TR202000238A2 - Method for reducing interlayer interference in multilayer holograms. - Google Patents

Abstract

The invention relates to a method that enables the calculation and projection of 3D holograms that are constructed to be multi-layered. In particular, the invention is a method for reducing the interlayer interference in holograms, by randomly selecting the phase of the image to be created in each layer, for determining the image layers and the distances of those images to be projected, enabling the creation of multi-layered or sliced 3D volume images. It is related to

Description

DESCRIPTION INTERFERENCE BETWEEN LAYERS IN MULTI-LAYER HOLOGRAMS METHOD TO REDUCE Technical field to which the invention relates: The invention is based on the calculation and analysis of 3D holograms designed to be multi-layered. It is related to the method that allows the projection to be made.

In particular, the invention is to create multi-layered or sliced 3D volumetric images. of the image layers that provide and creating multi-layered 3D volumetric images. In the holograms that provide interlayer interference, it will be created in each layer. It relates to the method for reducing the phase of the image by random selection.

Known parts of the technique: Holograms, which we can define as the recording of light falling on a living or object, are three-dimensional (SB) images. Holography is the name given to the method of producing holograms.

Since holograms contain depth and parallax, it can be used to view the surrounding and background of the subject. It allows objects to be seen in greater depth. For this reason, the image It makes it possible to be seen from many angles and depths. Today, holography for image transmission from real life to three-dimensional (SB) projections. becomes a usable path. However, holography has some difficulties. A lot layered holography is limited to only a few planes, and complex images are It remains difficult to incorporate into depth control. In this context, three dimensional images at different distances, with high-resolution Being able to produce and protect is one of the biggest problems.

Computer-generated holography (CGH), the ultimate spatial control of light in 3D It is an important tool for This control is checked by the expected applications of the SB demonstration. has been popularized. However, current CGH display technology still in terms of the number of planes, the depth of field and the resolution of the overall projection. he is angry. digitally generated that does not require real objects to create a hologram Synthesized holograms also offer the possibility of SB dynamic Video projection.

True BB holography plus full depth control and dynamic projection it also requires skills; but these requirements are limited by high interference.

The main difficulty here is to get all the information corresponding to a complex 3D image. storing in the 2D form of the hologram, and the projections of different depths The end result is to reconstruct the entire original 3-D image, without contaminating it.

In the state of the art, many studies have been done for SB holography. However, this developments and studies are not enough to solve the basic difficulties. Patent file no. In the summary part of the invention that is the subject of the application hologram consisting of clear reflective reflectors By mastering the 2D (two-dimensional) hologram image acquisition technique of image reflectors, 2D deep (2D depth) and S3D images in the vertical plane of images and reflectors (stereoscopi 3D) real 3D image reflecting hologram perception In order to enable the creation of SSD (stereoscopi 3D) real 3 dimensions based on image acquisition technique (sources in description), 1.5 and 7.5 degrees By placing the second reflector behind the first reflector with an angular difference, 2D deep and on the mirrors as a result of mirroring real SSD images in the viewer based on obtaining real SSD deep images. One step ahead of this technique In addition to the angular reflective models, without any corners, It is unique in that an unlimited number of images can be placed on the cone model without interruption. It is designed as a model” information is included. Patent file no. In the summary part of the invention that is the subject of the application It is a two-dimensional hologram image acquisition device that allows it to be perceived as foil-coated reflective surface struck by the image from said first projection, film-coated reflector on which the image from said reflective surface falls surface, depth to the hologram image in the area under said reflective surface A second projection positioned to create a second image that will add color, It contains a light source whose intensity and position can be changed by the device” information. is located. Patent file no. In the summary part of the invention that is the subject of the application It is related to the configuration that enables the playback image to be converted into a hologram.

The mentioned configuration is displayed on the screens of mobile devices such as mobile phones and tablet computers. It has been developed to convert the played image to a hologram. Said The structuring basically consists of the main body and the main body in a monolithic structure, which contains all the elements. contains a foil that converts the played image to a hologram” information.

