10 exam-style questions with answers and explanations, straight from our 1,030-question bank. Tap an answer to check yourself. When you're ready, take the scored version in the free practice test.
The CLSO exam has 100 questions and runs 3 hours.
These 10 free CLSO questions are organized by exam domain, so you can see how each part of the Certified Laser Safety Officer blueprint is tested. Reveal the answer and explanation under each question.
A pulsed laser is adjusted from 200 Hz to 50 Hz while its average output is maintained at 2.0 W. Pulses within each setting have equal energy. The beam dump is rated for 5 W average power and 30 mJ per pulse at the actual wavelength, pulse duration, and spot size. How does the new setting compare with the dump's ratings?
Correct answer: C - 40 mJ per pulse; the pulse-energy rating is exceeded.
Six hours after an unprotected exposure to scattered 248 nm excimer-laser light, a technician develops gritty pain, tearing, and marked light sensitivity in both eyes. Which tissue and injury mechanism best explain this pattern?
Correct answer: D - Photochemical injury to the corneal epithelium.
An extraction system captures emissions effectively at a polymer laser-cutting process and returns the air through a HEPA unit. The filter passes its particulate-integrity test, but monitoring identifies a hazardous process-generated vapor in the returned air. Which equipment change addresses the contaminant the existing filtration stage is not removing?
Correct answer: A - Add gas-phase treatment validated for the identified vapor and concentration.
The maximum ocular exposures evaluated for two separate alignment modes are 2,000 times the applicable MPE at 532 nm and 600 times the applicable MPE at 1064 nm. Only one mode operates at a time. The task requires visible-light transmission (VLT) of at least 35%. All four eyewear models fit properly and withstand the assessed beam loading. Which model satisfies the requirements for both modes?
Correct answer: A - OD 4 at 532 nm; OD 3 at 1064 nm; 45% VLT.
During an LSO-approved open-panel alignment, the operator cannot reliably resolve the spot on a fluorescent beam card through the required eyewear. Output is already at the maximum permitted by the alignment procedure, and all prescribed beam and access controls are in place. What is the best way to obtain usable visual feedback?
Correct answer: C - Observe the card by remote video while retaining the prescribed controls.
A Class IV laser product manufactured in 2022 loses main electrical power unexpectedly for eight seconds. Power returns with all interlocks satisfied. In a compliance assessment under 21 CFR 1040.10(f)(10), which restart behavior meets the requirement?
Correct answer: B - Emission remains inhibited until the operator performs a manual reset.
A production laser marker is classified as Class 1 with its enclosure closed. It contains a Class 4 laser, but inspection confirms that the housing and interlocks function correctly and accessible emissions remain within Class 1 limits. Production does not require opening the housing. Which operating decision is supported by these findings?
Correct answer: C - Continue normal production; use separate service controls when hazardous internal emission becomes accessible.
At an ocular exposure position, 16 identical laser pulses each deliver 4.5 µJ/cm². The applicable evaluation establishes three limits: 12 µJ/cm² for an individual pulse, 60 µJ/cm² for the complete burst, and 6.0 µJ/cm² per pulse after the required repetitive-pulse correction. All values use the same averaging aperture. Which decision follows from applying all three criteria?
Correct answer: B - Reduce the burst exposure; its total exceeds the burst limit despite acceptable individual pulses.
After a suspected specular exposure to a 1064 nm beam, an employee reports a new small missing patch just off the center of vision. A quick visual-acuity check remains 20/20, and the eye is painless. The laser has been secured. What should take priority?
Correct answer: A - Arrange urgent ophthalmic assessment without waiting for exposure reconstruction.
A photodiode power meter gives nearly the same reading at three successively higher laser output settings. The full beam falls on the detector, and the wavelength setting is correct. With a calibrated attenuator inserted, readings corrected for its transmission rise with each output setting; a second attenuation level confirms those corrected readings. The original plateau most likely reflects:
Correct answer: D - Nonlinear response caused by detector or meter saturation.
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