FR2615633A1 - VIEWER FOR STEREOSCOPIC PAIR OF VIEWS - Google Patents

Abstract

VIEWER 10 FOR A STEREOSCOPIC PAIR OF PHOTOGRAPHIC VIEWS 22. PAIR 22 IS LOCATED LESS THAN THE FOCAL DISTANCE BEHIND A PAIR OF 12, 14 FRESNEL LENSES, THE WIDTH AND HEIGHT OF WHICH ARE AT LEAST EQUAL TO THOSE OF THE VIEWS 22 OF THE STEREOSCOPIC PAIR. THE SPACING, IN THE WIDTH SENSE, BETWEEN THE OPTICAL AXES AND THE LENSES IS SUCH AS THE RADIUS, FROM THE LEFT IMAGE AND THE RIGHT IMAGE AND EMERGING FROM THE LENSES AT JUNCTION 15 OF THESE LENSES, ARE SENSITIVELY PARALLEL. PRESBY OR MYOPIC PEOPLE CAN SEE THE IMAGES IN FOCUS BY HOLDING THE VIEWER A CORRECT DISTANCE FROM THE EYES. APPLICATION: STEREOSCOPIC AND THREE-DIMENSIONAL VIEWS.

Description

This invention relates to the viewing of stereoscopic views and,

  in one of its aspects, it relates to an improved stereoscopic viewer for

  allow users to view pairs of

reoscopic views.

  It is well known that if you take two pictures

  phies under slightly different angles, then that a person sees them correctly, and separately from the left eye and the right eye, she gets a view

  unique combination with a three-dimensional depth effect

  nelle. Such pairs of photographs are known

  under the name of stereoscopic pairs.

  There have been many proposals for

  photographic reils able to take a pair of

  stereoscopic views and for vision viewers

  the pair of stereoscopic views that result.

  A widespread viewer has two small

  magnifying glasses acting as eyepieces, and one goes up to the correct distance of the lenses, a pair of views

  stereoscopic images and we view them through the lenses

  the. In practice, it looks very much like watching

  in a pair of binoculars and has the same drawbacks

  nients: 1) To see the whole picture, you have to put your eyes very close to the eyepieces. Users who wear glasses will sometimes find this difficult

  to do especially since it is known that glasses made from

  plastic glasses may be scratched by rubbing

  against the frames of the eyepieces.

  2) Nobody has a perfect vision and

  Even glasses can not correct them completely.

  defects. To read comfortably, a person

  myopic sound will tend to hold the document closer

  of his eyes and, conversely, for a presbyopic person.

  With a conventional stereo viewer, it is not possible to hold the camera closer or further

  eyes. Everyone must put it right against the eyes.

  To overcome this problem, the best viewers

  have a focusing device, which moves the

  along the lens axis and actually move the virtual images closer to or farther from the eyes. 3) The range of our eyes also varies between about 55 mm and 70 mm> and the best binoculars and the best stereo viewers also have a spacing adjustment, so that the optical axes of the eyepieces can be adjusted to coincide with those eyes. Some people are not competent

  to properly set these eyepieces.

  4) The eyes are able to compensate for weak

  eyepiece adjustment errors, however, this

  as eye fatigue and sometimes results in headaches, so some people do not like to look through similar devices

to binoculars.

  An object of the invention is therefore to propose a vision

  for stereoscopic pairs of views, in the-

  what these disadvantages are overcome or reduced.

  According to the invention, the viewer comprises a pair of lenses through which the user views a pair of stereoscopic views, a means for holding a pair of stereoscopic views behind the lenses so that the distance between the lenses and the

  pair of stereoscopic views is less than the dis-

  focal length of the lenses, so that one can see

  magnified virtual image; each lens having dimensions

  in width and height, at least as large as

  that the corresponding dimensions, in width and in

  each view of the pair of stereoscopic views,

  so that users can go

  presbyopia to myopic people, each person holding the correct remote viewer of the eyes this way that the focus of the images allows that person to see the entire image, the spacing, in the sense of the width between the optical axes of the lenses being such that the rays coming from the image

  on the left and the image on the right and emerging from

  at the point between the two lenses are substantially parallel so that it is not necessary for the user's eyes to diverge in the direction of the lenses and so that the lenses give the equivalent of the optical prisms for bending the images, which the user sees in a scene that diverges outwards, in one direction, ahead of the lenses, which is an extension of the direction

  defined by the pair of stereoscopic views and the

  daughters. So I found that by using this provision,

  you can avoid having to make a mechanical adjustment

  tif of the focal distance as well as the spacing of the lenses in the width direction and that this simplifies

  obviously a lot of the construction of the viewer.

