VIRMOS MMU activities in Milan

VIRMOS MMU activities in Milan

The VIRMOS MMU is one of the main contributions of IFCTR to VIRMOS.
MMU development and testing activities in Milan began in 1997, and continued until April 2000 (when the MMU passed the PAE (Preliminary Acceptance Europe) review with ESO, and July 2000 when the hardware was sent to Paranal where it has been successfully installed

Such activities included

Future activities will include The remainder of this page gives a quick visual idea of the hardware set-up at IFCTR.
(full size pictures can be viewed clicking on table cells)

Laser cutting machine

[JPEG: laser machine ] [JPEG:laser closeup]
A view of the StencilLaser cutting machine, its control electronics and the MMCU computer with all parts clearly labelled. A close-up view of the StencilLaser as originally delivered.
We modified this arrangement bringing to the side of the front panel the controls used to operate the exhauster, and adding springs to the mask clamps instead of the original air pressure system which was stretching the material too much.
The additional devices (exhauster, chiller, air pressure supply) were lodged behind the door shown in background.
[JPEG: workshop with SC] [JPEG: machine under hood]
A top view of the StencilLaser cutting machine, its control electronics and MMCU computer
The MHCU computer is also visible in the background, and the SC in the front.
To avoid contamination in our quite dirty environment, the cutting machine was lodged under a laminar flow hood, shown here partially open behind some members of the MMU team (from right to left, G.Conti, E.Mattaini and L.Chiappetti)
[JPEG: G.Conti at console] [JPEG: G.Conti smoking at console]

Invar procurement

[JPEG: invar roll] the picture shows the rough Invar roll (weight 1229 kg) once delivered by Krupp VDM GmbH

The roll has been delivered to CEM Lavorazioni Elettromeccaniche Srl, which has cut it into 34 x 45 cm sheets, painted them in black with a dull paint (TGW8608) and covered the upper site with an adhesive plastic protection. They delivered back to us 4640 sheets of approved quality, 350 rejected sheets, and 120 of intermediate quality.

A good deal of the latter two categories have been used for tests in Milan, and few of the good material for manufacturing of masks required for VIMOS integration at OHP. The rest has been delivered to ESO, representing a supply for at least 2 years of operation (about 4200 sheets).

Storage Cabinet

[JPEG: SC view] [JPEG: SC detail]
The left picture gives a full view of the VIMOS Storage Cabinet (SC) mounted on its table, and with the dust-protective doors opened.
The SC contains four (colour coded) sections, two on each side, one for each VIMOS quadrant

The top picture shows a closeup of the SC barcode reader, and the detail of the 100 mask slots in a quadrant. The white section is used as background for the mask bar code used for identification.
The barcode reader is connected by a serial cable to a pivot holder on the ceiling (such that it can be moved to either side of the SC) and from there to the MHCU computer where the MHS software runs.
The barcode is used to search a mask in the SC in support to the MHS software load and discard functions.

IC Robot

[JPEG: Robot view, annotated] The picture on the left gives a front view of the IC Robot with the IC holder (IC box) mounted onto it, and all parts clearly labelled.

The bottom left picture shows a side view from the back side of the IC holder. The MHCU computer (to which the robot and the associated barcode reader are connected by serial cables). appears in the background.

The bottom right picture shows a side view from the front side of the IC holder. A mask is visible on the mask stand, and the MHCU computer in foreground.
The blue arm protruding towards the top holds a photocell, which detects obstructions to the movement of the IC box (like the IC box cover, or an half-inserted mask)

The function of the IC robot is to raise, under computer control, the IC box in order to position one of the 15 slots of one of the 4 ICs at the level of the mask stand, to allow manual extraction or insertion of a mask, to be identified by the barcode reader.

These operations are supported by the MHS software load and unload (IC preparation) functions. The mask stand is also used to identify freshly manufactured mask in support to the store function.

In all pictures the IC box is empty : in normal operations it shall contain the 4 Instrument Cabinets built in Naples.

[JPEG: Robot side view] [JPEG: Robot view with stand and clamp]

Computers and software

The operation of MMU is supported by three identical Dell Optiplex GX1 PCs (visible in the pictures above) with Windows NT. Part of the s/w was supplied by third parties (mainly LPKF AG) while the Mask Handling Subsystem (MHS) was developed by us under Microsoft Visual Basic.
The function of the three computers is as follows :
  • The MMCU (Mask Manufacturing Control Unit) controls the StencilLaser machine via the LPKF StencilMaster s/w and our front end CutManager. It receives files describing the masks to be cut in LPKF proprietary format from the MHCU.
  • The MHCU (Mask Handling Control Unit) is connected to the IC robot and to the two barcode readers. It runs the MHS software to control the sequencing of all operations. In particular it receives jobs (orders) via ftp from the vmmcs module of the VIMOS software, and uses LPKF CircuitCam s/w to convert the files describing the masks to be cut in LPKF proprietary format for the MMCU.
  • The spare computer is normally in cold redundancy, and is occasionally used to operate the roughness meter, to perform other ancillary chores, and as development system.

Quality check activities

[JPEG: Roughness meter view] The picture shows the Taylor-Hobson (TH) Talysurf roughness meter installed at IFCTR (the white and blue box on its granite stand). The knife probe is indicated by the label and extends to taste a small quality sample held in the vice provided by us

Roughness data can be read on the roughness meter display, or acquired on the spare computer for further analysis and display using TH software

Further quality checks (about roughness and cut quality, and also about slit widths) have been done by visual inspection using a microscope

Further checks about the position reproducibility of the cuts have been done cutting pinhole masks and measuring their positions at external sites or at LAS.
The positioning accuracy of the StencilLaser motion system has been verified comparing the readout of its Heidenhain rule with measurements with an HP laser interferometer lent to us by CNR institute ITIA


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