Hamburg - Opera Collaboration Meeting - June 2004

Fiducials & labels

F.Laudisio,G.Romano,C.SirignanoSalerno Emulsion Group

Since we will have 200000 bricks and 57 plates per brick we will need (18+6) digits, then a parity check on 0-1. This grid wouldl be also used for CS films and they will undergo the same brick plates’ gridding procedure.

ECC ID(e.g. 175 797)

Plate ID(e.g. 45)

10

50 to 100 m

IntroductionIntroduction

One or two lines

Set-up

We studied how to realise the image and transfer it to the emulsion film.

We tryed two possible solutions:

1) Optical fibers + LCD dispaly

Light source

Thick optical fiber (3-6 mm)

LCD 128 x 128

They could be also in front of LCD workingas a reflector

Optical conduit

EmulsionLense

Liquid chrystals display

2) High luminosity LEDs + lenses

“... Take a LEDs’ pictureon the emulsion...”

The solution adopted now is the following:

PCParallel port

SoftwareIC LEDs

The IC we use is a LED display driver (M5450) and the serial data transfer from the data source to the display driver is accomplishedwith two signals, serial data and clock.

One IC can control up to 33 LEDs.

We have realised by ourselves a dedicated software for the data flowand a test-circuit of 24 LEDs.

in details...

Control module

InputOutput

IC-M5450IC-NE555:To regulate exposure times

Trimmers:To regulate LED brightness

LEDs module

LED diameter is 3mm

Diffusor lense + 1mm holes on eachLED

There have been ralised two tubessliding one ino the other to focus our image on the glass top surface

Objective

We used a standard 50x objective from a Canon camera.

Users’ interface

Whith this simple interface it is possible to enlight the right LEDs.

It is possible to increase automaticallythe sheet number (from 1 to 57) or to have a test image.

21

Exposure time

Thanks to an array of 11 100kW resistors, one commutator and two different capacitors, we can set exposure time authomatically and we have been able to evaluate emulsion sensitivity.

It turned out that working with a separate power supply of 5V a 1s exposurewill be enough to have round dark dots (75 m diameter).

In order to measure LEDs’ brightness oneby one we used a photo-resistor and weset the proper resistence value for eachLED using trimmers.

Brick & Sheet Id

Then we performed a test exposure with Brick number fixed and Sheet numberraising from 1 to 57.

We have chosen two exposure times ( 0,5 s and 3,3 s).

Results looks like really promising...

3,3 s0,5 s

Gridding

We can realise a reference grid of 3 or 4 single dark dots with separatetubes and objectives fixed under the table.

Reference corner

It will be possible to authomathize gridding procedure using a robotsimilar to the BAM’s piling machine, it will give us a reasonable gridding precision.