Video System and Laser Incompatibility

 In the Biomedical work place we are often confronted with compatibility problems with different manufacturers' equipment. The following situation caused some confusion at my facility and could possibly occur at yours.

 My hospital had recently purchased new Storz video equipment for GYN Laserscopy (Storz Telecam Video System model# 20210120). The camera is a single chip and supplies a much better image than our old systems. Soon after the new systems had been put into service, we received a complaint from the O.R. that the screen was "strobing" like a disco lounge when used in conjunction with our Laserscope KTP Laser. Initially the complaint was not confirmed, since when the video systems and laser were op tested, the problem could not be duplicated.

 A week or so later the strobing reoccurred. At this time a more thorough examination of the situation was was performed and the following is what was discovered: I set up the video system as it would be for a surgical case. My facility uses the "Eye Safety Filter" on the laser (an electromechanical device between the laperoscope and the camera head), as opposed to a permanent filter. After threading the laser fiber through the scope and looking at the aiming beam with the naked eye, it looked normal. However if you looked at the aiming beam on the video monitor, it was strobing. I tried the permanent filters to clean up the aiming beam, but they filtered it out completely.

 The video systems were picking up the pulsing from the laser's aiming beam. It is important to note that the Laserscope Water Cooled KTP (model# 703) has an aiming beam that stays on constantly, the problem that we were experiencing only occurred on the Air Cooled Laserscope KTP (model # 803). The Laserscope Service Tech explained that the Air Cooled KTP pulses its aiming beam at a rate of about 84 Hz, in order to conserve power and reduce heat. We confirmed that the Storz video camera scans at a rate fast enough to see the aiming beam turn on and off. At this point in time we had two companies that said it was the other guy's problem. After discussing the situation with each companies' sales and service departments it was decided that the best fix was to upgrade the laser with a constant aiming beam.