As a result of the preliminary research on the known state of the technique, “U87548360” Patent file no. In the invention subject to the application, digital data a method used to produce many of the most common types of holograms and is mentioned in the device. In this invention, the data is completely a 3-D (animated) model. as a computer or from a real 3-D (moving) object or multiple 2-D cameras shot from the scene from multiple different camera positions produced from images. This invention has been made using traditional methods. restricted or full parallax main transmission, known as H1 holograms that can be copied or reflection type composite holograms. Patent file no. In the invention that is the subject of the application, three-dimensional An apparatus and method used for displaying images are mentioned. This In the device of the invention, real-time and three-dimensional motion from a single light beam Active image reconstructor is used to create holograms. Meet The device in question has a compatible light-ray generator that produces the light beam and a light beam that expands the light beam. it has a job expander. A digital micromirror device absorbs the extended light beam. It performs holographic conversion by converting it to a holographic light beam. a lens, receives and modifies the holographic beam of light. An image reconstruction unit, modulated It creates a three-dimensional holographic image from a holographic light beam.

In the state of the art, in 3-dimensional space with computer-generated methods The light beam can be focused at desired points. However, the method basically simultaneous It is not suitable for making images in many slices and at most 2-3 pieces at a mirror time. hologram for images as simple as just dots can be created.

In the state of the art, 2 images of similar complexity are displayed on the computer. Calculation of the created hologram can be done. However, in these studies the number of layers could not be increased above two. In this case, a full 3D There is no mention of the hologram.

In the state of the art, intensive efforts aimed at SB holographic projection However, current methods can be used in several planes, at a narrow depth of field, or at low It is limited to creating images with high resolution. These holographic images, only a few layers allow for production. That is, an object In order to display it, it must be divided into thousands of layers. However, available Only a few of these layers can be produced with hologram technologies. Besides The images produced can be viewed in a very narrow space or are too low. is in resolution. In other words, the object cannot be fully displayed and The object seen is not similar to the object to be viewed.

As a result, due to the above-mentioned negativities and existing solutions It is necessary to make an improvement in the relevant technical field due to the inadequacy of the is locked.

The purpose of the invention: The most important aim of the invention is to ensure that random vectors are perpendicular to each other. is to successfully prevent interference between image layers by using

Another important aim of the invention is to create holography while creating a 3D object. to be able to store its details in a 2D way and while doing so, the neighboring layers It prevents it from overlapping with other layers.

With the method that develops an important aim of the invention, without using any mask, It is shaping directly with laser. In this way, with ions or electrons A much cheaper method is obtained than shaping the material by abrading. is being done.

Another object of the invention is to avoid overlap between layers and This is achieved by randomly selected image phase for each layer in a controlled manner. is to do. In this way, the random wave phases are transferred to the image created in the layers. It can be controlled without causing any damage.

Another object of the invention is to use ultrafast laser pulses at extremely high frequencies. shaping directly with laser, without using any mask is to be done. Thus, much more efficient than what happens in a single, massive laser pulse, It is ensured that the material is processed quickly and with much less thermal error.

Another purpose of the invention is to locally (locally) detect the Fresnel scattering seen in lasers. aims to reduce. In this way, it will enable to dominate each layer produced. random wave phases, no damage to the image created in the layers. can control without

Another object of the invention is that although it uses SLM technology, the hologram similar to any holographic medium, independent of its holographic medium. repeating the displays.

Another object of the invention is the interlayer interference in multilayer holograms. It is fundamental progress towards reducing In this way, multi-layer sliced 3D volumetric images can be created.

Another object of the invention is that it is applicable to any holographic medium, whether SLM or is not limited to a specific technology like this.

One object of the invention is the volumetric unit, which can be divided into two parts as source and screen. imaging makes the resource part feasible.

