The standard specifies performance requirements according to the Class of the laser product and the accessible laser radiation. Note that, where the standard requires a particular
performance feature, the feature must be readily identifiable as such on the product. Failure to properly identify required features may lead to difficulties in determining product compliance. The applicability of many requirements depends on whether the product is a laser, or a laser system (1040.10(b) (19),(23)).
A protectivehousing (1040.10(f)(l)) is required for all laser products. The protective housing must prevent human access to laser radiation in excess of the limits of Class I (and collateral radiation in excess of the collateral radiation limits) at all places and times where and when such human access is not necessary in order for the product to accomplish its intended function. The manufacturer must be prepared to justify the necessity of human access to laser radiation greater than Class I limits. If the purpose of the laser system is to generate a laser beam, the justification is self-evident. In other cases, a detailed analysis may be required. Generally, a protective housing must be contiguous. The most common difficulties with protective housings have been human access to laser radiation through cooling vents, or through a poor fit between sections of a protective housing. A protective housing must be sturdy enough to prevent access caused by bending or warping as the product ages.
Safety interlocks (1040.10(f)(2)) may be required on any laser product. They must prevent human access to laser or collateral radiation that exceeds the limits of Class I and Table VI84 when a protective housing is opened during operation or maintenance, and human access to the interior radiation is not always necessary during such operation or maintenance. (Note that if the housing must be opened during operation and it is necessary to have access to the interior radiation, the level of the interior radiation must be considered when classifying the product, i. e., the classification is determined by the interior level, if it is higher than the exterior level. If the intermittent access to laser radiation occurs only during a maintenance procedure, it does not affect the class of the product.) If access to the interior radiation is sometimes needed, the interlock may be defeatable and the housing must be so labeled. Safety interlocks need not prevent access to interior radiation otherwise accessible only during service.
Safety interlocks to protect from Class IIIb or IV levels must also be redundant or failsafe; if fail-safe, they must either prevent opening the housing in case they fail, or they must be incapable of failing in a mode that would permit access. Defeatable safety interlocks must provide a visible or audible indication of defeat; further, it must not be possible to close the housing with the interlock remaining defeated. A redundant or fail-safe safety interlock is also required if the failure of a single interlock would allow access to laser radiation in excess of the accessible emission limits of Class II to be emitted directly through the opening created by removal or displacement of the interlocked portion of the protective housing.
A remote interlock connector (1040.10(f)(3)) is required on all Class IIIb and IV laser systems. The purpose of the remote interlock connector is to permit the user to connect a remote barrier interlock, emergency stop switch, or similar device. The circuit must be designed such that, when the terminals of the connector are open, human access to laser radiation is prevented. The electrical potential across the connector terminals must not be greater than 130 volts rms.
A keycontrol (1040.10(f)(4)) is required for Class IIIb and IV laser systems in order for the user to prevent unauthorized operation. The key must not be removable in the “on” position.
An emission indicator (1040, 10(f)(5)) is required on Class II, IIIa, IIIb, and IV laser systems. The indicator can be visible or audible. On Class IIIb and IV laser systems, the indication must precede emission by a length of time sufficient to allow users and others in the area to recognize that the product has been energized so they can avoid exposure. Depending on the action required and the level of laser radiation involved, the time needed can vary considerably; typical values are in the range of 2-20 seconds. Emission indicators must be duplicated on lasers (heads) and operation controls if they are capable of being separated by greater than 2 meters.
A beam attenuator (1040.10(f)(6)) is required on Class II, Ilia, Illb, and IV laser systems. The beam attenuator is a mechanical or electrical device such as a shutter or attenuator that blocks emission. The beam attenuator blocks bodily access to laser radiation above Class I limits without the need to turn off the laser. The beam attenuator must be available for use at all times during operation. Power switches and key controls do not satisfy the beam attenuator requirement. Manufacturers may apply for approval of alternate means of providing this protection if a beam attenuator is inappropriate to the product.
Operating controls (1040.10(f)(7)) on a Class II, IIIa, IIIb or IV laser product must be located such that it is not necessary for the user to be exposed while manipulating them. Viewing optics, viewports, or display screens (1040.10(f)(8)) may not provide human access to laser or collateral radiation in excess of the limits of Class I and Table VI85 during operation or maintenance. If the viewing optics employ a shutter or variable attenuator, the shutter or attenuator must be fail-safe; that is, it must be designed such that, upon failure, it is impossible to open the shutter or vary the attenuation. Viewing optics include such devices as viewports, windows, microscopes on welding and drilling devices, and operating microscopes on surgical lasers. Attenuation may be total, or it may be partial as with a filter. Acceptable designs may prevent laser operation until the attenuator has moved into position. Service instructions must include instructions on procedures to avoid hazardous exposure through viewing optics.
A scanningsafeguard (1040.10(f)(9)) must prevent emission in excess of the limits of the class of the product. For Class IIIb or IV laser products that operate in both scanned and unscanned modes, the scanning safeguard also must prevent emission in excess of the limits of the class of the scanned laser radiation (and whose failure would result in emissions exceeding Class IIIa). Scanned laser radiation is laser radiation that is moved in translation or by changing direction. A scan-failure safeguard must have a reaction time short enough to operate before levels of a higher class are emitted; it is possible to achieve this performance by means of a high inertia scanner in conjunction with an electromechanical shutter.
A manualreset (1040.10(f)(10)) is required on Class IV laser systems manufactured after August 20, 1986. It must prevent automatic restart after an interruption due to remote interlock activation or from an interruption for more than 5 seconds due to unexpected loss of main electrical power.