JPH0130133B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a focusing plate with a rangefinder for optical equipment, and in particular, it is called Duo Focus, in which a cylindrical lens is provided as a rangefinder on the surface of the focusing plate, and one of the cylindrical lenses is provided with a cylindrical lens as a rangefinder. The present invention relates to an improvement in a focus plate that performs distance measurement (focusing, distance adjustment) using directional image magnification or reduction power.

First, the principle of distance measurement using a cylindrical lens will be explained with reference to FIGS.

In Fig. 1, 1 is an imaging lens of an optical device, 2 is a focusing plate disposed on the focal plane of the optical device, and a cylindrical lens 3 serving as a rangefinder is located at the center of the focal plane of the focusing plate 2. It is provided with the generatrix parallel to the surface. For distance measurement, focusing of the imaging lens 1 is performed while observing the cylindrical lens 3 from the rear 4 of the focusing plate 2.

In Fig. 2, O-O is the optical axis of the cylindrical lens 3,
Let r be the radius of curvature of the cylindrical lens centered on point A, and f be the focal length of the cylindrical lens 3. When the lens 3 is a thin type, the focal length f is f=r/n-1 (n=refractive index of the cylindrical lens 3).

Now, suppose that the light L from the imaging lens 1 (Fig. 1) is incident on a point B of the cylindrical lens part that is a distance h away from the optical axis O-O of the cylindrical lens 3, then the incident light L
When the light exits the cylindrical lens 3, it deflects at an angle δ and heads toward the cylindrical lens focal point C. The deflection angle is δ=h/f
is proportional to the off-axis amount h of the incident light.

When the main surface of the cylindrical lens 3 is a finer focal plane, the image formed by the imaging lens 1 is shifted by dx from the main surface of the cylindrical lens 3 toward the rear focal point side or the front focal side of the cylindrical lens. When the imaged state (out-of-focus state) is viewed through the cylindrical lens 3, the image appears to be deflected in a direction perpendicular to the optical axis O--O of the cylindrical lens due to the prism effect of the lens 3. The amount of deflection dh is dh=δdx=h/fdx, which is proportional to the amount of axis deviation h of the imaging point from the optical axis O-O of the cylindrical lens and the amount of defocus dx, and the focal length f of the cylindrical lens 3.
is inversely proportional to.

That is, in the case of the rear focus state, point B appears to be at point D, and h is observed to be reduced to _h1 . Also, in the case of the front focus state, point B appears to be point E, and conversely, h is enlarged and observed as h ₂ . In other words, the cylindrical lens 3 has a function of reducing or enlarging the off-axis amount h of the defocused image. This function works only in the direction perpendicular to the cylindrical axis of the cylindrical lens 3, and does not work in the axial direction.

Therefore, such a cylindrical lens 3 is placed at the center of the focal plane of the focusing plate 2, with the cylindrical lens generatrix parallel to the focal plane of the focusing plate, and the generating line direction is tilted, for example, by 45 degrees with respect to the horizontal line, as shown in the third figure. When the imaging lens 1 is focused while observing the field of view of the focusing plate 2, the image 5 of the object to be measured (for convenience, it is assumed to be a single vertical line image) is visible through the imaging lens 1. When in focus, as shown in FIG. 3b, the image portion 5 ₂ visible to the cylindrical lens 3 and the image portions 5 ₁ , 5 ₃ visible to the focusing plate surface above and below it are composed of three parts 5 ₁ , 5 ₂ , 5 . ₃ It looks like it fits the line. On the other hand, when the front focus or the rear focus is out of focus, the image portion ₅₂ visible to the cylindrical lens 3 is tilted and brought into focus as shown in Figure 3 a (front focus) or Figure 3 c (rear focus). Upper and lower image portions of the board surface 5 ₁ , 5
It looks out of place compared to ₃ . In this case of defocus,
The image portion 5 ₂ visible to the cylindrical lens 3 has the above-mentioned off-axis amount h
A feature of this rangefinder is that it appears to rotate in proportion to the increase or decrease in the distance.

Note that the above phenomenon occurs even if a concave cylindrical lens is used instead of a convex cylindrical lens 3, and in this case, the direction of image enlargement/reduction due to focal shift is opposite to that when using a convex cylindrical lens. Become a relationship.

Therefore, the optical equipment is adjusted so that the visual field image 5 of the focusing plate 2 appears to be such that the cylindrical lens portion 5 ₂ and the focusing plate surface portions 5 ₁ and 5 ₃ above and below the cylindrical lens portion are aligned in a line, as shown in FIG. 3b. Distance measurement is achieved by performing focusing. The above is the general principle of distance measurement.

An actual reticle is constructed by providing one or more cylindrical lenses 3 on the focal plane of the reticle. Two or more lenses are used: (a) each cylindrical lens is placed apart, and (b) each cylindrical lens is placed adjacent to each other in parallel so that the direction of the boundary line is the same as the generatrix direction of the cylindrical lens. Two types of arrays are currently known.

