Focal 1.5
FOCAL1.5 (acronym of Facility for Optical Calibration At Liège) is a cylindrical stainless steel vessel of 1.1 m3 with a vertical axis and a diameter of 1.5m. Its height is 0.68m for the main part and 0.29m for the cover.
Characteristics
Access flanges in the chamber
For light beam access, thermal fluid transfer and electrical supply, 22 flanges (mainly of 100 mm diameter) are distributed over the whole chamber surface.
Focal 1.5 optical bench
No optical bench is available 
Pumping system
The pumping cycle is divided into 3 steps:
- primary pumping
- turbomolecular pumping
- interseal pumping
This pumping system is designed to reach 5 10-3 Pa after 2 hours of pumping (this value is given for an empty chamber).
Crane
The 10T crane from the clean room is used to install the set-up and specimen in the chamber.
Thermal system
Thermal environments inside the chamber can be simulated by means of dedicated shrouds, fed with nitrogen (liquid or gaseous).
- NITROGEN thermal system :
2 independent thermal channels allow to feed thermal panels. The temperatures can be set in the range from 123 [K] to 353 [K] for the regulation system or 85 [K] for the liquid nitrogen system (each line is equipped with a valve which selects GN2 or LN2 mode).
It is possible to reach higher temperature than 353 [K] with additional heaters glued on the specimen or with infrared lamps installed inside the thermal tent.
The thermal regulation system is designed to avoid oscillations and drift problems.
It warrants performances about +/-0.2 [K] in long term stability.
- Nitrogen connection:
The fluid connection for piping is SS-8-VCR Cajon type.
Data Handling
The data acquisition of Focal 1.5 is organized with Keithley 2701 data loggers with industrial PC’s.
The current sensor capacity is 36 thermocouples (2 wires) or 36 PT100 (4 wires) but the number can be adapted.
The here below type of sensors are usable and readable:
| Thermocouple : T and K type | Resistance 4 wires |
| Diode 4 wires | Cryogenic diode |
| PT100 2 wires | Cernox ([Ω] or [K]) |
| PT100 4 wires | Thermistor |
| PT500 2 wires | Voltage 0-1 [V] et 0-10 [V] |
| PT1000 2 wires | Current< 100 [mA] |
| PT2000 4 wires |
Some display screens are available in the command rooms and in the customer areas. Temperatures, gradients, alarms and warnings can be recorded and plotted.
CSL provides various communication means between the data handling system and the customer:
- The customer can be connected to the Facilities Ethernet network or have a connection to his home base through the public Internet, or through a dedicated ISDN link.
- "Teletesting",i.e the real time monitoring and control of an instrument by a customer remote data logger, can also be implemented.
Clean room and cleanliness aspects
The Focal 1.5 vacuum chamber is located in a class 10 000 (ISO 7) clean room (following US standard:FED-STD-209E).
Offgassing equipment
Focal 1.5 has been upgraded in order to determine the offgassing products from materials and assembled articles to be used in manned space vehicles.
The offgassing consists of maintaining a constant temperature (50 +/- 2.°C) during 72 hours at ambient pressure.
Then, samples of the ambient atmosphere are analysed in order to identify and quantify eventual organic and inorganic volatile contaminants.
