Expanding on the single-layer model, I added the second, third, and fourth layers to the stack in COMSOL. Eigenfrequency analysis run times increased exponentially as the model multiplied in complexity. The following images document the some of the important eigenfrequencies:

First Eigenmode: y-translational, 3.34 Hz:

Second Eigenmode: x-translational, 3.39 Hz:

Third Eigenmode: z-rotational, 3.88 Hz:

Sixth Eigenmode: z-translational, 8.55 Hz:

As expected, the eigenfrequencies are generally lower, but still in the same range, as the single-layer model, because of greater mass but constant weight-per-spring distribution.

Next Steps:

1) Extend a single stack to the full stack system, which consists of three stacks like this. Perform similar eigenmode analysis.

2) Analyze the mirror suspension system and incorporate a similar pendulum on the top plate.

3) Make transfer function measurements between seismic and mirror motions.

Some clarification is warranted regarding the different shapes of stacks. Corrections are appreciated:

1) The single-leg stack that I just completed should function as a working model for the IO, OO, and MC1/3. Rana commented, however, that the current dimensions are slightly off for MC1/3 (which makes sense since I could only find drawings for the IOC). If anyone knows the whereabouts of similar drawings for MC1/3, I'd much appreciate it.

2) A triple-leg stack can model the BS, ITMX, and ITMY chambers. I don't have exact dimensions for these, but I can make decent approximations from to-scale stack drawings. I'll probably work on a model for this style next, since at least I have some information regarding this version.

3) The MC2 chamber has its own stack model, about which I haven't found any drawings in the binders. I can't start on MC2C at all until I find such drawings.

Now that venting is complete, this is a request for anyone who opens any chamber:

1) Please notify me immediately so I can take pictures of the stacks in that chamber.

2) If I'm not around, please take a few pictures for me. I'm most interested in the shape, number of layers, size, and damper arrangements of each stack.

This is most important for the MC1/MC3 chamber, MC2 chamber, and BS/ITMX/ITMY chambers.

Thanks!

Over the past couple days, I discovered a simple, direct method for calculating frequency responses with a combination of COMSOL and any plotter such as Excel or MatLab. The simple case of rectangular prism of steel was analyzed using this method; details will be posted shortly on the COMSOL Wiki page. The frequency response matched theoretical reasoning: the bar acts as a simple mechanical low-pass filter, rapidly attenuating driving frequencies at the base beyond the first eigenmode.

It therefore shouldn't be too difficult to extend this analysis to the MC1/MC3 stack. The many eigenfrequencies will produce a more complicated transfer function, and so more data points will be taken.

The major shortcoming of this method involves dealing with the imaginary components of the eigenfrequencies. As of now, I haven't found a way of measuring the phase lag between the drive and the response. I also haven't found a way of changing the damping constants and therefore playing with phase components.

I have successfully completed a preliminary transfer function measurement test on the MC1/MC3 stack in COMSOL. Using the measurement scheme described on the Wiki, I initialized a 1 N/m^2 sinusoidal perturbation on the bottom of the stack and measured the maximum displacement of the top layer. This preliminary test just calculated the responses to 1-,2-,3-,4-, and 5-Hz drives along the x-axis (pictures attached).

Currently, I am rerunning the same test but from 1-10 Hz with 0.1-Hz steps. When both x- and y-axis responses have been plotted, I can move on to repeating this entire process on the MC2 stack.

I completed the frequency domain analysis mentioned previously in the x-direction. Although I ran it from 1-10 Hz, with 0.1-Hz increments, COMSOL was unable to complete the task past 7 Hz because the relative error was beyond the relative tolerance. To solve this issue, I'd have to rerun the simulation with a finer mesh, an unfavorable option because of the already-extensive run times. The Bode magnitude plot from this simulation is attached:

This simulation raises some questions about the feasibility of this method:

1) Do we have the computing power necessary?

I already moved my work from my personal Mac Pro to Kallo (4 GB --> 12 GB RAM difference). Now, instead of crashing the program constantly, I typically wait a half hour for a standard run of the model. Preferably, I could move my work to Megatron or some other workhorse-computer... but I also know that many of the big boys are already being strained as is.

2) Is it possible to take measurements through Matlab?

This way, I could write a script to instruct COMSOL and just run a few tests at a time overnight. Also, I wouldn't have to sit and record measurements manually as I've done here. The benefits of such an improvement warrant further attention. I'll work on this option next.