  It is sufficient for the user to hold the viewer at a distance from his eyes that suits his own conditions,

  in order to obtain the focus of the images, and the ef-

  desired three-dimensional fetus is obtained. In addition,

  will have an aperture large enough for all users to see fully

the stereoscopic pair.

  Since the lenses are quite large, it is desirable to use Fresnel lenses

  to reduce clutter and weight.

  The pair of stereoscopic views will normally be a pair of photographic views or prints obtained (s)

  photographing a scene with a photographic camera

  stereo sound. That's why the viewer features

  a way to mount the pair of views-.

  In a simple embodiment of the invention, the

  The cameras are provided with a means for finding the focus distance. Just then the user

  hold the lenses in front of the pair of stereoscopic views.

  The invention will now be illustrated with reference to the accompanying drawings, in which: FIG. 1 is a perspective view of an exemplary viewer according to the invention; Figures 2 to 7 are diagrams showing the viewer design;

  Figures 8 to 10 are diagrams showing the con-

  a modified system, which includes a focus distance search means; and Fig. 11 is a diagram of the resulting lens system.

  Referring to the drawings, we see that the vision

  10 has a front face 11, in which are

  supported a pair of Fresnel lenses 12 and 14.

  These lenses are in contact along a vertical line 15. At the rear is provided a vertical support 20 for

  a pair of stereoscopic views 22, which are a

  single image with two distinct views placed vertically

  parallel to the lenses 12 and 14. The views 22 are held vertically against the support

  by a pair of arms 24 which are at a certain distance

  forward and have slits 25 in which

  they come to lodge the edges of views 22.

  The front face and the rear support are maintained at a distance from one another by a base 26

trapezoidal shape.

  To study the viewer 10, it is necessary to determine the distance U between the pair of stereoscopic views 22 and the lenses 14 and 16. This is obtained using the well-known formula:

I1 1 1

_ + _ = -

U V F

  where U is the distance between the lenses and the stereoscopic pair, V is the distance between the resulting image and the lenses and

  F is the focal length of the lenses.

  If we choose that the image will be, say, 500 mm

  In order to be certain that U is less than F, and if lenses of focal length of, say, 190 mm are chosen, then the above formula gives U equal to 138 mm.

  The resulting viewer 10 is shown schematically

  In a side view in Figure 2. As can be seen, the virtual image is behind the object, that is behind the stereoscopic pair.

  is enlarged relative to each image of the pair.

  To now determine the relationship between lens size, image size, and

  distance of vision, one must take into account the gross-

  and, referring for example to page 140 of Francis Weston Sears' "Optics" book: Magnification = 2. if the user views from F 250 mm ahead of the stereoscopic pair ie

  112 mm in front of the lenses. In this case, therefore,

  if the height h of the photographic view is 90 mm, then the apparent enlarged dimension of this view will be 250 mm

  x 250 mm (F being 190 mm), that is to say 118 mm.

  In the case of the viewer 10 and referring to FIG. 3, it was assumed that the distance between the virtual image and the lenses was 500 mm and it can then be mathematically determined by the reports that the effective dimension of the virtual image is 289 mm, that is to say

500 + 112

  dimension of the image = 118 x 500 112 = 289 mm

  Again, and referring to Figure 4, using

  the relationship of similar triangles, if the height H of the lenses is 130 mm, and if the size of our

  viewer's lenses is 130 mm, so the eyes can

  be at a distance of X mm and still see the entire image. We can calculate X as follows:

X + 500 X

289,130

  which allows to deduce that X = 408 mm.

