Autostart

General description
Autostart window
The Autostart state machine
Additional Autostart parameters
Appendix 1: list of states (returned by ast?)

General description

Most Vue series controllers (with the exception of the Vue-MC) support stand-alone operation. When this feature is enabled the controller automatically performs a built-in procedure at power up, designed to initialize the laser to some user-specified operating state. The details of this procedure will vary slightly from one type of controller to another. If temperature servos are present, they are turned on and stabilized before the laser is turned on. In some cases (DPSS and HCT controllers), the controller provides a “warm up” step wherein the laser initially comes on at a modified current until a specified time has elapsed. Safety (CDRH) time delays are optionally provided. When these preparations are complete, the laser is turned on and brought to its operating point, which is then maintained indefinitely.

This capability, which we call Autostart, allows VueMetrix controllers to operate without any interaction from a PC or other host computer. This section explains how to set up and use Autostart.

Autostart window

When a Vue series controller ships from the factory, Autostart is disabled. To enable it requires a one-time initial set up with a host PC, conveniently done with WinVue's Autostart window. Please note that this window is generic, whereas specific products implement different sets of features. When a feature is unavailable on your system, the corresponding entry field in WinVue appears grayed out.

Enable on power-up

Check this box to tell the controller to perform Autostart the next time power is turned on. This does not affect in any way what the controller is doing right now.

Execute from beginning

Causes Autostart to execute from the beginning, regardless of what the controller is doing right now. It does not affect what the controller will do the next time it is turned on. This feature is provided for test purposes.

Abort

Stops the Autostart procedure immediately. This does not return the controller to the initial (power-on) state, but rather preserves the operating condition that existed at the instant the button was pressed.

Constant power operation

Click this box to use constant power control for the laser operating mode. Uncheck the box to operate the laser at a constant current. Note that some systems may include a warm up state, which is always at a constant current.

Operating current

Type here the desired laser operating current. If the “Constant power operation” box is checked, this value is irrelevant.

Operating power

Type here the desired laser output power. If the “Constant power operation” box is not checked, this value is irrelevant.

Warmup current

Type here the current used to warm up the laser. This applies only during the warm up process and does not affect the final operating point.

Low temperature limit

Type here the minimum temperature at which laser operation is permitted. Below this value the controller performs a special “warm up” procedure. The warm up procedure continues until the temperature rises to two degrees above this limit, at which point normal operation is initialized.

High temperature limit

Type here the maximum temperature at which laser operation is permitted. Above this value the laser current is shut off, and the controller waits for the temperature to decrease. When the temperature is two degrees below this limit, normal laser operation is resumed.

CDRH compliant

Check this box to force the controller to wait for at least 30 seconds before applying current to the laser. When this box is not checked, Autostart turns on the laser as quickly as possible after the power is turned on. Some systems still require a delay for temperature control.

Warmup CW

Check this box to force the controller to operate the laser continuously (CW) during warm up, even though the final operating mode may be pulsed.

The Autostart state machine

Autostart is a finite state machine. In the WinVue Autostart window, the list of possible states is presented in a black sub-window at the lower left. At any given instant, the “active” state is highlighted in yellow.

Programmer's note: Under the hood, WinVue obtains the Autostart state by periodically sending the command “ast?” to the controller. The reply, a small integer, is then translated into a human-readable form. The mapping between the integers and the state names varies from one product to another; see Appendix 1.

Disabled

Product: All

The controller was powered up with Autostart disabled. No subsequent Autostart commands have been received.

Standby

Product: DPSS 0.8 and DPSS 3.0

The temperature servos are on but the laser has been turned off using WinVue or a serial command. When the laser is turned back on the Warmup state will be immediately entered.

Waiting temps (or Waiting)

Product: All

This state is entered when the controller is first turned on and Autostart is enabled. It is also entered when “Execute from beginning” is clicked, or the command “as1” is sent on the serial interface.

On systems that feature temperature control (DPSS and HCT) the servos are enabled. The laser is off. Autostart remains in this state until all the temperatures have stabilized. In addition, on DPSS lasers this state is always at least 30 seconds long for safety (CDRH) compliance. On Vue-HCT, this safety delay is a user-settable option.

On systems where there is no temperature control (HC, HCV, HV and MV), the only function of this state is to produce a 30 second safety delay. On all these systems the existence of this delay is a user-settable option. If the optional safety delay is enabled, it only happens once each time the controller is turned on; subsequent restarts of the controller (for example, after a fault reset) skip directly to the Warmup (or Complete on HV) state.

When this state is finished Autostart proceeds, in most cases, to “Warmup.” In the case of HV only, the next state is “Complete.”

Warmup

Product: All except HV

The behavior of this state varies from one product to another.

For DPSS and HCT systems, the laser is turned on at the warmup current and held there for the warm up time. When the time expires DPSS controllers enters the Complete state. HCT controllers, in addition to the time delay, also wait if necessary for the temperature to stabilize. HCT can bypass this state entirely by setting the warmup delay to 0.0.

For systems that can monitor but not control temperature (HC, HCT, MV), this state is only entered briefly. It persists only if the external temperature sensor reports an under-temperature condition. This state is also entered from the “Complete” state when the external temperature reading is too low. The laser diode is turned on at the warmup current until the under-temperature condition no longer exists. From a system point of view, the under-temperature condition suggests the danger of condensation on optical surfaces, and operating the laser diode at some safe (below threshold) current is intended to provide enough heat to raise the temperature of the system without producing light.

On systems with a pulsed option (MV, HCV), the Warmup state can be set to operate always CW (with pulsing temporarily disabled).

On all products, when “Warmup” is finished Autostart enters the “Complete” state.

Cooldown

Product: HC, HCT, and MV

This state occurs in the “Complete” state if the external temperature sensor reports an over-temperature condition. The laser diode is turned off until the condition no longer exists, in which case the “Complete” state is entered once again.

Complete

Product: All

The laser operates at the preset power or current. The temperature servos, if any, are on.

Fault

Product: All

The laser has been shut off because of a fault condition. When the Clear Faults button is pressed in WinVue, or the “cf” command is sent on the serial interface, the controller will start the Autostart procedure (if enabled) as though it were initially turned on.

Aborted

Product: All

The Autostart procedure has been aborted. The moment the Abort button is pressed or “as0” is sent through the serial interface, the controller stops the Autostart sequence. It does not “clean up” the state of the controller by turning off the laser or the temperature servos. To run Autostart again it must be started from the beginning, either using the “Execute from the beginning” button on WinVue, sending the “as1” command on the serial interface, or cycling the power.

Pre burn-in

Factory only.

Burn-in

Factory only.

Additional Autostart parameters

Temperature set points

On systems with one or more temperature servos, Autostart activates these servos and waits for the temperatures to stabilize before turning on the laser. All WinVue controllers store the temperature set points in non-volatile memory, regardless of whether Autostart is used or not. These set points are adjusted using the Main TEC Control window, not the Autostart window.

Pulsed operation

On systems that support pulsed operation, Autostart sets the pulsed parameters to their last known values. These parameters, which are manipulated through the “Pulsing” window, include pulsed/cw operation, internal/external triggering, repetition rate, and pulse width. All WinVue controllers store these values in non-volatile memory, regardless of whether Autostart is used or not.

Appendix 1: list of states (returned by ast?)

¹On HV, the warmup and cooldown states exist in the definition of the serial interface but do not actually occur.