Abstract:
A device for conversion of an optical radiation flux, the device having a plurality of channels for receiving and transmitting optical flux and the channels having input  6  and output  8  end faces. Radiation, such as light, may be transported with or without reflections from the interior walls of the channels, depending upon curvature or lack thereof. Radiation diverging from a point source can be focused by the device to form large or small images following the output of the device along a longitudinal axis thereof. The input and output faces of the device can be used in reverse fashion. Radiation passing through the device will continue along a directed path in accordance with axial extensions, or continuations, of the individual channel axis.

Description:
FIELD OF THE INVENTION 
   The invention relates to optics and is used for shaping of an optical radiation flux. 
   BACKGROUND OF THE INVENTION 
   Devices are known for shaping or conversion of an optical radiation flux, in particular, for focusing of diverging radiation of a source, changing or transformation of such radiation into quasi-parallel one, focusing of quasi-parallel radiation or its scattering (changing or conversion into diverging one), etc. These devices are usually made in the form of optical lenses or convex or concave mirrors (Physical encyclopedia, Moscow, “Sovetskaya Entsiklopediya” publishing house, 1984, p. 347, 200) [1]. 
   Such devices, when used in the optical systems for generation of an optical image or for changing or conversion of radiation flux emanating from a radiation source, exhibit different aberrations ([1], p. 7), in particular, due to the fact of lens or mirror as a whole participating in light transfer from each point of an object to the image element corresponding to that point. 
   The closest known prior art is in the form of lenses. Optical lenses are similar to the present invention in that they are normally used for shaping or conversion of a flux of paraxial beams impinging upon the lens at small angles to its optical axis. Input flux is shaped as a result of passing through the lens, impinging it on one side and coming out from the opposite side. 
   SUMMARY OF THE INVENTION 
   The present invention provides differential transfer of radiation energy and its corresponding optical information from different elements of the input flux created with a source of light or illuminated object. Because of independent transfer of energy (information) from different elements of the flux (points of an illuminated or luminous object), prerequisites are created for elimination of aberrations inherent to traditional lens systems, and qualitative characteristics of the device depend potentially only on technological possibilities of its manufacture. Another kind of technical result achieved by the device is an “automatic” provision of spatial discretization of the output flux. This facilitates interfacing of the device with digital matrix converters. 
   Two embodiments are proposed of the device. 
   According to a first embodiment, the device is characterized in that it has inlet and outlet end faces connected with a multitude of channels. Channels are made with a possibility of passage or transportation through them of optical radiation with or without reflection from the walls. Channels continuations, i.e., axial extensions, beyond the input and output end faces together have a form of input optical radiation flux perceived by the device, and a desired or required output flux, correspondingly. In one of the embodiments proposed the input end face or both end faces of the device, except for input and output openings of the channels, has a coating made of a material non-transparent for optical radiation in the range of wavelengths used. 
   According to the second embodiment, the device has input and output end faces connected with a multitude of channels made with a possibility of passage or transportation through them of optical radiation with or without reflection from their walls. Channels continuations, i.e., axial extensions, beyond input and output end faces together have a form of input optical radiation flux perceived by the device, and a desired or required output flux, correspondingly. Walls of the channels and spaces between them are made of a material non-transparent for optical radiation of the range of wavelengths used. 
   Thus, both embodiments are similar in that they have multitude of channels for transportation of the radiation from input to output of the device, the form of the input flux (beam), with which the device is intended to work, and the form of the output flux (beam), into which the input flux (beam) of optical radiation should be transformed, are determined by orientation of the channels&#39; ends from the input and output sides of the device (from the side of its input and output end faces). Parts of the channels situated between their end portions serve to conjugate the end portions. 
   The embodiments are differing in the way of elimination of radiation transportation from the input to output of the device through the medium filling out space between the channels. In the first embodiment, to this end a coating is applied on one or both end faces, which is non-transparent for radiation in the range used (the input and output openings of the channels remaining exposed). In the second embodiment, walls of the channels and spaces between them are made of a material non-transparent for optical radiation in the range used. 
   The particular cases of the device embodiments described below may be executed in both variants. 
   The channels may be evacuated or filled up with air or other gaseous medium. In this case, radiation losses on transition through the channels will be small. 
   The channels may be filled up with a medium transparent for the radiation used, which has density above that of the walls. In this case, conditions may be met for a total internal reflection during radiation propagation through the channels. 