  In other words, you can hold the viewer right against the eyes or at a distance of up to 408 mm and the eyes can still see the entire image. Lenses 12 and 14 should be cut into a rectangular shape of the same size, that is to say, of the same proportion between height and height as the stereoscopic pair of views, and should be mounted exactly one against the other. another without play between the two lenses. It should also be noted that while dimensions, in

  width and height, lenses are equal to

  mounts stereoscopic views, or greater than these dimensions, then it is possible to see the totality

  of the image at any distance to infinity.

  We will now examine the effect of eye-to-eye on the viewer structure. It is indeed necessary to present the two images to the brain as if these light rays came from a single three-dimensional source. Referring to Figure 5, assuming that the step of the pair of stereoscopic views, i.e.

  spacing, in the width direction, of identical points

  ticks located in the center of the two views, is 65 mm, and that it is desired that the rays emerge from the lenses parallel in the region of the Junction between the two lenses, then: tg8 = 325 + 0.236

and e = 13.33 '.

  Assuming that the refractive index of the sine lenses is 1.5, then, according to Snell's law, we have S-n8- 1.5 sina oaa is the angle of the emergent ray with the normal and e

  is the angle of the incident ray with the normal. We also

  lament 6 = - -a = 13.3 '. Using an infre-

  simple mathematic and by measuring the value of a in steps of 1 ', we can see that an angle a - 24' will satisfy this condition, that is to say that the half-angle of aperture or angle of the prism equivalent, of each lens on the edges where they come against each other must

Be 24 '.

  It can be seen that a lens will act as a prism if it is used outside its optical axis. By

  Therefore, since the lenses 12 and 14 of the vision-

  10 must give the effect of an angle prism equal to 24 ', and since it is also known, from the

  page 91 of the book "Optics", to which reference was made here

  above, only for a thin refractive index lens

  1.5, the radius of curvature is equal to half the focal length, the approximate radius of curvature - lenses 12 and 14 is

190

  190 = 95 mm Referring to FIG. 6, 'if x is the distance

  between the center of the curved face and the edge of the lenses

  the, Sin 24 = - x so x = 38.6 mm Therefore, the two lenses 12 and 14, side by side, must have their centers arranged at 38.6 mm x 2 from each other, ie, in other words,

at 77.2 mm from each other.

  With this arrangement, the result is that shown in Fig. 7. When viewed from any point in region 40, the enlarged virtual images of the separate objects 22 will always appear as a single image and the pair of lenses 12, 14 will seem to act as a single continuous lens. There is no risk of double vision and an observer placed at a great distance (say I meter) will always see the

  the entire image of the stereoscopic view of which the

  is formed by the left view and the other half by the right view. This therefore has the advantage of providing an image "catching the eye" that can be useful

  for publicity purposes and, when the observer is

  prochera, he will see again the three-dimensional effect assured

by the viewer 10.

  In the situation shown in FIG. 7, it should be noted that at the junction between the two lenses, the image on the left and the image on the right will appear

  in the form of parallel rays. The other diverse rays

  progressively, and it is not necessary that the

  the user's eyes diverge to look directly at

  lentils. In addition, provided that the space

  width, between the optimum axes of

  If the lenses are larger than the minimum normal spacing between a person's eyes, no eye will need to diverge to view the viewer 10. If in this example the spacing is 77.2 mm, is therefore greater than the typical minimum clearance of the eyes

which is 70 mm.

  So this is a feature of the viewer

  form to. the invention that no undesirable mono-image will normally be seen on either side of the stereo image if viewed inside a cone based on the junction between the lenses and presenting An angle 0, as above, as is often the case with conventional viewers. Therefore, it is not necessary to provide a mask, which greatly simplifies the construction of the viewer and, moreover, it makes it easy to fold the lenses 12 and 14 and the rear support 20 flat with the base

  26 when the viewer is not used.

  In a modified embodiment, it is sufficient to have the lenses 12 and 14, but then it is useful to have a focus distance finder device 50, which can be useful to the user to determine that he is holding. the pair of stereoscopic views 22 approximately at the correct distance of the lenses 12 and 14. Figure 11 shows such an arrangement. The focusing distance search device 50 can be placed under the lenses 12 and 14 and, as will be explained,

  can be formed by a portion of the Fresnel lenses.

