PURPOSE: To enhance the reliability of a measuring instrument for the separation of a trolley wire by performing a spectrum analysis, selectively using an effective and suitable optical filter and employing a comparison system with a background light instead of an electric filter, thereby remarkably improving an S/N ratio.
CONSTITUTION: Since the spectra S1, S2 of an arc light are constant in the wavelength, a band filter is used as an optical fiber for the arc light only for an object of the S1 having larger intensity. Thus, the S/N ratio can be improved. Then, a photodetecting system is composed of a photodetecting lens 18a corresponding to the arc light 8, thereby obtaining a detection signal for the sum of the arc light and the natural light (background light) of the background shown in Fig. a. A detection signal for the background light shown in Fig. b is obtained by a photodetecting lens 18b corresponding to the background light except the arc light. Since both the background lights can be regarded as being the same by suitably setting the visual fields of the lenses 18a, 18b, a detection signal having high reliability for the arc light shown in Fig. c can be obtained by using the difference of both by the differential calculator 23.
ICHIKAWA MATSUTAROU
NAKAMA FUMIO
TAKENAKA YASUO
ABE SHINJI
TAKAHASHI KENSAKU
HITACHI LTD
HITACHI ELECTR ENG
| JPS5396881A | 1978-08-24 | |||
| JPS536065A | 1978-01-20 |