3) Up until what frequency do we need to model?

As I've shown, normal meshing yields data up to 7 Hz. Is this enough? Do we need more data? Certainly not less, I'm quite sure. We need to keep in mind that as frequency range increases, run times increase exponentially.

4) How do we incorporate gravity into the equation?

Gravity will produce a bit of extra force in the non-restoring direction for off-axis deviations, slightly decreasing the expected frequency. Whether or not this is an important effect is questionable, since the deviations are typically on the order of a micron, which is orders of magnitude smaller than the initial displacement I'm using on the base. I've decided to ignore this complication for now.

I have discovered a method of completely characterizing the 6x6 response of all six types (x-,y-, and z- translational/rotational) of oscillatory disturbances at the base of the stack.

• "Tipping" drives are trivial, and simply require a face load in the appropriate direction.
• "Tilting" drives could use a torque, but I am instead implementing multiple edge loads in opposing directions to create the appropriate net curl. This curl will be kept constant across the three axes for sake of comparing the resulting transfer functions.
• "Tipping" responses are once again trivial, and merely require the displacement vector of the top center coordinate to be recorded.
• "Tilting" responses require the normal vector to be recorded and manipulated to produce the angular coordinates (assuming right-handed coordinate system):
  • θ_x = tan^-1(x/z)
  • θ_y = tan^-1(y/z)
  • θ_z = tan^-1(y/x)
    

The first three concepts have been confirmed through simulations to produce correct transfer functions. The last test seems to be producing some problems, in that the vector normal to the equilibrium position (an obvious and useless piece of information) is sometimes given instead of the vector normal to the position of maximum displacement. This means that, as of now, I have the capability of measure the half of the complete 6x6 matrix of transfer functions in the coming weeks. The first three of eighteen transfer functions are attached below and will be included in my progress report.

Over the past 36 hours, I've run full-fledged FDAs on KALLO.

The transfer functions for translational drives and responses are neatly described by the attached transfer function "matrix."

Next steps:

1) Extend the 3x3 analysis to include tilts and rotations in a 6x6 analysis.

2) Figure out how to do the same types of tests for phase instead of displacement.

I reran the FDA in COMSOL on the MC1/MC3 Stack and produced the following Displacement-Displacement Transfer Functions:

X-Translational Drive has a blue background

Y-Translational Drive has a red background

Z-Translational Drive has a green background

Obtaining the Displacement-to-Phase part of the Transfer Function still produces difficulties -- I'm still working on the COMSOL-Matlab interface to perhaps better facilitate this.

RA: I have deleted those plots because they weren't transfer functions. Transfer functions must always be the ratio of something to something. For example: if I had a nickel for every bad plot I see, I would be a millionaire. In that example, the transfer function would have the units of nickels/plots. For the stacks, it should be meters/meter.

My apologies for the mislabeled axes on my previous plots. They have been corrected to a ratio (in./in.), as Rana so kindly suggested in his helpful, not-at-all-condescending response.

I have chosen to stay in the English system because all of the original stack drawings are in inches as well.

Time Domain Analysis on a Driven, Damped Simple Pendulum has produced a method for implementing gravity.

COMSOL made this simple task a cryptic one: the following methods had previously failed:

• Previous Frequency Domain testing lead to unwanted oscillations of all loads.
• Prescribed accelerations at first seemed to create a constant gravity, but instead incorrectly constrained net acceleration to the inputted amount

Methodology:

1) An (approximately) impulse displacement was applied in the horizontal direction. The pendulum bob's displacement was observed for varying pendulum lengths.

2) The drive and response displacements vs. time were FFT'd to produce transfer functions.

3) The fundamental frequencies were inverted, squared, and plotted against frequency.

4) Since the graph is linear with an R^2 of over 0.99, it is reasonable to assume that gravity is properly acting as a restoration force.

I re-centered the ITMX & ITMY Optical lever beams today since they were off. First I aligned the beam into the vacuum so that it went through the center of the on table optics and then tweaked the receiver optics alignment.

There are several bad practices on these which probably makes them drift:

• plastic bases on some lens mounts
• some lens mounts are fastened with a single dog instead of two
• there is no need to use dogs on mounts that have screw holes. Just put the mount so that 2 screws with washers can be used. The placement for these is not so critical.
• Use less steering mirrors! The ITMY OL path has 5 optics the beam enters the vacuum!!!

