spectrometer angle measurement

Hello all,

I am using arduino due. My idea is to keep two 16 X 2 LCD display to the two opposite ends of a 360 deg circular disc. One is kept at 0 and the other at 180 deg. The problem is this.

Each degree is divided into 60 minutes. When the disc is turned, the angle shown on one LCD1 should increase and the angle on the other should decrease to the same amount as LCD1. The increase or decrease should be in minutes and degrees.

Any help on how to start about. I am thinking of using an gray code encoder for the input.

You have to start with a specification.
What angle increment do you want?

It is going to be quite expensive the more precision you require.
What is turning the disc?
Is it by hand?

What sort of budget do you have? Something that can measure down to minuets of arc is going to be very expensive. It would require a 21600 pulses per rotation sensor. You will not get an absolute sensor that does that.

The LCD display bit is almost trivial compared to your sensor requirements.

A turntable capable of 1/60 degree resolution is probably being turned via a worm drive. Put a rotary encoder on the worm gear and calibrate for backlash during changes of direction.

prrrichy:
Hello all,

I am using arduino due. My idea is to keep two 16 X 2 LCD display to the two opposite ends of a 360 deg circular disc. One is kept at 0 and the other at 180 deg. The problem is this.

Each degree is divided into 60 minutes. When the disc is turned, the angle shown on one LCD1 should increase and the angle on the other should decrease to the same amount as LCD1. The increase or decrease should be in minutes and degrees.

Any help on how to start about. I am thinking of using an gray code encoder for the input.

can you give some examples ?

Thanks all who have interest in this type.

This is like a manual spectrometer what we have in a physics laboratory. This mechanical one is used to measure the refractive index of the material of prism.

The calibrated disc will be rotated in hand. The left side a meter reading will be like 78 degrees 35minutes. The other opposite side 78 30' + 180degrees ie 258 30' will be shown. In the middle I am thinking of attaching either a potentiometer or a encoder.

Thanks for the clarifications sort. I hope this gives the idea

My angle class might be helpful

In the middle I am thinking of attaching either a potentiometer or a encoder.

I think you have an unrealistic expectation of the sort of precision you can get from a pot or an encoder. Even if it were possible to get the precision you claim to want, turning a table by hand is never going to be repeatable enough to be remotely useful.

I think you need to go back to the basics of this project and realistically specify what you want to achieve.

I hope some of the friends understood the problem. To make it clear

SpecFig17.jpg

I think the picture I have shown gives a clear idea of what I am upto. When The telescope (movable) is turned cw or ccw, the readings on the left scale, for example, shows 45deg and 55 minutes, then the right scale will show 180deg +/- 45deg 55'. This is what I am trying to do. I hope it is easier if it were only 360 deg. But it should also show the smaller divisions. because 1deg = 60'

Thanks friends for the idea given
Hope to get new idea

prrrichy:
Hope to get new idea

Point a camera at the vernier scale then write an image recognition program.

prrrichy:
I hope some of the friends understood the problem.

Yes that is exactly what I thought you are doing. Do you not understand my comments?