Canadian Brewer Spectrometer Network

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====== Micrometer ======
Everything about micrometers!

===== Micrometer terms explained! =====

{{:docs:micrometer_terms_explained.jpg?1600|}}
==== Software Micrometer Movements ====
It is important to check to see if the micrometers can actually move from one end to the next without getting jammed, or having lack of spring tension. There two ways to check for this.\\
Enter teletype mode via <key>MM</key> while in menu.\\
Method 1: The Easy way\\
  - Type TMAX and enter
  - The micrometer 1 should now move towards the bulkhead, ensure the micrometer doesn't get jammed, the grating arm does not hit the LED
  - Type TMIN and enter
  - The top micrometer 1 should now move towards the mirror, ensure the micrometer doesn't get jammed and ensure there is still go spring tension after the micrometer reaches the end. The push rod should not be resting on the micrometer lip either.
  - Type BMAX and enter
  - The micrometer 2 should now move towards the bulkhead, ensure the micrometer doesn't get jammed, the grating arm does not hit the LED
  - Type BMIN and enter
  - The top micrometer 2 should now move towards the mirror, ensure the micrometer doesn't get jammed and ensure there is still go spring tension after the micrometer reaches the end. The push rod should not be resting on the micrometer lip either.
<hidden Method 2: The methodology and how to do it if you don't have the correct mm.rtn>, you move the micrometer by (Cal Step) + (Zero position).\\
Examples: If (Cal Step)+(Zero Position) = x
<code | dosbox teletype>
>M,10,-x
 - This will move the micrometer towards the mirror
>M,10,x+1
>M,10,-1
 - Type the absolute value for the movements (x-1, ie x=2121 --> 2121 +1 = 2122)
 - This will move the micrometer back to the measuring position, the -1 will reset the zero location 

</code>
To move the micrometer to the bulkhead position, find the highest step number in either the UV or a CJ file, let that number by y.
starting from your zero position, run the following.
<code | dosbox teletype>
>M,10,y
</code>
Refer to [[motor|Motor Positions]] for the motor numbers
</hidden>
===== Adjusting from 302nm to 296.7nm line =====
==== Issue with 302nm's peak ====
The reason that line 302nm was originally picked was because that one of the closes peaks to the micrometer's reference point. However the issue with this is that 302nm has a duplex meaning very close to that peak, there would be a smaller peak which could cause issue if the instrument steps were off and found the wrong peak. Thus the line 296.7nm was picked. This line is a bit further away from the original 302nm, but it does not have any duplex which allows a larger margin of error of the micrometer stepping. 
\\
==== Finding the new values ====
To find the new cal step, we will first open the latest CH scan. {{:misc:ch079.png?200 |}}\\
From here, we'll look for wavelength //3000// and //2965//, then note down the step. (In this case, //2856// and //2358//) The reason 2965 taken is because that is the closes scan to 296.7 and this will be close enough for the instrument to finalize the newest scan (This is the same case for 302nm -->3000. From there we can find the differences between the two to find the new cal step required. In this case we will do //2856// - //2358// = **498**.\\
With those differences, you can find the new cal step by adding **498** to the current cal step. This can now be adjusted in the ICF file.\\
Once we have the cal position, we need to adjust both the zero position and the micrometer offset.\\
<key>Zero Position</key> - <key>Cal Step Differences</key> = <key>New Zero Position</key>\\
<key>Micrometer offset</key> - <key>Cal Step Differences</key> = <key> New Micrometer offset</key>\\
These values should be entered into the ICF.

\\
\\
\\
==== The Explanation ====
{{ :misc:micrometer_adjustment.png?600 |}}
The hardest part of micrometers is to understand how all the steps are calculated and where the steps are coming from.\\
All the calculations for the ICF is from the left to right.\\
The movement via MM, positive is on the right, negative goes to the left.\\
Note: The typical cal step is around 900+ steps.
\\
\\
===== Finding Micrometer #1 Offset From Scratch =====
==== Finding the hp line (Double Spectrometer only MKIII) ====
Go into teletype mode by going into [[mm|MM]]\\
<code | dosbox teletype>>B,2
>M,1,0
>M,10,-1
>M,9,1001
>M,9,-50:R,2,2,5:O:A
</code>
The last line will move the bottom 50 steps backwards (while setting the new reference) and read the counts on slit 2 for a cycle of 5 times and output to the screen. As it does this you should be able to see the counts increase and get a peak. Once that is found, press <key>HOME</key>. That will end the loop. Count the number of lines output back to the peak and multiple that by 50. This is the number of steps you need to add to the offset later. type <key>exit</key> to exit back to the menu.
Now run <key>fr</key> to find where the micrometer was found. Take that and add the number of steps found in the previous step, this is your new micrometer 2 offset

==== Finding the HG line ====
=== Using CI ===
Run the CI routine.
<code | dosbox menu>PDB1W1CI
</code>
Select 1 step increments for CI for a fine resolution.

=== Plotting the results ===
Once brewer has completed the CI scan, the results can be plotted on excel. \\
{{:misc:ci-good.png?600|This graph shows a good CI scan where the HG peak is as expected on 2967.28.}}\\
This graph shows a good CI scan where the HG peak is as expected on 2967.28.

While its always nice to see the peak where it is expected, sometimes it doesn't come back as expected like this graph.
{{:misc:ci-bad.png?600|HG peak not lining up with the 2967.28 reference line}}\\
To solve that we will first find where the peak that was suppose to be at 2697.28 is. In this case, it is at <key>2929</key>. We then take that and find how far away it is from the reference line, <key>2967</key> - <key>2929</key> = <key>38</key>. After that to find the difference in the offset, we take that number and divide it by <key>0.065</key>¹.\\
<key>38</key>/<key>0.065</key>=<key>584.62</key>\\
Now take that and add² it to the micrometer 1 & 2³ offset\\

=== Manually via mm ===
This method should only be used if you are somewhat close to the HG line to begin with otherwise you may get confused with the other HG 

=== Notes ===
¹The Brewer MKIII Operators Manual, Appendix H, motor positions for instrument control table, describes micrometer movement as” 576 steps/mm - wavelength change of 0.0065 nm/step (positive steps increase wavelength and decrease micrometer setting) . The above example is in angstroms: 0.0065 nm/step equals 0.065 angstroms / step\\
² In this case, the peak is before 2967 so we add, if it is beyond 2967, we would subtract to the micrometer offset\\
³ Micrometer 2 offset needs to be changed for MKIII instruments.\\



===== MKIII Grating scans=====
{{ :docs:grating_scans.pdf | Troubleshooting Grating Scans}}

===== Other docs =====
{{ :docs:micrometer_optical_led_reference_triggering.pdf |Micrometer Optical LED Reference Trigger}}\\
{{ :docs:finding_micrometer.pdf |Finding the Micrometer}}\\
{{ :docs:micrometer_optical_led_reference_triggering.pdf |}} - Includes the Schmitt Trigger schematics.