Exp397T Imaging Lab

Owned by Chieh Peng (Unlicensed)
Last updated: Oct 09, 2022
5 min read

By Chieh Peng, Kara Vadman, Luan Heywood, and Etienne Claassen

 

Summary

EXP397T is a month-long transit with 1 week of coring, returning to Walvis Ridge Hotspot (EXP391) with 9 scientists. No dedicated Imaging Specialist sailed on this transit. All duties were divided among several staff. Chieh and Etienne took care of the general photography duty, including weekly F&F photos and group photos, and closeup. Luan and Kara took care of SHIL, microscopes, and SEM duties.

SHIL

During 397T, the SHIL was used for section halves and 360 imaging at sites U1584A and U1585A. For imaging hardrock 360-degree sections, IMS was pulling the LIMS lengths from the catwalk length rather than the curated length. The SHIL will only measure as far as the reported LIMS length on the screen, and the length cannot be changed directly on the screen. Therefore, we requested every hardrock section length to be changed by developers before 360 imaging. Other than the LIMS length issue, the SHIL operated correctly and without issues.

360-degree image processing was supported onshore by Sandra Herrmann. Quadrant images were transferred zipped files from ship to shore through TAMU Filex. Sandra stitched the whole-round images together, and transferred back to the ship through Filex, and Kara Vadman uploaded to LIMS using 360 Imaging Composite Processor.

Microscopes

Upon scientist request, a microscope objective was swapped out for one of lower power (2.5x).

SEM

The Hitachi SEM (disassembled during 397P) was moved to the Zoom Room on lower tween level. Most of the Hitachi-specific microscope accessories were stored with the Hitachi SEM (including the old vacuum pump), however sorting through accessories to determine what cannot be used with the SEC SEM-EDS is ongoing.

 

The new SEC SNE-4500M SEM-EDS and components were assembled in the Microscopy Lab on the existing SEM lab bench.

  • Installation was performed with help via correspondence with Jon Lechich from NanoImages. He shared both Bruker and NanoImages installation guides, which offer considerably more information than the User Guides. Documentation of the installation process is ongoing.

  • Components of system are: SEM, SEM control unit, EDS, EDS control box, vacuum pump, air compressor, and computer/monitor

  • User guides are on Confluence. These are left in a fairly complete state, but should be viewed as works in progress. It is not recommended that users operate the SEM before without training and supervision.

The SEM-EDS sits on an anti-vibration mount attached to the tabletop:

  • Four 75-lb capacity McMaster-Carr helical coils are screwed between the tabletop and a steel plate (18x18", 3/4-inch thick).

  • The SEM sits on four cork pads and two strips of rubber on top of the steel plate.

  • SEM is secured with strap around steel plate (this should be loosened during operation of SEM).

 

Figure 1. Microscopy Lab workstation with SEM-EDS components and sputter coater.

Figures 2 and 3. Side view and closeup of anti-vibration components.

 

Tested & troubleshot SEM-EDS imaging capabilities:

  • Tested image and power stability with thrusters down and in mild seas during transit (0.5-1.0 m heave, 0.5-1.5° rolls).

  • Power stability was generally good, however only the SEM (this includes both boxes and the vacuum pump, which all draw power through the same plug) and Bruker EDS Scanning Control Unit (SCU) should be connected to the UPS. Any more, and the UPS will be over capacity.

  • The imaging capability is performing well at intermediate (3) scan speeds; on a scale of 1-5 with scan speed 1 being the lowest resolution. See Figures 3-5.

  • Images experience distortion at high resolution scan speeds (4-5) and high magnifications (above ~5000x). See Figures 4-5.

  • Engineers gave advice on how to improve image stability: Andrew Howard suggested changing to higher capacity helical coils, and John Van Hyfte suggested sending out accelerometers (formerly used during APCT-3 development) to measure the forces experienced by the SEM at sea. Higher capacity helical coils are on order, to be swapped out at a later period in time.

  • Two potential other stage options from NanoImages were explored as possible alternatives: lower-level manual stage and higher-level piezo stage.

  • We tested out remote capabilities with Jon Lechich from NanoImages using TeamViewer and WhatsApp audio simultaneously. TeamViewer requires a high degree of internet stability, but otherwise the system seemed to work well.

 

Figure 3. Forams imaged at 500x and scan speed 3. Images taken onsite.

 

Figure 4. Calibration stub with copper coated spheres imaged at 4000x with different scan speeds. Images taken onsite.

 

Figure 5. Nannofossils on the surface of a foram, imaged at 4000x with different scan speeds. Some distortion at speed 4 and notable distortion at speed 5. Images taken onsite.

 

Tested EDS functionality:

  • Installed license

  • Calibrated EDS detector using PELCO standard stub

  • Tested EDS analyses on a carbon-coated thin section: object scanning works well, however mapping is subject to the same motion-related image stability issues as imaging. In general, total mass percents seem a bit low (80-90% totals). Jon Lechich from NanoImages suggested that this is a typical result, however Luan is in correspondence with Bruker to see if this can be further optimized.

 

SEM Uploader status:

  • The EDS attachment on the new SEM creates a variety of new data formats for hardrock and mineral composition

  • James Brattin has begun coding for the new SEM-EDS uploader

  • The new application will not be done before the beginning of X397

  • Old SEM Uploader is not compatible with new SEM-EDS images and data files

  • New SEM-EDS files must be be uploaded to Data1 for the time being

Leica sputter coater:

  • The Leica sputter coater was briefly stored, and then reinstalled. It was working well in carbon mode. For a good carbon coat for EDS, on the order of 10-15 flashes should be used. This means that a double thickness of carbon thread will have to be exchanged for every 1-2 times the carbon coater is run. When running a coating process, it is useful to place a small slip of white paper on top of the stage (peeking out from underneath the sample) so that the user may observe a distinct and visible light gray "shadow" where the carbon coat has laid down. Alternatively, the user can do a thinner carbon coat, then test to see if the sample experiences charging under the electron beam. If so, cease SEM and EDS work and re-coat the sample. EDS results run on a charged sample should not be trusted.

Closeup

Only one closeup photo was requested.

General Photography

Weekly Family and Friends photos were collected from various sources. Several headshots were taken for SIEM and Entier crew. 

Tshirt logo, 40 dark transfer paper and 20 light transfer paper were used

Items Ordered

Four (4) 125 lb capacity Horizontal-Force Bolt-Down Vibration-Damping Mounts with Unthreaded Hole, Part No. 62225K13

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