Specifications

Interfacing Diamond Lasers to Systems

part of an interlock system. It can provide up 50 mA of current at

5 VDC and is on as soon as the AC power is applied. Note that if an

over-current or over-voltage situation occurs, the DC supplied must

have the AC input power turned off and then back on to reset the DC

supply and also reset the +5 V logic voltage

RF Power Supply

Control of the laser is performed through the DB25 connector on the

RF power supply. Two inputs are required to operate the laser, and

four outputs are available for monitoring its function. There are, in

addition, two analog outputs that are useful for maintenance

purposes only.

The RF amplifier is enabled by connecting Pin 3 to Pin 16. This is

the preferred signal to use for the water flow interlock and should

also be connected to safety interlocks.

Laser modulation is enabled by driving Pin 7 to a TTL high level

with respect to Pin 20. A differential line driver such as an

AM26LS31 is suitable for this. The laser is on whenever the line is

high and off when it is low. Laser “On” times, referred to as pulse

widths, can be any length less than 1000 µs, although the actual laser

discharge may not respond to very short pulse widths. Incoming

pulse widths longer than 1000 µs will be automatically limited by

the RF amplifier. In addition, the duty cycle of pulsing must not

exceed a maximum (depending on the laser model). The RF ampli-

fier will automatically limit duty cycles. If either the commanded

pulse width or duty cycle exceed the limits, the amplifier will issue

a warning signal.

The RF amplifier provides output signals to monitor its performance

and warn of potential problems. These outputs are to be interfaced

to a differential line receiver such as an AM26LS33, and are:

Digital Reflected Power (Pin 8+, Pin 21–)

This signal goes high when the laser is operating correctly. In the

case of a problem, it will change state with the laser modulation. It

should therefore be monitored by the system control, with a warning

message issued if it drops out when the laser is running. The control

should wait 100 milliseconds after modulation starts to monitor the

reflected power to allow transients to dissipate.

Digital Forward Power (Pin 9+, Pin 22–)

This signal is synchronized with the modulation when the laser is

operating correctly. If it stays high during laser operation, there is a

problem with the RF amplifier. The system control should issue a