Compound-cavity tactile sensor using surface-emitting laser [for endoscope/catheter tips]

A tactile sensor which has an optical compound-cavity interferometer using a surface-emitting laser (SEL) is fabricated. An interferometer with a SEL does not need optical components such as lenses and beam-splitters. Thus this sensor is simple and suitable for miniaturization. A SEL, a photodetector (PD) and an external cantilever mirror are all integrated in one chip with hybrid technology. The total size is 1.4×1.8×0.65 mm³. When a force is applied to the cantilever mirror and an external cavity length is changed, the optical power is strongly modulated with a λ/2 period, which is induced by the phase shift of the feedback beam from the external mirror. The sensitivity of approximately 1 mN/p-p is obtained, and this result shows the possibility of miniaturization and high sensitivity of the tactile sensor