According to the datasheets, the laser has a beam diameter of 0.6 mm and a divergence angle of 1.3/2 mrad. So we can just calculate the right lens positions next time and not have to experiment with the whole visible laser lens kit.

For next Wednesday's cleanup, someone should volunteer to make the mounts more stable for the ITMs.

 Steve had me measure the RIN of a JDSU HeNe laser. I used a PDA520, and measured the RIN after the laser had been running for about an hour, which let the laser "settle" (I saw the low frequency RIN fall after this period).

Here's the plot and zipped data.

Steve: brand new laser with JDSU 1201 PS

 At Rana's request, I've made an in-situ measurement of the RIN of all of our OpLevs. PSL shutter closed, 10mHz BW. The OpLevs are not neccesarily centered, but the counts on darkest quadrant on each QPD is not more than a factor of a few lower than the brightest quadrant; i.e. I'm confident that the beam is not falling off. 

I have not attached that raw data, as it is ~90MB. Instead, the DTT template can be found in /users/Templates/OL/ALL-SUM_141125.xml

Here are the mean and std of the channels as reported by z avg 30 -s, (in parenthesis, I've added the std/mean to estimate the RMS RIN)

Dividing each spectrum from DTT by these mean values gives me this plot:

ETMY is the worst offender here...

[Rana, Diego]

We manually realigned the BS and PRM optical levers on the optical table.

The IFO_overview of oplevs seems ok, The servos are working fine. The green arms are locked, but master and oplev_summary monitoring screens are not.

I'm proposing to Erick G. to postpone the oplev noise measurement.

Manasa and Steve,

Is this what you want?  Dashed lines are dark.

BS and PRM oplevs are blocked for this measurement. I will restore to normal operation at 4pm today.
 

It doesn't work with the lens in there, but it seems pretty close. Please leave it as is and I'll play with it after 5 today.

To test what the inherent angular noise of the HeNe 1103P laser is, we're testing it on a table pointing into the BS OL QPD with only a few steering mirrors.

From the setup that I found today, I've removed the lens nearest to the laser (which was used for the BS and PRM) as well as the ND filter (what was this for?) and the lens placed just before the BS QPD.

With the ND filter removed, the quadrant signals are now ~15000 if we misalign it and ~9000 each with the beam centered.

In order to calibrate the OLPIT_IN1 and OLYAW_IN1 signals into mm of beam motion, I misaligned the mirror just before the QPD. The knobs on there actuate the 100 TPI screws and the knurling on the knob itself has 10 ridges, so that's 36 deg per bump.

PIT cal ~ 1.55 (knob deg / count) -->> 10 microns / count --->>> 10 urad / count

YAW cal ~ 1 (knob deg / count)  -->> 6.5 microns / count --->>> 6.5 urad / count

Distance from the 45 deg turning mirror to the QPD silicon surface is 23 cm. Distance between knob tip and fixed pivot point is ~4 cm. 1 knob turn = 0.01" = 0.254 mm = 0.254/40 radians of mirror angle.

So 360 deg of knob gives 2*0.254/40 = 0.012 radians of beam angle = 0.012 * 230 mm ~2.3 mm of beam spot motion. Or 6.4 microns of translation / deg of knob.

The distance from the face of the laser to the QPD is 96 cm.

The punchline is that the laser shows a level of noise which has a similar shape to what's seen at LLO, but 10x lower.

The noise at 0.05 - 0.2 Hz is ~2-3x worse than the PR3 at LLO. Not sure if this is inherent to the HeNe or the wind in our setup.

BS & PRM oplev is restored. Note: the F -150 lens was removed right after the first turning mirror from the laser. This helped Rana to get small spot on the qpd.

It also means that the oplev paths are somewhat different now.

I'm getting ready change the Newport Ultima U100-AC to SS-Polaris-K1  LOW DRIFT MIRROR MOUNTS

Note: there is only one lens in the PRM lunching path (  only realized later ) , so the spots are large ~ 3 mm at PRM qpd and ~4.5 mm at BS qpd

The spots are well centered.

Atm3,  the spots were well centered yesterday ( the PRM is misaligned in pitch and retsore does not work today )

[yutaro, ericq]

We made the beam spot on QPD for the oplev of ETMY centered by changing the orientation of the mirror just before the QPD.

