The operation of an SM-Series module is remotely controlled through two interfaces. In order to simplify the task of the user, a module is controlled using simple commands such as DC-voltages and single digital lines.
Despite high-pin count connectors, this choice to provide a straightforward interface should be time-efficient during rapid prototyping phases.
This application note reports several ways to control an SM-Series module over its digital interface.
Since this module is fully compatible with the SMB00 module, please visit the relevant product page.
In order to provide remote control of the modules, all SM-Series boards have their digital control lines connected to the respective stack-through header. While some of these lines could be directly controlled by other boards, front panel switches are usually required to implement the simplest commands.
The SMZ120 module allows the user to connect each digital input to a dedicated front panel switch. For this purpose, up to 11 switches are available on the front panel. The connections between the switch and the controlled lines are made using small AND-wired diodes, providing a convenient way to control several digital inputs with a single switch.
Like all SM-Series modules, the SMZ120 is shipped with the schematic diagrams of its electronic circuitry providing all required information for advanced users.
Since the SM-Series modules can not have more than 4 or 5 coaxial connectors on their front panel, these connectors are reserved for RF and specific I/O signals . The remaining signals of the module, such as the digital control lines or the analog inputs, are connected to their respective stack-through header. While some of these signals are used by other boards, the user may need to access an analog or digital I/O using a BNC connector.
The SMZ110 module allows the user to connect an analog or digital I/O to a front panel BNC. Up to 5 BNCs are available on front panel and every I/O of the analog and digital interface can be wired. The connections between the BNC and the I/O are made using small jumper wires. In addition, component footprints are provided to implement passive filters.
Like all SM-Series modules, the SMZ110 is shipped with the schematic diagrams of its electronic circuitry providing all required information for advanced users.
3U/4H front panel not shown.
SMB-Series is a dedicated modular instrumentation for Optical Phase-Locked Loop applications. The SMB-Series modules are designed to operate from several DC-power supplies. Each module has two 50-pin stack-through headers acting as a power bus when several boards are stacked. SMB00 is the interface board used to connect the supply sources to the power bus.
In order to ensure a safe and reliable operation when the stack is powered-up, the SMB00 provides protections against accidental reverse voltage connections and in-rush current limitations. An L-C tank filter is also provided for high-frequency noise suppression. Under-voltage levels are detected by a monitoring circuit that signals a power fault condition both using leds on the front panel and an open-collector digital output.
3U/4HP front panel not shown.
The SMB30 module is an electronic board for use in Optical Phase-Locked Loop (OPLL) applications where the frequency detuning between two laser sources requires tight and quick control.
This board is a PID compensator designed for the piezo actuator of the laser source. In such applications, the low-frequency path is used to desaturate the high-speed loop that controls the fast frequency actuator over a wide bandwidth. The SMA30 is designed to work with the RF Frequency Mixer (SMA10) and High-Speed Compensator (SMA20) modules. While the SMA30 output is able to drive low-voltage capacitive loads, an external piezo driver may be required for high-voltage actuators.
The SMA30 module gives a complete control of the loop filter operation for most demanding users. All analog inputs use differential pairs to avoid ground-loops. The loop polarity is set using a remote control or a local switch and the loop gain is adjusted over 80 dB using either a front panel trimmer or a DC-voltage. For lock-acquisition purposes, the integrator output of the PID can be precisely controlled by the user. A ramp input is provided to sweep the frequency during the open-loop operation and a feedforward input offers a useful control of the fast actuator such as frequency jumps or closed-loop measurements. Additional filter and equalizer stages allow the designer to shape the loop gain more acurately when low-frequency resonances of the piezo actuator can lead to closed-loop oscillations.
Like all SM-Series modules, the SMA30 is shipped with the schematic diagrams of its electronic circuitry providing all required information for advanced users.