The Mad Invention thread ..

[NickK]

Well the idea of this thread is to propose problems primary... then people can comment ideas on ways to solve the problem - be it technical, software or just observations.

I have a couple of ideas I'm thinking around (for some time):

1. Passive deconvolution (software) using realtime full frame guiding to model the churn of the atmosphere. The result is that the image frame is then post processed with the information - resulting in a sharper image. Not as good as a massive laser with a wavefront detector and a deformable voicecoil mirror but should be a good intermediate step. I'm progressing on this one..

To illustrate - here's a guide star over time..

1a ) solar deconv by using motion tracking on each frame. I have optic flow already on this, for example here's a sunspot showing the atmosphere churn:

2. Accurate encoders using light interference - using toy fibre optics, a test has shown that it's possible to take a single red laser light down a known length fibre optic and a shine the same light down a fibre stuck to a circumference of a scope mount. The image and interference pattern can then be captured on a CCD. The combination of medium resolution normal means and this allows for very very accurate positioning. The main issue is that it also measures any play in the bearing (which is good)

This could be countered by watching the interference pattern reflected by the shaft - if it changes then the shaft is moving out of alignment.

This is the CCD image showing the output from the two fibre alignment:

It would be possible to refine this in software to detect the change over movement and then relate that to position.

3. Accurate shaft positioning ... magnetic flux bearings.. this would allow the bearing to keep central to a very high accuracy. A magnetic lazy susan would be really useful..

4. Direct drive axis movement .. this one I'm also looking at as I want to create my own DD mount at some point.. 

http://starryridge.com/telescopes/index.php?title=Direct_Drive_Motors

5. Direct drive focuser .. well as you can position really really accurately.. why not put magnets to the focuser tube and then use magnetic flux to keep them in position? If you use a tri-pole design with three direct drive actuators (using point 3).. you could also ensure that there's no focuser sag by varying the flux field strength in each actuator.

You could mount a plate with three magnets on and use voice coils to apply pressure to adjust manual focuser sag..

[ronin]

The problem of (1) would seem to be that you need to first measure the churn of the atmosphere in order to process it and remove it. Knowing there is some, is different to knowing how much. If you had churn on a scale of 0 to 10, do you compensate for a churn of 2 or 5 or 10. So somewhere you still need to measure it and get a quantative amount.

(1) would seem to be half the problem as in developing software to perform the processing,  You would also need different models to apply for the different atmospheric messes that can be created a heat haze will be different to the jetstream. The Met Office has just bought a new supercomputer to do this, they could be willing to sell you the old one.

A magnetic lazy susan would be really useful..

Would they also be really expensive?

They would cost more and ultimately what is the actual advantage over what is presently used?

[NickK]

The problem of (1) would seem to be that you need to first measure the churn of the atmosphere in order to process it and remove it. Knowing there is some, is different to knowing how much. If you had churn on a scale of 0 to 10, do you compensate for a churn of 2 or 5 or 10. So somewhere you still need to measure it and get a quantative amount.

(1) would seem to be half the problem as in developing software to perform the processing,  You would also need different models to apply for the different atmospheric messes that can be created a heat haze will be different to the jetstream. The Met Office has just bought a new supercomputer to do this, they could be willing to sell you the old one.

Hmm I think it's more of an information problem.

If you have a picture (let's call it "I" and it's 2D) the problem is that the picture of the Object, O, is that as you've said there's varying amounts of churn over the picture - including areas where the churn has caused parts of the picture to be overlaid - thus being impossible to retrieve.  A bit like 2+2=4 but you only know 4 however it could have been made up of 1+3 1*4 or 2*2.. and without knowing that you'll not be able to get those parts of the picture (i.e. 1+3) back. Which leaves two options - ignore it by masking it out for that image or process the picture as 3D (2D pictures over time) and hope that part of the picture still provides enough to distinguish. It will all be relative but it's likely to be enough to provide corrective action.

Would they also be really expensive?

They would cost more and ultimately what is the actual advantage over what is presently used?

My thinking here is that a horseshoe mount with a magnetic lazy susan would be very accurate - enough for imaging with a dob or a large mirror/load.

[rowan46]

Sorry Nick I can't help you with your mad idea as I don't speak computer but here is my mad idea a guided alt az imaging sysyem. something like a smart eq  but instead of fitted onto a dovetail the scope fits into a rotating geared ring  then using either an off axis guider or a scope attached  so that it orbits the imaging scope the rotation could be fed in and used for guiding. the only advantage over a standard derotator i can see is manufacture it must surely be easier to build it all into the mount rather than hanging everything off the back off the focusser. But the advantages of an accurate alt az  system are obvious for the mobile british astronomer. It would be lighter more portable and no polar alignment necessary so a quick setup. Who is going to build me one?