Before doing this, we ran dithering for Y arm and froze the output of ASS for Y arm.
 

[yutaro, Koji]

We made the beam spot on QPD for the oplev of ITMY centered by changing the orientation of the mirror just before the QPD.

Before doing this, we ran dithering for Y arm and froze the output of ASS for Y arm.

Based on elog 1403, I calibrated the oplevs for ITMY/ETMY.

Summary of this method is following:

We lock an arm, and slightly misalign one mirror of the arm. Then, the transmission of the arm starts to decrease quadratically as the misalign angle of the mirror changes. Here, how much the transmission decreases in terms of the misalign angle is determined by geometry of optics, so we can see how much the angle really changes from this quadratic curve.

RESULTS  

These are the relationship between misalign angles measured by oplev (the units are based on the calibration for now) and transmission power.

(I updated following figures on Nov 19 2015. You can find the figures I attached once here in the zipped folder attached.) 

According to this measurement, ratio of the calibration factor derived with this measurement (NEW) and the calibration factor for now (OLD), i.e. NEW/OLD was:  

ETMY_PIT: 5.0265  --->> 5.3922 (without an outlier; the outlier I removed is shown in the figure in zipped folder attached.)

ETMY_YAW: 4.6205

ITMY_PIT: 1.5010

ITMY_YAW: 1.2970

This results show that calibration of oplevs for ITMY is kind of OK, but that for ETMY is so BAD and the calibration factors should be updated.

NOTE

The calibration factors of the oplevs for ETMY/ITMY are   NOT UPDATED YET.  I updated on Dec 11, 2015

If these results are reliable, I will update them tomorrow.   

OMG. Please try to use larger fonts and PDF so that we can read the plots.

I'm not sure that these calibration measurements are reliable. I would feel better if Steve can confirm them using our low accuracy method of moving the QPD by 1 mm and doing trigonometry.

I'm sorry. I will be careful about that. And I updated the plots in elog 11785.

 In this morning, Steve and I looked at the ETMY table and we found that the measurement you suggested might interfere with other optics or detectors because of space constraint. So, before doing this measurement, I roughly estimated the calibration factors for ETMY oplev by using the rough value of the arm length of the optical lever and the beam width of the light just before the QPD.

How I got the arm length and the beam width:

I measured the length of the optical path between ETMY and the QPD. Then I measured the beam width with an iris to screen the beam. To get the beam width from the decrease of the power of the beam detected by QPD, I used this formula: .

Then I got:   (arm length) = 1.8 +/-0.2 m,    w= 0.56 +/- 0.5 mm.

How I estimated the calibration factors from these:

The calibration factors (such as C1:SUS-ETMY_OL_PIT_CALIB; (real angle) / (normalized output of QPDXorY)) can be calculated with: . Then, I got

,

though the calibration factors, C1:SUS-ETMY_OL_PIT_CALIB C1:SUS-ETMY_OL_YAW_CALIB, right now are 26.0 and 31.0, respectively. (If I express this in the same way as elog 11785, 5.0 and 4.2 for ETMY_PIT and ETMY_YAW, respectively. they are consistent with yesterday's results.) 

I believe that the calibration factors I estimated today are not different from the true values by a factor of 2 or something, so this estimation indicates that the oplev calibration measurements I did yesterday are reliable, at least for the oplev for ETMY. 

I made the beam spot on QPD for the oplev of ITMY centered by changing the orientation of the mirror just before the QPD.

Before doing this, I ran dithering for Y arm and froze the output of ASS for Y arm.

With the same method as reported in elog 11785, I calibrated oplevs for ITMX/ETMX.

RESULTS 

According to this measurement, ratio of the calibration factor derived with this measurement (NEW) and the calibration factor for now (OLD), i.e. NEW/OLD was:   

ETMX_PIT: 4.470

ETMX_YAW: 2.5970

ITMX_PIT: (-)1.1102

ITMX_YAW: 1.8173

NOTE

The calibration factors of the oplevs for ETMY/ITMY are   NOT UPDATED YET. I updated on Dec 11, 2015

http://blogs.mathworks.com/loren/2007/12/11/making-pretty-graphs/

Let Loren help you make your Oplev data readable to humans.

