JPH0130132B2 - - 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. Provided, the focusing plate 2
When focusing is performed with the imaging lens 1 while observing the visual field of 3 As shown in Figure b, cylindrical lens 3
The image portion 5 ₂ visible on the _screen and _the image portions 5 ₁ , 5 ₃ visible on the reticle surface above and _below it appear to coincide with a single 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 parts of the board surface 5 ₁ , 5 ₃
It looks out of place. In this case of defocusing, the feature of this type of rangefinder is that the image portion ₅₂ visible to the cylindrical lens 3 appears to rotate due to the increase or decrease in the amount h of off-axis.

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 cylindrical lenses are used: (a) each cylindrical lens is placed apart, and (b) each cylindrical lens is placed adjacently 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, in (a), the image of each cylindrical lens part is simply compared with the image of the focus plate surface around that lens, so it is similar to the one 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 shadows will appear 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 focusing plate in which a plurality of distance-measuring cylindrical lenses are arranged adjacent to each other with different generatrix directions, and the in-focus or out-of-focus of the optical system can be determined from the coincidence or misalignment of the visual field images on both sides of the boundary between the adjacent cylindrical lenses. The gist is:

FIG. 4 shows a first embodiment of the present invention, in which three cylindrical lenses 3 ₁ , 3 having the same radius of curvature r are shown.
₂ , 3 ₃ and connect them to concentric boundaries 6 ₁ ,
6 ₂ adjacent to each other, and each lens 3 ₁ , 3 ₂ ,
A rangefinder is constructed by shifting the generatrix directions 3' ₁ , 3' ₂ , and 3' 3 of 3' ₃ by 90 degrees from each other, and the distance meter is placed at the center _of the focal plane of the reticle and the generatrix direction is set at an angle of 45 degrees to the horizontal plane. Install it in a tilted position. Figures 4b and 4c are respectively
FIG. 3 is a sectional view taken along line bb and line cc in FIG.

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 be matched in series is the concentric circle 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

Figure 7 also shows three cylindrical lenses 3 ₁ , 3 ₂ , 3
This shows a second embodiment in which they are arranged adjacent to each other in the top, middle and bottom with straight boundary lines 6 ₁ and 6 ₂ , and the generatrix direction 3' ₂ of the middle lens 3 ₂ is used _. The upper and lower lenses 3 ₁ and 3 ₃ are aligned in the generatrix direction 3'
₁ and 3' ₃ are arranged at right angles. Also, those 3
The cylindrical lenses 3 ₁ , 3 ₂ , and 3 ₃ have the same radius of curvature r, and the centers of curvature A ₁ , A ₂ , and A ₃ pass directly below point G. FIGS. 7b, c, and d show side views of each lens 3 ₁ , 3 ₂ , and 3 ₃ in the direction of the leader line in FIG. 7 a.

Therefore, the distance measurement accuracy increases from the cylindrical lens 3 ₃ to 3 ₂ and 3 ₁ . Figure 8 shows the appearance of the focusing plate in the example in Figure 7 above when it is out of focus, and the vertical line of the image 5 seen by each lens goes from lens 3 ₃ → 3 ₂ → 3 ₁ toward the top, the larger the deviation becomes. Not only does it appear to rotate, but the horizontal line of the image 5 also rotates. 9th
The figure shows the shadow 7 that occurs when a lens with a dark F number is used as the imaging lens 1. Even if such a shadow 7 occurs, there is no shadow at the boundary line 6 ₂ between the lenses 3 ₃ and 3 ₂ . Distance measurement with sufficient accuracy can be easily performed with image shift in the area.

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, distance measurement can be performed by sharply separating images, and this is an effective and suitable improvement for this type of reticle.

[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 the first embodiment of the present invention, Figure a is a plan view, Figures b and c are line bb and c- Fig. 5 shows the view of the rangefinder shown in Fig. 4 when it is out of focus, Fig. 6 shows a state in which shading occurs, Fig. 7 shows the second embodiment, and Fig. Plan view, b, c, and d of the same figure are side views of each cylindrical lens in the direction of the lead line in figure a, Fig. 8 is the view when the rangefinder in Fig. 7 is out of focus, and Fig. 9 is a state with overshadowing. figure. 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, and 6 ₁ and 6 ₂ are boundary lines.

Claims (1)

[Claims] 1. In a focusing plate in which cylindrical lenses are arranged so that the generatrix of the lens is parallel to the focal plane, a plurality of cylindrical lenses are divided into sections where the generatrix intersects each other and the parts of each cylindrical lens are adjacent to each other alternately. The visual field images on both sides of the boundary between adjacent cylindrical lenses match and
A focus plate characterized by being able to determine whether an optical system is in focus or out of focus based on the deviation.