JPH0130134B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reticle, and particularly to a reticle having a split prism in the center.

A focusing plate having a split prism in the center is known, in which the center portion is divided into two parts, and the upper and lower wedge directions are opposite to each other. In this reticle, whether or not the focus is in focus is determined by observing the split state at the boundary line between the prism pairs.

An object of the present invention is to provide a focusing plate that makes it easier to determine focus by adding another splitting portion to the focusing plate.

The reticle of the present invention is characterized in that a pair of thin annular prisms having a wedge direction different from that of the main prism is inserted into the distance measurement area consisting of the split prism in the central portion.

Next, embodiments of the present invention will be described with reference to the drawings.

In FIG. 1, reference numeral 1 indicates a focus plate, and reference numeral 2 indicates a central distance measurement area. This central part has a boundary line that is inclined at 45 degrees with respect to the horizontal line, and the wedge direction is parallel to the boundary line. It has a shape in which a pair of thin annular prisms are inserted, each consisting of prisms 5 and 6 having a boundary line in a perpendicular direction and a wedge direction perpendicular to the main prism. In this distance measuring section, when 5 and 6 are not present, 3 and 7 form one continuous prism. The same applies to 4 and 8. In FIG. 1, the arrow inside the prism indicates the wedge direction, and the cross sections along the - and - lines are as shown in FIGS. 2 and 3, respectively.

The boundary line of a split prism divided into two parts is often parallel to the left and right direction, but since there is no split effect at all for objects that extend in the left and right direction, the boundary line is tilted at 45 degrees to the left and right, and the boundary line is parallel to the left and right directions. Some devices have the ability to measure distances even for objects that extend in the same direction. Although this allows focusing on objects extending both vertically and horizontally, the images are separated diagonally, making it visually difficult to focus. When using the focusing plate of the above embodiment,
As shown in Figure 4A, when object a is observed, it appears as shown in Aa when the object is out of focus, and in addition to the object extending vertically and horizontally being split diagonally, it also appears almost vertically or horizontally. A horizontally split portion is added, making focusing easier than with conventional focusing plates. Moreover, since the inserted pair of annular prisms is thin, when the image is out of focus, the image is visually defective and the out-of-focus is visually emphasized.

FIG. 4B shows another embodiment, in which the boundary line of the thin annular prism pair coincides with the main prism pair, and the wedge direction is opposite to the main prism pair. In this embodiment, it is not possible to focus on an object extending in the horizontal direction, but for objects extending in the vertical direction, it has a higher distance measuring ability than the first embodiment, makes the defective state of the image more noticeable, and focuses on the object extending in the vertical direction. Makes alignment easier. Ba shows the appearance of object a when observed through this focus plate.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the focusing plate of the present invention;
2 and 3 are sectional views taken along lines - and - in FIG. 1, and FIG. 4 is a diagram showing the wedge direction of the embodiment and the appearance when the object shape is out of focus. In the figure, 1 is the focusing plate, 2 is the central part, 3, 4, 5,
6, 7, and 8 are divided portions, and the arrow in FIG. 4 indicates the wedge direction.

Claims (1)

[Claims] 1. In a reticle that has a split prism in the center, which is composed of optical wedges whose inclination directions are opposite to each other, a narrow annular prism having an inclination direction different from that of the pair of optical wedges and which is sandwiched in concentric circles. 1. A focusing plate characterized in that a pair of molded optical wedges are superimposed so that the centers of the concentric circles are located on the boundary line of both optical wedges of the split prism.