I updated the figures. I think it's easier to read now.

Based on calibration measurement I have done (elog 11785, 11831), I updated calibration factors of oplevs on medm screen as follows. Not to change loop gain oplev servo, I also changed oplev servo gain.

C1:SUS-ETMX_OL_PIT_CALIB, C1:SUS-ETMX_OL_PIT_GAIN

(45.1,16) => (200,3.5)

C1:SUS-ETMX_OL_YAW_CALIB, C1:SUS-ETMX_OL_YAW_GAIN

(85.6,8) => (222,3.0) 

C1:SUS-ETMY_OL_PIT_CALIB, C1:SUS-ETMY_OL_PIT_GAIN

(26,-16) => (140,-3.0) 

C1:SUS-ETMY_OL_YAW_CALIB, C1:SUS-ETMY_OL_YAW_GAIN

(31,-21) => (143,-4.5) 

C1:SUS-ITMX_OL_PIT_CALIB, C1:SUS-ITMX_OL_PIT_GAIN

(110,8) => (122,7.2) 

C1:SUS-ITMX_OL_YAW_CALIB, C1:SUS-ITMX_OL_YAW_GAIN

(81,-11) => (147,-6) 

C1:SUS-ITMY_OL_PIT_CALIB, C1:SUS-ITMY_OL_PIT_GAIN

(159,15) => (239,10) 

C1:SUS-ITMY_OL_YAW_CALIB, C1:SUS-ITMY_OL_YAW_GAIN

(174,-21) => (226,-16) 

After making sure that the upper UGFs were properly in place, I saved these settings to the SDF files. Thanks Yutaro!

On the control room monitors, I noticed that the IR TEM00 spot was moving around rather a lot in the Y arm. The last time this happened had something to do with the ETMY Oplev, so I took a look at the 30 day trend of the QPD sum, and saw that it was decaying steeply (Steve will update with a long term trend plot shortly). I noticed the RIN also seemed rather high, judging by how much the EPICS channel reading for the QPD sum was jumping around. Attached are the RIN spectra, taken with the OL spot well centered on the QPD and the arms locked to IR. Steve will swap the laser out if it is indeed the cluprit.

ETMY He/Ne 1103P  body temp is  ~45 C The laser was seated loosely  in the V-mount with black rubber padding.

The enclosure has a stinky plastic smell from this black plastic. This laser was installed on Oct 5, 2016 See 1 year plot.

Oplev servo turned off. Thermocouple attached to the He/Ne

It will be replaced tomorrow morning.

Steve, Craig, Gautam

Today Steve replaced the ETMY He/Ne sr P919645 OpLev laser with sr P947049 and Craig realigned it using a new AR coated lenses.

Attached are the RIN of the OpLev QPD Sum channels.  The ETMY OpLev RIN is much lower than when Gautam took the same measurement yesterday.

Also attached are the pitch and yaw OLG TFs to ensure we still have acceptable phase margins at the UGF.

The last three plots show the optical layout of the ETMY OpLev, a QPD reflection blocker we added to the table, and green light to ETMY not being blocked by any changes to the OpLev.

Gautam and Steve,

New JDSU 1103P HeNe oplev laser RIN was measured on the SP table with cover on.

This is the beginning of an effort to improve oplev laser noise.

The laser got much better at low frequency as it warmed up. This laser is almost as good as the electronics?

Dark noise cal was the same today as it was 2 days ago.

This measurement looks bogus - the difference between dark and not dark is not significant enough to believe. Need to figure out how to match better into the ADC range.

Corrected oplev laser RIN plot at day 3

RXA:

1. to measure RIN, the lever arm should be really short, not long.
2. the beam should be 3x smaller than the active area of the diode
3. the specular beam should be dumped on a razor dump.
4. we need to make a summary page for HeNe laser testing so that we can see 24 hour specgrams of these things for ~3-4 lasers at the same time.
5. We should add specgram stuff for the existing HeNe SUM channels on the active OLs.

GV: The channel the PD Steve is using is hooked up to C1:ALS-FC_X_F_IN. As I found out today, there can be considerable RF pickup between the C1:ALS-FC_X_F_IN and C1:ALS-FC_Y_F_IN channels, which share a common 4-pin LEMO cable - this is because the rise time of the square wave output of the Wenzel dividers is <1us, so suitability of this particular channel for the RIN measurement set up has to be reconsidered. Perhaps we can use one of the six spare PEM channels over at 1X6. 

