| 摘要 |
With present methods, it is difficult to determine whether an e.g. pneumo-peritoneum needle has penetrated too far, thereby injuring an internal organ, or not far enough. This invention uses reflected light to trigger a visual or audible signal. A light source (8) faces one end of an optical fibre (5) inside the needle the far end of which coincides with the tip (X) of the needle. Another optical fibre (6), lying alongside the first, returns reflected light to a phototransistor (10) which faces its near end and which is screened (9) from the light source. The output of this phototransistor drives a l.e.d. which serves as a visual indicator. Alternatively, this output is further processed in an electronic circuit including a comparator to drive, in addition to the l.e.d., a loudspeaker producing an audible alarm signal, depending on the intensity of the reflected light. |
