| 摘要 |
<p>A catheter assembly (20) for measuring a fluid pressure in a body cavity includes pulse modulator (39) responsive to an electrical power source (33) for energizing a light-emitting diode (45) which has drift characteristics which vary in response to temperature. An optical sensor (22) is adapted to receive the light from the light-emitting diode (45) and to provide a measurement signal indicative of the fluid pressure in the cavity. This measurement signal has undesirable characteristics related to the thermal drift characteristics of the diode. A detection circuit (58, 60) detects the measurement signal and provides an output signal indicative of fluid pressure in the cavity. A special filter (63) is included in this detection circuit which has optical characteristics that substantially offset the undesirable characteristics of the measurement signal, so that the output signal is substantially independent of the temperature of the diode. A power conversion circuit (36) enables the assembly to be energized by an excitation voltage which is provided in several different forms by various monitors.</p> |