Gautam and Steve,

We did the following:

1, switched data channel  from  C1:ALS-FC_X_F_IN to C1:PEM-MIC_1_OUT_DQ   Actual connection at 1X7 rack, input C17

    Tested channel with 1Hz, 100 mV sine wave through DV

2, placed BS into the beam path so the reflected value on the PDA100A 0.1mW,  beam od ~1mm, beam path lenght 11 cm, gain 20dB 3.7Vdc

    The full output of this 1103P 2.8 mW was saturating the PDA100A

Summery :finding it to be too good to be this good

ETMX oplev laser is dead. It will be replaced this after noon. Sus damping recovered.

This 3 years old HeNe [ JDS 1103P, sn 351889 ]  has been dying for some time or just playing possum at age 1,126 days

I did not replace the ETMX oplev laser because I was unable to bring up the the C1ASC_ETMX_OPTLEV_SERVO  medm screen on laptops.

JDSU 1103P. sn T8070866, made March 2007, output power 2.7 mW,  on pd 17,750 counts,

GV 17 March 3pm: I found the Innolight NPRO was off when I walked down to the X end earlier, possibly was accidentally tripped during the Oplev laser replacement. I turned it back on.

We are planning to test 3 identical 1103Ps RIN with  continous temp monitoring and control later.

Selected  temp sensor   Platinum RTD 1PT100KN1515CLA   or           RTD-830 

Temp controller  with analoge output 0-10Vdc, CNi854  and external dc pulse driven  relay

Order placed 4-12-17 for sensor  RTD-830,  controller CNi8-5-4 and relay  SSRL240DC25 = ~$500.

Still need: fuse, fuse housing, on/off switch, female  AC receptical, chassy box and AC power cord.

I'm suspicious of this temperature sensor comparison. Usually, what they mean by accuracy is not the same as what we mean. I would not buy these yet. How about we just use what Caryn used several years ago (elog search) ?

  PS  Steve LM34             

Andrew and I set up the razor blade beam profiling experiment for He-Ne lasers on the "SP" table.  Once I receive the laser safety training, I will make power measurements and fit it to an erfc curve from which I will calculate the gaussian profile of the beam. I'm attaching some pictures of the setup. 

Least count of the micrometer - 2 microns 

Laser  : Lumentum 22037130:1103P

Photodetector : Thor Labs PDA100A

I had measured the y-profile of the beam of Friday at 5 axial locations and fit them to an erfc function using the lsqcurvefit function of MATLAB. 

The results were as follows - 

z(cm)    w (in)

4          0.0131

10        0.0132

15        0.0137

20       0.0139

25        0.0147

I left w in inches in the intensity plots as MATLAB gave more accurate fits for those values.

I converted these to S.I while making the spot-size vs z plot and the corresponding values in microns were 

332.74, 335.28, 347.98, 353.06, 373.38.

On fitting these values to the formula for the spot size of a Gaussian beam, the beam waist came out to be 330.54 microns and the location of the beam waist was at z=-2cm, where z=0 marks the head of the laser. 

TO-DO : Measure the spot size of the beam at more axial points to obtain a better fit. 

              Measure the x-profile of the beam. 

              Analyse the error in the spot sizes and corresponding error in the beam waist. 

I have attempted to calculate the instrument error (micrometer least count) using the values of the spot size obtained by the least squares fitting method. This error is large towards the centre of the beam as the power varies significantly between adjecent markings of the micrometer. Using the new values of error obtained, I used the chi-square fitting minimisation method to further optimise the waist size. 

The modified values are - 

z(cm)    w (in)

4         0.0134

10        0.0135

15        0.0140

20        0.0142

25        0.0150

And the revised values for the beam waist and location are 338.63 microns and -2.65 cm respectively. 

I will now try to use the chi-square stastitic to estimate the error in spot size. 

1. Include several sources of error. Micrometer error is one, but you should be able to think of at least 3 more.
2. There should be an error bar for the x and y axis.
3. Also, use pdftk to put the PDFs all into a single file. Remove so much whitespace.
4. Google 'beautiful plots python' and try to make your plots for the elog be more like publication quality for PRL or Nature.

You may compare your results with this.

RXA: please no, that's not the right way