VSM7xD – Coating of Mirrors
The digital combination transducer VSM (Pirani/cold cathode) measures absolute pressure from atmospheric pressure to ultrahigh vacuum
During the optical coating of mirrors for laser resonators the typical process pressure lies above 2e-3 mbar.
Challenge
A suitable vacuum transducer must be able to monitor both, process pressure during the coating as well as the available minimum pressure of e-6 mbar in the vacuum chamber. Our client used to work with a Pirani/cold cathode combination gauge, the cold cathode monitoring minimum and process vacuum. However, the continuous operation above e-3 mbar resulted in early wear and tear of the sensor.
Solution
In the VSM transducer the Thyracont Pirani activates the cold cathode only below very low pressures. Further the transition between the two sensors can be configured according to the applications requirements. This way we achieved that the entire coating process is now monitored by the Pirani. The cold cathode is saved because it is active only when the appliance pumps down to minimum pressure. The availability of the coating plant improves significantly.
Benefits at a Glance
Specifications
| Weight | 1.1 kg |
|---|---|
| Dimensions | 25 x 16 x 9 cm |
| Gas dependency | depending on gas type |
| Measurement range mbar | 1000 – 5e-9 mbar |
| Measurement range Torr | 750 – 5e-9 Torr |
| max. overload | 10 bar abs., 16 bar abs. with CERT31P |
| max. overload with CERT31P | up to 16 bar abs. |
| Accuracy | 1000 – 10 mbar: approx. 30 % f. r. | 10 – 2e-3 mbar: 10 % f. r. | 2e-3 – 1e-8 mbar: 25 % f. r. |
| Repeatability | 10 – 1e-2 mbar: ca. 2% f. r. | 1e-2 – 1e-8 mbar: ca. 7% f. r. |
| Materials in contact with vacuum | Edelstahl 1.4307, tungsten, nickel, glass, molybdenum, Al₂O₃ ceramic |
| Filaments / anodes | Molybdenium |
| anode voltage | < 2.5 kV |
| Response time | 50 ms (switch-on cold cathode |
| Operating temperature | +5…+60 °C |
| Storage temperature | -40…+65 °C |
| Bake out temperature | Max. 160 °C at the flange (voltage supply switched-off) |
| Voltage supply | 20 – 30 VDC |
| Power consumption | Max. 2,5 W, add. 0,8 W f. EtherCAT/ Relais/ LCD, add. 1.6 W f. Profinet |
| Output Singal SL | 0 – 10 VDC, min. 10 kΩ, measuring range 1,82 – 8,6 VDC, log. (Default) except EtherCAT, Profinet |
| Serial interface | RS485: 9.6 kBd to 115 kBd, 8 databit, 1 stopbit, no parity |
| Electrical connection | SubD 15pole, male |
| Article Number (choice of vacuum connection): | DN 25 ISO-KF (VSM77), DN 40 CF-F (VSM79), DN 40 ISO-KF (VSM78) |
| Dimensions | 139 x 69 x 48 mm (VSM77) |
| Protection class | IP40, IP54 mit connector XB15SL05 |
| Weight | 555 g (VSM77) |
