| 摘要 |
<p>1468566 Measuring distance photo-electrically ALCYON ELECTRONIQUE & PHYSIQUE SA 28 Aug 1974 [31 Aug 1973] 37562/74 Heading G1A Apparatus for measuring a tunnel section comprises: means arranged to illuminate a spot on the tunnel wall; optical means for imaging the spot; and analyzing means responsive to the image for providing an indication of the distance of the spot from the tunnel axis, the analyzing means including a rotatable disc on which the spot is imaged and having a spiral slit and a series of radial slits at equal angular increments. A He-Ne laser 1 Fig. 1 radiating about 1 mW projects a beam 2 perpendicular to a tunnel axis 3 to illuminate a spot 4a on the tunnel wall 5, distant R from the axis 3. An interference filter 10 admits reflected light to an optical system 7 coaxial with the tunnel and distant p from the transverse plane containing the point 4a. The optical system 7 focuses an image of the spot 8 at a radius R' on a motor-driven disc 9 coaxial with the tunnel and distant p' behind the optical system 7, the radius R' thus being a constant fraction of R. The analyzer disc 9 Fig. 2 has a spiral slit 11 tracing a path of radius uniformly variable with respect to angular displacement from a reference slit 12. Uniformly spaced radial slits 13 provide calibration marks representing units of the measured distance R. A display counter or recorder 20, gated on by a photo-cell 18 sensing the reference slit 12, counts pulses from the photo-cell 16 in response to calibration slits 13, until gated off by a photomultiplier 19 which senses when the slit 11 is coincident with the image at 8. A plurality of lasers 1 shining in various transverse directions, co-operating with a plurality of elements 15-19 placed at respective corresponding positions behind a disc 9, may be mounted on a railway bogie, Fig. 4, (not shown) so as to plot points around a transverse section. As the bogie travels, any one group of elements may be used to trace out a record of a corresponding longitudinal section. Means may be provided for comparing measured distances R with a master gauge, and for indicating, or recording, or sounding an alarm, whenever R deviates from the master gauge by more than a predetermined amount.</p> |
