Why not speak to one of the manufacturers. They would have carried out research, and I am sure they would help or point you in the right direction.

Lighting at Work HSG38

Simon - As you mention fluorescent tubes, the cause of the employee's headaches, etc might well be linked to the frequency with which the light flashes to and fro in the tubes rather than the brightness of the light emitted. Tubes generally operate with a frequency of 50 cps (cycles per second), the same as that of the standard power supply. Medical research over 20 years ago found that such oscillations of light can be detected by the human brain - and cause headaches, etc for some people - even though they are not evident to the human eye. This seems to be supported by reports of experiments in offices where significant numbers of employees complained of headaches. They were encouraged to keep simple diaries of when their headaches occurred. When the control mechanisms for the fluorescent lights were changed to give a frequency of 30,000 cps (imperceptible to the human brain) AND without staff being told, the incidence of headaches dropped considerably. I'm no expert on this topic but understand that the devices needed to raise the frequency are neither bulky nor unduly expensive. However, lighting suppliers apparently don't bother providing fluorescent lights which incorporate such devices unless they are specified by customers/clients. This problem may also occur with energy saving bulbs which are essentially mini-fluorescent tubes in a folded configuration for compactness. Please can anyone throw any light (semi-deliberate pun) on this aspect? As an alternative to changing the frequency of the fluorescent tubes, how about experimenting with lights which have halogen or ordinary incandescent bulbs or even a suitably bright array of LED lights? Also, as others have advised, the employee should be allowed to have mini-breaks or at least be encouraged to look away briefly at distance objects at fairly frequent intervals. This is good advice which also applies to prolonged use of computer screens and microscopes, etc. Finally, for the benefit of other forum users faced with similar situations now or in the future, please could you let us know in due course what changes prove to be effective, hopefully, in making the employee's working conditions better for him?

Just wondering how long this gentleman's been in the job. Is this a recent problem? Has anything changed in the workplace or in him? Also, I'm guessing the job demands bright light to help with spotting defects. That said, the light shouldn't need to be directed anywhere other than at the thing being checked. Is it reflected back off the thing being checked?