   The channels may be made with longitudinal axes curved along generating lines of coaxial barrel-shaped surfaces. At that, when extensions or continuations of longitudinal axes of the channels from the input and output end faces of the device are intersecting at points located on an extension or continuation of the longitudinal axis of the device, the latter is able to perform focusing of divergent radiation from a point source. If, however, continuations or extensions of the longitudinal axes of the channels from the side of one of the end faces of the device intersect at a point located on the extension or continuation of the longitudinal axis of the device, while the continuations of longitudinal axes of the channels from the side of the other end face of the device are parallel to the longitudinal axis of the device, the device effects transformation of divergent radiation from the source into a quasi-parallel one or, vice versa, focusing of a quasi-parallel radiation. 
   With the above construction of the channels, they may have cross sections constant with length or cross section changing in size in the same manner as dimensions of the device as a whole in a transverse direction. 
   Part of the device adjacent to its longitudinal axis may be made non-transparent for the radiation used. Because of this, when the device is used for radiation focusing, dimensions of the focal region decrease longitudinally. 
   The device may be made also in such a way that continuations or extensions of the longitudinal axes of the channels from the side of one of the end faces intersect in a point located on the continuation of the longitudinal axis of the device or are parallel to the axis, while continuations or extensions of the longitudinal axes of the channels from the side of another end face of the device diverge from the longitudinal axis of the device. In this case, the device generates scattered radiation from radiation having already certain angle of divergence, or from quasi-parallel radiation. 
   The device may be used also for turning or bending of the radiation, in which case it may have a longitudinal axis with one or several bends and channels equidistant with it. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG.  1 —illustrates transmission of the radiation through a single channel at different directions of rays entering into the channel, 
     FIG.  2 —shows basic components of the device, including input and output faces and a plurality of channels each having an inlet end and an outlet end, 
     FIG.  3 —shows an aggregate of parallel input ends of channels and corresponding quasi-parallel radiation flux, 
     FIG.  4 —shows an aggregate of convergent ends of channels with continuations intercepting in point of location of a point source, and shows diverging input flux of radiation, 
     FIG.  5 —shows a device for focusing of an optical radiation from a point source wherein the cross section of the channels is constant along their length, 
     FIG.  6 —shows a device for transforming diverging optical radiation from a point source into quasi-parallel one or for focusing of quasi-parallel optical radiation having a constant cross section along the length of the channels, 
     FIGS.  7  and  8 —are similar to  FIG. 5  and  FIG. 6 , respectively, with channels having transverse dimensions changing with length in a manner similar to cross sectional dimensions of the device as a whole, 
     FIG.  9 —illustrates one embodiment with flat end faces, 
     FIG.  10 —illustrates one embodiment having a central portion made non-transparent to the radiation used, 
     FIG.  11 —shows use of the device for generation of an object&#39;s image, 
     FIG.  12 —shows transformation of quasi-parallel flux of optical radiation into scattered radiation, 
     FIG.  13 —shows an embodiment having equidistant curved channels. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Operation of the device is based on radiation transmission from an input to an output through a multitude of separate channels. When source  1  ( FIG. 1 ) of radiation is situated within the limits of an axial extension or continuation of an input end  3  of the channel  4 , this radiation (see, for example, beam A in  FIG. 1 ) enters the channel  4  at a small angle to its walls and passes through to the channel output with a minimal number of reflections from the interior walls. Radiation originating from differently situated points (for example, beam B in  FIG. 1 , emanating from point  5 ) enters channel  4  at a larger angle and suffers greater number of reflections, resulting in a greater extent of attenuation. Difference in the transmission conditions of beams A and B is the greater, the smaller dimension d of the channel is in transverse direction. 
   Input of the device consists of its input end face  6  ( FIG. 2 ) comprising aggregate of one of the inlet ends  7  of the channels, while output consists of the output end face  8  comprising aggregate of the other or outlet ends  9  of the channels. In the course of manufacturing the device the ends of the channels  4  are oriented in such a way as to ensure conformance with a shape of radiation beam requiring to be transformed. For that, aggregate of axial extensions or continuations of the channels towards the radiation sources should have the same shape as the beam transformed. Thus, to transform a parallel or quasi-parallel beam  10  ( FIG. 3 ) the axial extensions or continuations  11  of the input ends  12  of the channels of the device should be parallel to one another, while aggregate of their cross sections for the full capturing of the source radiation should be the same as the cross section of the beam being transformed or to include completely the cross section of the beam being transformed. To transform beam  13  ( FIG. 4 ) of diverging radiation from a point or quasi-point source  14  the axial extensions or continuations  15  of the input ends  16  of the channels of the device should intersect in the spot of the source location. Captured and transformed will be just that part of the source radiation which is emanated within limits of the spatial angle formed by aggregate of continuations of the input ends of the channels. Likewise, orientation of the continuations or axial extensions of the output ends of the channels is chosen depending on the required shape of the output beam, while cross-sectional dimensions of the beam are determined by aggregate cross section of the output ends  8  of the channels. 