  In fact, these lenses and lenses 12 and 14 can

  all be obtained as a single piece in terms of

molded plastic.

  We will now explain the procedure of the dis-

  50 positive search of focus distance.

  Referring first to Figures 8 and 9, when considering a point on a document, when the optical prism is near the document, the image is almost in the same position as the point on the document. the

  as the optical prism moves away from

  Although the deflection angle is always the same (as shown in Figure 9), the apparent image now moves towards the right side, or small side of the prism. In other words, the deviation of

the image x depends on tg 6-x y.

  with 6 = (deflection angle through the prism)

  y = distance between the document and the prism.

  Since 6 is fixed by the refractive index of the prism material and the angle of the prism, the value

of x simply depends on y.

  If we view a pair of views such as a pair of stereo photos, through a pair of prisms arranged one above the other with the thin end of one near the thick end of the the other, as shown in FIG. 10, as these prisms move away from the document according to the perpendicular, the image

  right, seen through the prism A, and the left image

  che, seen through the prism B, will seem to move

  towards each other, then meet each other, then

beyond one another.

  If the panel containing lenses is mounted with these prisms and if the refractive index and the prism angle are correctly chosen, these images can be made to meet when the lenses of the viewer are at a proper distance from the lens. document

2 6 1 5633

to watch.

  In practice, since it is desired that the central point of each image coincides with the axis of symmetry of the viewer, the condition concerning the deflection is the same as for the edge of the Fresnel lenses 12 and 14, provided that that the refractive indices are the same. Therefore, the prism angle must be

also 24 '.

  With such. provision, we can now do without the support, normally necessary to hold the lenses and stereo pair of views and to keep the

  correct position and, instead, all that is required is

  12 and 14 and the device 50 for finding the focus distance that the user will hold of a

  hand and the pair of stereo views he will hold from the

to be hand.

  Preferably, the prisms A and B shown in FIG. 10 are obtained as parts of lenses of

  Fresnel, as shown in Figure 11.

Claims (6)

  1. Viewer (10), characterized in that it   carries a pair of lenses (12, 14) through which the user views a pair of stereoscopic views (22), means (20) for holding a pair of stereoscopic views (22) behind the lenses (12, 14). ) such that the distance between the lenses (12, 14) and the pair of stereoscopic views (22) is less than the focal distance of the lenses, so that an enlarged virtual image is seen; each lens (12, 14) having dimensions, in width and height, at least as large as the corresponding dimensions, in width and height, of each view (22) of the pair of stereoscopic views, so that the users   can go from people with presbyopia to people with   each person holding the viewer (10) at a correct distance from the eyes so that the focusing of the images allows this person to see the entire image, the spacing, in the width direction between the images. optical axes of the lenses being such that the rays originating from the image on the left and the image on the right and emerging from the lenses at the junction (15) between the two lenses (12, 14) are substantially parallel, so that it is not necessary for the user's eyes to diverge looking towards the lenses and so that the lenses give the equivalent of optical prisms to bend the images that the user sees   in a scene that directs outward in a direction   in front of the lenses which is an extension of the direction defined by the pair of stereoscopic (22) and the lenses (12, 14).   2. Viewer according to claim 1, characterized in that the lenses (12, 14) are Fresnel lenses.   3. 'Viewer according to any one of the claims   tions, characterized in that the pair of   stereoscopic views is a pair of photographic views   c; and in that means are provided for mounting said pair at a predetermined distance behind the lenses.   4. A viewer according to claim 1 or claim   2, characterized in that it comprises a means   (50) focus distance search, for   put the user to place the stereo view pair   copics at the desired distance behind the lenses (12, 14).   5. A viewer according to claim 4, characterized in that the means (50) for setting distance search   the point comprises a pair of transversally arranged prisms   so that the center points of the image on the left and the image on the right seem to coincide   the views are at the desired distance.   6. Viewer according to claim 5, characterized in that the prisms are molded in one piece with the lenses.