| 摘要 |
The trifocal mirror reflector uses mirrors with elliptical cross sections and provides a common complementary focus (f1) which acts as the centre of rotation of the rays from focal lines (f1-f2 and f1-f3 and f2-f3), in either horizontal or vertical planes. The reflector is used in lamps which have light sources placed at one or several foci. The reflector system provides a common complementary focus (f1) which is the centre of rotation of the focal line (f2-f3) about the axis (f1) perpendicular to the line (f2-f3), or the centre of rotation of focal lines (f1-f2) and (f1-f3) about the axis (f1) perpendicular the line (f2-f3), (f1-f2) being equal in distance to (f1-f3). In this case, an annular light source e.g. a fluorescent tube, may be placed along the annular focal line (f2-f3) giving a narrow circular aperture about the focus (f1). |