   Shape of the parts of the channels located between their end portions is chosen under the condition of smooth alignment of the end portions. 
   Through the central channels, i.e., adjacent to the longitudinal axis of the device, which have small curvature or are rectilinear, radiation may be transmitted without reflection from their walls. 
   In both embodiments described above, the invention may comprise channels  4  for transportation of the optical radiation, which have cross section constant through their length ( FIG. 5 ,  FIG. 6 ). In this case, the device is assembled of separate like channels, for example, glass capillaries, using some kind of separating elements to impart desired shape to the channels and the device as a whole, similar to method of X-ray lenses assembling according to my U.S. Pat. No. 5,192,869 (publ. 09.03.93) [2]. According to the first embodiment of the device, solid separating element with openings for the ends of the channels may function as a part of the end face non-transparent for radiation of the range used. The device according to the second embodiment may also be manufactured by a technology disclosed in my earlier mentioned patent, which envisages filling up of space between channels with a compound instead of using separating elements. According to the second embodiment of the invention proposed above, the compound should be non-transparent for the optical radiation used. 
   Channels  4  may have their cross section changing in size ( FIG. 7 ,  FIG. 8 ) in the same manner as cross-sectional dimensions of the device as a whole. In this case, technology of glass slugs drawing is applicable for manufacturing of the device, as disclosed in my Russian Federation patent No. 2096353 (publ. 20.11.97 [3]). This technology, with which the process may be automated to a great extent, is a more progressive one in comparison with the assembly method. However, the most promising one is a technique used for manufacture of so called integral X-ray lenses (see my Russian Federation patent No. 2164361, publ. 20.03.2001[4]; and my U.S. Pat. No. 6,271,534, publ. 07.08.2001[5]), allowing construction of devices having a large number of the channels in micron and submicron diameter range. On completion of the manufacturing process stages according to [4] or [5], a monolithic device is obtained with end faces formed by melting together the ends of the channels. To finish manufacturing of the device according to the first embodiment proposed, a material non-transparent for the radiation used is deposited (for example, sprayed) on the surface of one or both end faces formed by spaces between the channels. In particular, this may be sprayed, radiation reflecting material. In this case, there is no need to take special measures to avoid its getting into the channels and depositing on their walls. To produce the device according to the second embodiment, tubular slugs of the future channels are used made of material non-transparent for the radiation used, for example, stained glass. 
   In all the cases of the embodiments described, it is important for its proper operation to exclude transportation of the radiation from input to output of the device through the medium used for filling up spaces between the channels. This is provided for with the above measures ensuring involvement in generation of the output flux only of the radiation transported through the channels. From the input side, the channels ensure the selectivity required, while their output ends direct the radiation as required. If no such measures are taken, the radiation is able to penetrate channel walls from one channel to another, propagate through spaces between the channels, and reach the output of the device not through exit openings of the channels or through them, but in arbitrary directions. Experiments demonstrate that as a result of this, desired effects are not achieved, in particular, those of focusing or shaping of quasi-parallel beam. 
   In  FIGS. 5 to 9  vertical hatching denotes spatial zones formed by aggregate continuations or axial extensions of the ends of the channels  4  beyond the input and output end faces. Those zones have form, correspondingly, of input flux of optical radiation received by the device, and of the required or desired output flux. For all the devices invertibility takes place. Thus, for the focusing devices shown in  FIG. 5  and  FIG. 7 , either one of the end faces may be the input face, while the other will be the output face. The devices shown in  FIG. 6  and  FIG. 8 , on feeding of diverging flux of radiation from the source, for example, point source  14 , from the side of left end face generate in the output a flux of quasi-parallel radiation, while on feeding the same radiation from the side of the right end face generate focused radiation flux. The devices shown in  FIG. 5  and  FIG. 7  have a barrel-like shape, and the devices shown in  FIG. 6  and  FIG. 8  resemble a half-roll. In both cases, center lines of the channels, except those in the core (adjacent to the longitudinal axis of the device) are curved along generating lines of barrel-shaped surfaces. 
   The end faces of the device may be rounded, like both end faces of the devices in  FIG. 2 ,  FIG. 5 , and  FIG. 7 , and left end faces of the devices in  FIG. 6  and  FIG. 8 , or flat, as right end faces of the devices in  FIG. 6  and  FIG. 8 , or both end faces of the device in  FIG. 9 . It is expedient to make the end faces flat when radiation entering this end face or emergent from it is quasi-parallel, as well as in cases when the channels are evacuated or filled up with gaseous medium other than air. In this case the end faces are coated with a film transparent for the radiation used to ensure airtightness. 
