Safety Interlock and Process Control Shutters

These shutters are designed for high optical power and damage thresholds, but with lower emphasis on speed.

The Safety Interlock Shutter is normally kept open for long periods of time, closing only for breaches in the safety system or at the end of an experiment.

The Process Control Shutter is used at frequent intervals, allowing equipment to move or change in between optical exposures. An example would be laser cutting. At various points, the shutter would block the laser to allow table repositioning and cutting to resume.

All Safety Interlock and Process Control Shutters are failsafe and close upon power loss. They are not dependent on gravity to close.

Switching speed requirements for safety and process applications are moderate. The flexure technology used in these products offer inherent fast switching without developing large heat loads in the electromagnet.

Position sensors are on most of the models, providing a safety or process circuit with verification that the shutter did indeed open or close as it was instructed to do from the power circuit.

These position sensors are completely independent of the power circuit. They audit the physical movement of the flexure blade, with either solid-state opto-interrupters for smaller apertures, or mechanical micro-switches for larger apertures.

The solid-state sensors are powered from regulated 5 VDC at about 20 mA current budget. There are two output leads which yield a logic hi or lo depending on shutter state.

Our CX2450B controller series provide the 5 V and offer the output conveniently on a terminal strip at the rear of the controller.

The output signals are logic ready TTL totem pole outputs, able to drive up to about 5 mA. This signal can be used to control software or to drive power electronics for warning light illumination.

The mechanical micro-switches provide contact closure for the open and closed states. There are two leads for each switch. Typically switches are operated at 5, 12, 24 VDC at a few tens of mA, but are rated for use at several Amps. Contact resistance is less than 5 ohms with cable loss included.

Many of these models are driven with user-built circuitry. Switching speed is very dependent on the circuit, with more advanced circuits providing faster speeds. In general, all models close in less than 50 msec, with an approximate rule of 4 msec per mm of aperture diameter.