Leginon

h1. Setup and Calibration for jeol.cfg

All setup and calibrations are done on the computer that has access to JEOL's External COM through temext.dll.

h2. Copy from pyscope/jeol.cfg.template to pyscope/jeol.cfg

The current template is based on a JEM-3200FSC

h2. Modify [tem option] section in pyscope/jeol.cfg according to your scope

h3. Using PLA for image shift

Image shift is normally achieved with IS1.  However, PLA is a sometimes a better choice as it does not induces beam tilt at

the specimen, although its range is more limited.  When an omega filter is part of the scope, this also makes sure the beam not

affected at the entrance of the filter.

h3. CL3 RELAXATION MAG

The center of the beam on some scopes, such as JEM3200FSC at NYSBC, moves whenever CL3 is adjusted.  In such as case, a more stable position can be reproduced if the beam intensity is cycled back and forth through cross-over through a programable procedure called "CL3 Relaxation", found in TEMCON/Option/Lens Relaxation if available.  Leginon emulate that.

If you have this particular problem, set this option to a magnification where the procedure will be performed whenever the magnification is changed to a value larger than the "cl3 relaxation mag" value.  Typically this is set at a value below the magnification for fa,fc, and final exposure so that these become more stable.

For example:

<pre>

CL3_RELAXATION_MAG = 5000

</pre>

h3. Lens Series within MAG1 and LOW MAG modes

There are distinct sets of objective and projection lens settings within MAG1 mode that gives

different scale and neutral values.  We assign each of these lens series (LS) numbers, starting at 1 at

the lowest mags. Similarly, we also named the lowest LOWMAG mode lens series LM1 and assign a

different deflector scale to them.

The order of magnifications is therefore roughly

<pre>

LM1->the rest of LOWMAG->LS1->LS2->LS3->the rest of MAG1

</pre>

* To simply the mapping of magnification to the projection modes, MAG1 will be used if a magnification

can be achieved by either LOWMAG and MAG1*

These four configurations like these therefore define the boundary of each lens series within the mode.

<pre>

LS1_MAG_MAX = 4000

LS2_MAG_MAX = 25000

LS3_MAG_MAX = 100000

LM1_MAG_MAX = 200

</pre>

h2. Run pyscope/scalecalibrator.py to get values for different items in jeol.cfg

With the main viewing screen down do these at the computer with temext.dll registered.

# Open pyscope/jeol.cfg with a text editor and leave it open so that you can enter values as you go.

# Double click pyscope/scalecalibrator.py to start it.

# The script will first make the scope go through all magnifications in LOWMAG and MAG1 range to determine valid magnifications.

# Enter the magnifications at which to calibrate.  Make sure that you include at least one magnification in each lens series that you will use.

# Follow the instruction to shift each coil or mechanism by the amount indicated.

For example, for image shift with IS1,  It says

<pre>

Preparie to calibrate IS1:

Waiting for you to setup the initial condition

</pre>

The initial condition means a visible feature at an easily remembered position such as the central dot on the main screen so that a shift can be recognized.

The distance between the major ticks of the linear scale bar on the main viewing screen corresponds to 1 cm at the film camera (i.e., nominal magnification)

After "hit a key to continue", this original IS1 value is recorded.  You are then asked to

<pre>

Move IS1 by 1.0 cm on Main Screen in x direction

</pre>

This means using x-axis IS1 knob to move the image feature by the amount.  The major ticks of the scale bar on the main viewing screen corresponds to 1 cm at the film camera height.

The new IS1 value is saved when you hit a key to continue.

The output include

<pre>

[def]

IMAGESHIFT_SCALE%LS2%X=8e-8

</pre>

You should then modify this item in jeol.cfg according to the result.

*I do not know which values will change with lens series, nor can we assume that x and y coils have the same scale.  Please let me know what you get.*

*Missing calibration of unused lens series should not cause problem.  There is no need to go through all of them just for the sake of completeness.*

*The scale does not need high accuracy, a 20% error probably is not going to cause failure since there will be a fine calibration done within Leginon.*

*The math for calculating beamtilt coil scale may not be correct.  Please report problem in later Leginon calibrations*

h2. Record standard focus and neutral deflector values

Standard focus and neutral deflector values are the references for relative movements performed in Leginon.  These values are stored in JEM scopes and will only change when engineer alignment is performed.

# Open pyscope/jeol.cfg with a text editor and leave it open so that you can enter values as you go.

# Double click pyscope/standard.py to start it.

# The script will first make the scope go through all magnifications in LOWMAG and MAG1 range to determine valid magnifications.

# Follow the instruction to go through each magnification that you will access.

# At the end the program will summarize the values which you can copy into jeol.cfg

*You may notice as I have that at LS2 (and probably above) the standard defocus is unchanged at different mags.  In this case, put only the standard focus value for the lowest magnification so that the defocii can be modified together in this lens series*

h2. Set up stage backlash options

Backlash correction on JEOL scopes may be different individually.  These options allows tuning of them.

There are two kinds of backlash correction.  Full correction send the stage to a temporary position at a fix distance and direction relative to the final position first, before moving to the final.  The temporary position used in "reduced correction" is at half the distance of the final movement. Its purpose is to save time.

BACKLASH_SCALE:  This has separated X, Y values.  They defines the size of backlash correction (in meters) the stage makes when full correction is performed.  To determine the proper value, observe the movement of the stage when you use TEMCON program "Operation/Specimen Position" to recall a position from memory.