Frequently Asked Questions
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Where can I get a laser warning light that automatically turns on and off with my laser?
This type of warning light is not sold because most laser manufacturers do not provide an "output" signal that can be used to turn a warning on and off. We use an interlock system to control the laser warning light. When the interlock is set, the warning illuminates. The interlock system then gives "permission" for the laser to start. The result is a situation where the laser cannot energize unless the warning is on. It is true that warning can now be illuminated without the laser actually being energized, but from a safety standpoint it doesn't matter. A warning lamp indicates that there is a potential for exposure because the laser has been given permission to run.
My laser turns on and off with a key. I don't know what you mean by the term "interlock".
The key is one of the "on-off" control functions available, but every commercial class 3B and class 4 laser sold in the United States will also have an external interlock connection capability. The interlock connection is a terminal board or connector that comes as a feature on your laser. It needs at least two of its pins "shorted" together in order for the laser to start. The connector usually comes from the manufacturer in a "shorted" state. This is unfortunate, because many people place their laser in service without ever considering the installation of proper safety interlocks.
Who mandates the interlock connection?
Mandates from the U.S. Food & Drug Administration (FDA) Center for Devices and Radiological Health (CDRH) are released as federal code in Title 21 of the Code of Federal Regulations (21CFR). Chapter 21CFR1040.10 lists the performance standards for the manufacture of laser products. Information pertaining to the laser housing interlocks, remote electrical interlocks, labeling, and power classification are found in that chapter. Chapters 1000-1005, 1010, and 1040 are collectively known by the acronym FLPPS, which stands for Federal Laser Product Performance Standards. All federally mandated regulations are provided free of charge to the public. They can be viewed and printed from the internet. A searchable database can be found at:
Do I have to use the laser interlock connection?
No, you don't have to use it, but it is mandated to be there for your use. There are many other ways to create a laser safe environment. You can interlock power "mains" or simply use a shutter to secure the laser output. The ultimate goal to keep in mind is the rapid safe drop in emitted power to a level below the maximum permissible exposure (MPE) level. Remember, MPE is the level of laser radiation to which an unprotected person may be exposed without adverse biological changes in the eye or skin.
I am afraid that my experiment will be ruined if the laser is tripped off by an interlock. How can I avoid nuisance trips?
A properly designed interlock control system can facilitate long term experiments of weeks, months, or even years without a single "nuisance" trip. Our defeatable access control systems use the following key features:
- Audible and visual indications of interlock override state with audible countdown timer and end of timeout alarm, which greatly reduces the risk that a door will be held open beyond the permitted override condition.
- Positive access control, either by magnetic lock, electronic mortise latch, or electric strike. This ensures that a user (or non-user) will not accidentally open the interlocked door before initiating a timed override condition.
- Automatic exit override can be implemented in any of our systems with the installation of a floor pressure pad or motion detector.
- Intelligent access timing features that permit early cancellation of the interlock timer based on entry actions.
In a properly designed system, the only conditions that will trip the laser interlock are:
- A system power failure. (Lasers would have tripped anyway upon loss of power)
- A real safety violation. (The very reason we interlock)
Can I purchase a defeatable access control system without a magnetic lock?
Yes, if you really want the LSS-2385 system without a magnetic lock, we can provide the kit with only the keypad, interior crash (E-Stop), and push-to-exit module. Be forewarned that the risk of nuisance trips will increase significantly without some form of positive access control.
Why don't you have the illuminated safety signs?
We don't see the need for a large illuminated sign. You will already have a DANGER sign on your door if you are setting up a lab that is compliant with ANSI Z136.1. There has never been a requirement for an illuminated sign. Our LSS-2380 warning strobe meets and exceeds the ANSI warning requirement by providing both audible and visual indication of laser interlock status. It is effectively a tri-lume indicator that shows laser on, laser safe, and interlock system crashed states. That being said, keep checking our web site because we have something in the works to meet this frequent request. When released, it will have enhanced features different from what you've seen in the past. It will also be backward compatible to our LSS-2380 series wiring protocol.
Could you build us something that senses laser current or light output to make a warning light turn on and off automatically?
It could be designed and built, but we would never sell it. There are too many variables that could go wrong. The sensor would need to be specially calibrated for each laser system. What if the sensor burns up? It is better to stick with the failsafe method of having an interlock system control the warning and laser.
Do you still have questions?