| 摘要 |
PURPOSE:To efficiently utilize a luminous flux of a detection object obtained from an objective lens, and also, to secure the degree of freedom of a design by constituting the title lens so that a difference of effective ranges of first and second lens pieces and third and fourth lens pieces. CONSTITUTION:Convex faces of the first and second lens pieces 20a, 20b are constituted so as to become the same curved face shape, and also, so as to come into contact with each other by a mutual curved face-shaped shared borderline CAB. Also, convex faces of the third and fourth lens pieces 20c, 20d are constituted so as to become the same curved face shape, and also, so as to come into contact with convex faces of the first and second lens pieces 20a, 20b by shared borderlines CAC, CBC and CAD, CBD, respectively. Accordingly, a difference of effective ranges of the first and second lens pieces 20a, 20b, and the third and fourth lens pieces 20c, 20d can be set arbitrarily. In such a way, a luminous flux of a detection object obtained from an objective lens can be utilized efficiently, and also, the degree of freedom of a design can be secured. |