   The channels may be filled up with a medium having density higher than that of their walls. As such channels, for example, optical fibers may be used with quartz core. In this case, losses of radiation energy during its transportation through the channels may be diminished due to utilization of the full internal reflection phenomenon. 
   When using the device proposed for focusing of optical radiation, the focal region may be strongly diffused longitudinally due to the presence of rectilinear or slightly bent central (adjacent to the longitudinal axis of the device) channels. Focusing quality may be increased by the way of making the part of the device adjacent to its longitudinal axis non-transparent to the radiation used. This may be achieved both by making this part  17 , as shown in  FIG. 10 , solid of non-transparent material, i.e. containing no channels, and by blocking inlet or outlet openings of the central channels after manufacturing of the device containing such channels. Decrease in the longitudinal size of focal region  18  is achieved due to the fact of it being formed only by radiation of peripheral channels emergent at an angle to the longitudinal axis  19  of the device. 
   By analogy with traditional optical lenses and taking into account the functions performed, the device proposed in the embodiments considered may be named a lens. When using such lens as a means for image generation of a flat object, each channel serves for transmittance of information on one element of the object only, situated on an axial continuation of the input end of this channel. As it was stated above, influence of elements located aside of this continuation is the weaker, the smaller the diameter of a separate channel. On using the device  20  ( FIG. 11 ) of the type shown in  FIGS. 5 ,  7 , and  9 , image  21  of the object  22  may be obtained in any plane perpendicular to the longitudinal axis  23  of the device  20 , to the right of its output end face (both to the right and to the left of output focus  24 , which is defined as the intersection point of axial continuations of longitudinal axes of the channels from the outlet side). Object  22 , whose image is generated, may be located both to the right and to the left of input focus  25 , which is defined as intersection point of continuations of longitudinal axes of the channels from the input side. In the case shown in  FIG. 11 , object  22  is located to the left of the input focus  25 , and the image generated—to the right of the output focus  24 , that is, planes of the object and of the image are removed from corresponding end faces to the distances L 1  and L 2  exceeding focal distances f 1  and f 2  (the latter being defined as distances from the inlet (outlet) of the central channel to corresponding focus). 
   The image obtained in this case is “non-inverted”. A dot element of the object corresponds to image element having minimal dimension of the order d(1+2L 2 /L 1 ), where d denotes cross-sectional dimension of the channel (for circular cross section—its diameter). Since usually in image acquisition of macroscopic objects L 2 &lt;&lt;L 1  (such ratio also takes place in traditional photography), a minimal image element has dimensions of the order of channel diameter d. 
     FIG. 12  shows a particular embodiment of a device  26  for transformation of quasi-parallel flux  27  of optical radiation into scattered radiation  28 . In this case, output ends of the channels  4  are diverging in different directions away from the longitudinal axis of the device. 
   The device  29  shown in  FIG. 13  is made in such a way that the longitudinal axes of its channels are equidistant and curved for bending the beam  30  of a quasi-parallel beam of radiation being transformed into a beam  31 . 
   In all the cases of the device embodiments described it is important for its proper operation to exclude transportation of the radiation from input to output of the device through the medium filling up spaces between the channels. As mentioned above, this is achieved by utilization of a coating on one or both end faces of the device (except for the inlet and outlet openings of the channels), which is non-transparent for the optical radiation used, or by making the channels walls and spaces between them of a non-transparent material. Due to this, only radiation transported through the channels takes part in the formation of output flux. From the input side, the channels ensure required selectivity, while their output ends impart to radiation the direction required. Experiments demonstrate that if no such measures are taken, the radiation is able to penetrate channel walls from one channel to another and propagate through spaces between the channels, in the result of which no effects are achieved, in particular, of focusing and shaping of quasi-parallel flux. 
   INDUSTRIAL APPLICABILITY 
   The device proposed may be realized in practice in any of the possible embodiments described, depending on required nature of transformation of the optical radiation flux, technological possibilities and other reasons for these or other preferences. 
   BIBLIOGRAPHY 
   
       
       1. Physical Encyclopedia, Moscow, “Sovetskaya Entsiklopediya” publishing house, 1984. 
       2. U.S. Pat. No. 5,192,869 (publ. 09.03.93). 
       3. Russian Federation patent No.2096353 (publ. 20.11.97). 
       4. Russian Federation patent No.2164361 (publ. 20.03.2001). 
       5. U.S. Pat. No. 6,271,534 (publ. 07.08.2001).