However, method (a) simply compares the image of each cylindrical lens section with the image of the focus plate surface around that lens, so it is similar to the method using only one cylindrical lens. has the disadvantage of low ranging accuracy.

In addition, (b) has better distance measurement accuracy than (a), but if the imaging lens 1 of the optical device has a dark F number, black shading will occur at the boundaries of each cylindrical lens, making measurement at the boundaries difficult. This method has the disadvantage that it becomes difficult to determine the distance, which reduces the accuracy of distance measurement.

The present invention similarly configures a rangefinder by arranging a plurality of cylindrical lenses adjacent to each other, but it can be easily and accurately maintained no matter what F number lens is used as the imaging lens 1 of the optical device. The object of the present invention is to provide a focusing plate with a rangefinder of this type capable of distance measurement, which includes a cylindrical lens for distance measurement on the focal plane with its generatrix parallel to the focal plane. A convex type and a concave type cylindrical lens for distance measurement are placed adjacent to each other with their generatrix directions parallel to each other, so that it is possible to know whether the optical system is in focus or out of focus from the coincidence or deviation of the visual field images on both sides of the boundary between adjacent cylindrical lenses. The main focus is on the focusing plate.

FIG. 4 shows an example, in which three cylindrical lenses 3 ₁ , 3 ₂ , _{3 3} of convex, concave, and convex shapes are arranged in order from the center.
The cylindrical lenses are arranged adjacent to each other with concentric boundary lines 6 ₁ and 6 ₂ , and the radius of curvature r of each cylindrical lens is the same, and the generatrix directions XX are parallel to each other. Cylindrical lenses 3 ₁ , 3 ₂ , and 3 ₃ are formed on the focal plane of the focal plate with the generatrix direction XX inclined at 45 degrees with respect to the outer periphery of the focal plate. Figure 4b is Y in Figure 4a.
-Y line (perpendicular direction to generatrix XX) sectional view.

FIG. 5 shows the appearance of the focusing plate in the example shown in FIG. 4 when out of focus _.
3 ₂ and 3 ₃ show enlargement and reduction in mutually different 45° directions, so the images in each lens appear to rotate in opposite directions. That is, the vertical line of the image 5 that should match linearly is the concentric boundary 6 of each lens 3 ₁ , 3 ₂ , 3 ₃
The images are separated to the left and right inside and outside of ₁ and 6 ₂ , like a split image rangefinder. Therefore, compared to the conventional cylindrical lens alone as shown in Figure 3, the distance measurement accuracy is 2.
twice as much. In addition, this example uses three types of cylindrical lenses 3 ₁ , 3 ₂ ,
Since it was configured with 3 ₃ attached, the boundary between the two 6
₁ and ₆₂ have two different ranging accuracies. Therefore, the imaging lens 1 of the optical device is set to a bright F
If it is a F-number, the image deviation at the outer boundary ₆₂ is used for distance measurement, and if it is a dark F-number, the image deviation at the inner boundary ₆₁ is used for distance measurement. Dark F
For the number, cover 7 as indicated by the diagonal lines in Figure 6.
It is possible to always measure distances with high accuracy even when

As described above, according to the present invention, in a focusing plate that uses a cylindrical lens as a rangefinder, it is possible to not only easily and accurately measure distances no matter what F-number imaging lens 1 is used, but also to Even if the distance object is not only a vertical line but also a horizontal line, it becomes possible to measure the distance by making a sharp separated image, and this is an effective and appropriate improvement for this type of reticle.

In the illustrated embodiment, adjacent concave and convex cylindrical lenses are arranged with concentric boundaries 6 ₁ and 6 ₂ , but the concave and convex lenses may be arranged with straight boundary lines.

[Brief explanation of drawings]

Figures 1 and 2 are diagrams explaining the principle of distance measurement using a rangefinder that uses a cylindrical lens, and Figure 3 shows the view of the focus plate field. , Figure c shows the rear pin state, Figure 4 shows an embodiment of the present invention, Figure a is a plan view, Figure b
5 is a sectional view taken along the Y--Y line in FIG. 1 is an imaging lens, 2 is a focusing plate, 3, 3 ₁ , 3 ₂ ,
3 ₃ is a cylindrical lens, 5 is a visual field image, 6 ₁ and 6 ₂ are boundary lines, and 7 is a shadow.

Claims (1)

[Claims] 1. In a focusing plate in which a cylindrical lens is installed so that the generatrix of the lens is parallel to the focal plane, the convex and concave cylindrical lenses are aligned in the generatrix direction, and the parts of each cylindrical lens alternately form annular sections. 1. A focusing plate, characterized in that the focusing plate is arranged so as to form a cylindrical lens, and the focusing/out-of-focusing of an optical system can be determined from the matching/misalignment of visual field images on both sides of the boundary between adjacent sections of a cylindrical lens.