------Set the speed - if the speed is not reset the motor tries
to move too fast and nothing happens.
/1Z4000V1500R---Move 60000 steps toward home and reset speed.
The home action unsets the speed.
/1A18990R----------Move to location 18990 - the D2 beam position
/1A38990R----------Move to location 38990 the D1 beam position
/1A58990R----------Move to location 58990 the fixed beam position
/1A0R-----------------Move the Home position
/1?0--------------------Report the location of the slider
can be checked during motion
/1z39070R-----------Index the position to 39070 - useful after power down
When hitting most commands the string "No Error" should appear in the reply space.
The motor controller must be turned on for software to work.
The motor, camera, and monitor are controlled from above the command console.
****If you power down the system it will forget the speed and location,
you will need to index the position, set the speed, move to zero and then home.
Homing also erases the speed setting so the home string resets it.
If you overshoot in either direction there is a limit switch which powers the
motor & controller down.
Removing the spacer block will let you command the motor away from the limit
then the spacer block should be reinserted.
The camera focus is controlled from a box at the command console.
It can be controlled through the interface but switching commanded motors
seemed somewhat cumbersome and some of the focus changes require many second motions.
The AAIB box must be powered up to control the alignment lights and motors.
The box actuates all the Flip in lights and the DC motors. The picomotors are
controlled through two serial connections to the VME.
(They do not need to be on at boot-up however). The AAIB also
can command the PICNIC filterwheels motor problems and electrical incompatibilities
have made this operation inconsistent.
The AlPaddle control panel is how the motors and lights are enabled.
At the top are menu items to
a) Select the light - Exit, SD, LD, Corner, Feed Piezo, Secondary
b) Select the DC motor you want to move - LD, Feed, Piezo block
------you can select the duration (0.05 sec to 2 seconds)
------you can select the direction (up, down, left, right)
c) Select the Picomotor you want to move
- AlCam, Exit, SD, Corner, C Feed, Fiber,
------you can select the number of pulses
(50 is a good number for small steps)
------you can select the direction (up, down, left, right)
The Alignment Camera Monitor will display the image from the camera.
Left click in the window to grab a new frame (sometimes it takes 2 clicks).
You can get the centroid for an image by drawing a box around the spot
holding down the left mouse button and then clicking in the box with the
right mouse button. The numbers are presented at the upper right of the screen.
You should follow the sequence given on the Alignment sheet posted at the
console to align IOTA.
The coordinates change from light to light because the focus axis of
the lens is not straight.
Sequence of steps
1) start up systems
2) move Al Beamsplitter to the beam you want to align first
3) Flip up exit light
4) Focus the image on the left TV monitor
5) Grab a frame by clicking in the Al Cam Monitor window
6) Get the centroid
7) Select the Al Cam Picomotor
8) Move the spot until it is on the correct pixel (+/- 1 pixel)
9) Flip down the exit light
10) Turn on the SD light (or Corner if you are on Fixed)
11) Focus the camera
12) . . .
13) Continue until the fiber has been centered
(you still manually put in the retros)
14) After the fiber is centered on the Al Camera you can center it on the
Star Tracker
15) Move the image with the Star Tracker Picomotors
(don't have the scale yet)
Notes -
You can still manually adjust the picomotors but you need to press the "Local"
button or cycle power on the unit before it will respond to the paddle.
This may be the best way to get the fiber on the Star Tracker when
it is way off.
You can leave the Beamsplitter in place for bright stars
and take the 50% hit on the star tracker.
This lets you look at the out of focus star image easily.
There does not seem to be any deflection of the beam associated with
the beamsplitter.
Turning on the LD light moves the LD yaw so be careful about it or you
will mess up your alignment.
You now do the yaw correction from the console.
Before moving the long delay, you adjust the Al Beamsplitter to put the spot
on the correct coordinate and, after moving the long delay to its new position, you move the spot back to the correct coordinate with the LD Yaw.
The electronics for Yaw don't react as fast as the computer. Commanding
LD2 Yaw often results in some motion in LD1 Yaw so do LD2 first and then
LD1 after changing the LD positions.
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