Another object of the invention is to use the holograms created to be independent of the angle. is viewable.

Another object of the invention is that for each depth the random phase is It provides random phase addition without changing the image projection. This Thus, the wavefront is localized to reduce Fresnel diffraction to Fourier holography. is predetermined.

Another aim of the invention is laser-material processing, 3D printers, medical such as display systems for vehicle drivers or pilots. where computer-generated holograms are already used or may be used can be used in a wide variety of fields.

Another object of the invention is dynamic holographs in real time and video quality. is the development of a method that can be used to produce

Another object of the invention is medical imaging, air traffic control, modern electro-optics. The devices are widely used in microscope studies, laser-material interaction studies. is the development of a method that can be used in fields.

The structural and characteristic features of the invention and all its advantages are given below. and it is clearer thanks to the detailed explanation written by referring to these figures. will be understood as For this reason, these forms and detailed explanations are also included in the evaluation. should be taken into account.

Description of figures: FIGURE 1; Fresnel suppressed interlayer interference with the method of the invention. It is the drawing that gives the image of the steps of obtaining the hologram.

FIGURE -2a; Formation of the holographic reflection of the original object with the method of the invention It is the drawing that gives the image of the steps.

FIGURE -2b; Multilayer 3D with Fresnel hologram of the inventive method It is the drawing that gives the image of the steps of obtaining the projection simulation.

FIGURE -2c; The graph of the normalized vector dot product used in the method of the invention. is the drawing that gives the image.

FIGURE -2d; The planes obtained by the method of the invention were not added to the random phase. and is the drawing that gives its appearance after it has been added.

FIGURE -3; An image of a sample hologram created by the method of the invention. is the drawing.

Description of the invention: The invention is based on the calculation and analysis of 3D holograms designed to be multi-layered. The image to be created, which allows the projection of determining the layers and the distances to be projected on those images, random selection of the phase of the image to be created in the layer and multi-layer or multi-layered, enabling the creation of sliced 3D volumetric images It is a method for reducing interference between layers in holograms. Realistic multi-layered or slices for the creation of a 3D hologram projecting (projecting) a number of images simultaneously in tandem requires. However, projecting multiple images from the same hologram In this case, these images are mixed with each other. Therefore, to date holograms can have at most several layers. With the method of the invention, each This problem is solved by randomly choosing the phase of the image to be created in the layer.

Amplitude information of the image at each point, appropriate selection of the wavefront condition is not affected. However, random phase neighbor and all other images neutralizes their projections.

The method according to the invention is essentially perpendicular to each other of random vectors. successfully prevent interference between image layers by using it provides.

In the method of the invention, firstly Fourier and Fresnel holography stacked Fresnel zone are joined using plates (FZP). Locally determined Fresnel diffraction being flat at depths, FZPs are added to manipulate the propagation core (kernel) provided with. Thus, Fresnel diffraction is effective in desired image planes. is reduced to Fraunhofer contaminant. In addition to this processing, each image By adding a pure random phase to the plane of the image, the images are mutually randomised. and in this way, interference from one to the other is prevented.

Each image plane is considered an n-dimensional vector in the complex space. can be achieved. Here n is the number of pixels of the hologram and is typically many.

Then, removing the interference between the image planes, this n- is equivalent to demanding that the vectors be orthogonal. This approach is like images to create 38 projections of unprecedented density and volume. It is very important to reflect back to back. Thus, SB projection with low interference 3D, high-resolution, multi-layered, back-to-back images that create Fresnel holograms are created.

The processing steps of the inventive method are the image layers to be created and the by determining the distances to which the images will be projected by a computer is starting. Then, random phase phases are performed by the computer on each image. is added. The n-dimensional dimension corresponding to each image layer thus obtained vectors are statistically orthogonal to each other (Figure 2). This steepness also It eliminates wave interference and thus interference. Random phase added The holograms of the layers are calculated independently of each other. Each The Fresnel Zone Plates corresponding to the focal lengths of the layer, calculated superimposed on holograms. The resulting holograms are also When added, a phase type hologram consisting of a single layer is revealed. This When the hologram is projected with a reflector, all the images used in the calculation are 3 It can reflect into dimensional space without interference between layers.