[NickK]

Sorry Nick I can't help you with your mad idea as I don't speak computer but here is my mad idea a guided alt az imaging sysyem. something like a smart eq  but instead of fitted onto a dovetail the scope fits into a rotating geared ring  then using either an off axis guider or a scope attached  so that it orbits the imaging scope the rotation could be fed in and used for guiding. the only advantage over a standard derotator i can see is manufacture it must surely be easier to build it all into the mount rather than hanging everything off the back off the focusser. But the advantages of an accurate alt az  system are obvious for the mobile british astronomer. It would be lighter more portable and no polar alignment necessary so a quick setup. Who is going to build me one?

You could use a plastic tube with scope rings to hold the scope. Mount the guider to the plastic tube .. use plate solving to aid the 'plonk down and it automatically models the tracking required'.

Actually- what if you built this into a set of scope rings? you mount the scope normally in the rings, the dovetail then mounts to the outside. That way you can use it for hyper star too.

The amount/direction of rotation would vary with the position relative to polaris or southern PA point.. knowing the plate solve give you the location RA/DEC and therefore the location relative to the PA. Then the rotation is a function of the RA/DEC. No star alignment required beyond the first match... but the more plate solving done - the more accurate it would be.

[rowan46]

You could use a plastic tube with scope rings to hold the scope. Mount the guider to the plastic tube .. use plate solving to aid the 'plonk down and it automatically models the tracking required'.

Actually- what if you built this into a set of scope rings? you mount the scope normally in the rings, the dovetail then mounts to the outside. That way you can use it for hyper star too.

The amount/direction of rotation would vary with the position relative to polaris or southern PA point.. knowing the plate solve give you the location RA/DEC and therefore the location relative to the PA. Then the rotation is a function of the RA/DEC. No star alignment required beyond the first match... but the more plate solving done - the more accurate it would be.

how much is it going to cost me for you to build it ?

[NickK]

how much is it going to cost me for you to build it ?

I'm sure someone with a 3D printer could be coxed into producing a prototype

[rowan46]

GINA

[NickK]

Also making an automatic Alt-Az adjust for NEQ6 mounts (perhaps replacing the base but still tripod capable) with servo worm gears for adjustments to the PA. That would be a plonk down and let the plate PA system then adjust automatically without needing the human to attempt to adjust.

[Gina]

Also making an automatic Alt-Az adjust for NEQ6 mounts (perhaps replacing the base but still tripod capable) with servo worm gears for adjustments to the PA. That would be a plonk down and let the plate PA system then adjust automatically without needing the human to attempt to adjust.

I've been thinking of making a remote controlled PA alignment for my NEQ6 that will be used in my mini observatory - the one that is only big enough for the gear and certainly not big enough for me ti fit into

[Gina]

GINA

Your rang, m' lord?

[Peter Drew]

I love "mad" ideas, specially if they work. My 30" F4.1 mirror 35mm thick at the edge seems to give round star images despite resting on a full aperture layer of industrial standard bubble plastic offering approx 750 points of contact, so what is all this PLOP and triangles and whiffle plates all about?. The mirror also has a 3" perforation holding the mirror in place laterally on an aluminium boss screwed to a substantial backplate.

My "mad" idea which I have not tried in practice is whether a small but quality EQ mount could be slave connected motor to motor with a large DIY mount to provide reasonable tracking.    

[NickK]

I love "mad" ideas, specially if they work. My 30" F4.1 mirror 35mm thick at the edge seems to give round star images despite resting on a full aperture layer of industrial standard bubble plastic offering approx 750 points of contact, so what is all this PLOP and triangles and whiffle plates all about?. The mirror also has a 3" perforation holding the mirror in place laterally on an aluminium boss screwed to a substantial backplate.

My "mad" idea which I have not tried in practice is whether a small but quality EQ mount could be slave connected motor to motor with a large DIY mount to provide reasonable tracking.  

Hmm that means you need very precise polar alignment between the two. You could do this mechanically.. or via electrical. The problem with both is down to keeping the error as small as possible especially as he large mount may have very different tracking characteristics. You could use a belt drive but.. the poor existing motor would then have the mass of the large mount to drive which could put quite a bit of stress on the motor and the power driver circuit.

Now I have the garage work top almost finished and in position.. I'm thinking about ordering some 20AWG copper wire, some magnets and a couple of drivers that I can control to make a prototype direct drive motor. Question is.. should I look at fast switching digital power to control or varying analogue..

[Gina]

If I were to start thinking about a third pier and mount I would resurrect my home made mount project.  It would be a bit easier now with a 3D printer.  My previous design was mainly in wood with aluminium tubes for the axles and large acrylic discs from which to make the worm wheels.