| 摘要 |
A device for locating a vein (31, fig. 3) in a subject (21, fig. 2), the device comprises: a source of collimated or focussed radiation 103 to radiate a point 117 on the subject; and a detector 105 for detecting the radiation scattered from the point, and its surrounding area. An indicating means e.g. a display 192 indicates the size of the detected radiation signal relative to the size of the detected radiation collected from the other points on the subject. The source may be monochromatic, or it may emit wavelength in the range of 400 to 450 nm; 535 to 550 nm; 575 to 585 nm or 700nm upwards. A shield 190 which is made of material opaque to the radiation and has a window 191 may be provided over the detectors 105 to stop stray radiations, and to allow only scattered radiation reaching the detectors. A marking means 113 may be provided to mark the position of a vein derived from the detected radiation. A gain control 196, and suppression control 194 may be used to configure a calibration measurement for the display, and to amplify its full scale deflection. |