If the process steps are to be detailed, it can be seen that the method, which is the subject of the invention, consists of four steps. application is shown in Figure 1. This method is only a part of the subject of the invention. It is an algorithmic representation and the same or similar results can be obtained with other algorithms. can be done. In the first step, a group of target images is created that creates the desired 3D projection. is received by the computer. Each image is preprocessed with a random phase added. is being passed through. In the second step, each image is converted to Fourier CGH (kinoform) It takes several iterations to create it. 3D targeted to each to project an image plane of the projection and use a set of kinoform Fi(g, n) An Iterative Fourier Transform Algorithm (lFTA) to construct is being implemented. Which is fast enough for real-time applications for this operation. computer generated holograms), projection a fresnel zone to shift it to the focal plane of the corresponding fresnel zone plate plate (FZP) phase. So the fresnel zone plate phase is added. In the fourth step, the translated holograms are created with a single complex value. (complex) Fresnel is added in complex form to create the hologram. This The kinoform operator is used for the addition operation (superposition). Complicated after superposition, the phase of the resulting sum is the final hologram. is used. The final hologram is then displayed with a viewing medium/screen. is displayed. This media/screen does not contain any media used in the imaging process. Could be the viewer. is being done. Forced to the amplitude constraint after the inverse Fourier transform, the Fourier conversion is done. Then the opposite is done.

If any loop condition is met, the IFTA loop is exited and the processed Phase addition is performed on images with Fresnel Zone Plates. High To create quality images, the phase of the source image is transferred to each IFTA iteration. is being changed. For further optimization, the width of the source image to its weighty addition and the image of the hologram produced in this iteration is being changed. Number of iterations per image Root Mean Square for that image The decision is made according to the error (RMSE) value.

Wave surface shaping at each focal plane only requires many ZBs. not only to allow the hologram to form a single SB hologram, but also In order to prevent the added random phase from distorting the image to which it was added, is used. If the reconstructed image, as in Fourier holography, If it had a flat wavefront at the focal plane, this would be almost automatic.

But Fourier holography is limited to the far field. Fresnel holograms are almost It can work from any distance. For this reason, it is a space reflecting a complex field distribution. The Fresnel hologram is calculated. Fresnel hologram calculation process First of all, the image layers to be created and the images to be reflected distances are determined. These determinations are made using Fresnel diffraction (equation -1). is being done.

W(x›)”iz) = ;ejg("l+)'2)ff°o {H(G.i])e-II_;(52+"2)} 1“ -°° (1) .211 ,__ i Here, 2 shows the distance between the image and the hologram, while (x,y) and (En) respectively. are the spatial coordinates on the image and hologram planes, H(F,,ri) in the hologram is the complex field distribution, and A is the wavelength.

The main difference from a Fourier hologram is the presence of the term 61% (E2 + n2). This term, 2 = can be canceled in a certain plane, this is the Fourier of Fresnel diffraction in that plane. corresponds to reduction to transformation.

For this purpose, the H(E,n) hologram is H(g,ri) = F(ig,n)e_ji (E2+ 112). are held. Here F(E_,,n) is the desired U(x,y) image and then Express the Fourier hologram of the product of the random phase (e_1$(xsy)) to be elaborated. is doing. The second-order term added is the effect of the parabolic propagation kernel. By resolving in the zo plane, in this particular plane, the reflected field has a Fourier shape as a form. It allows it to be reduced to look like a hologram. From this transformation Then the image projected on the 20 plane is calculated using equation 2. w (x,y,zoi = 9. ejg(x2+yl) ffm F(g,r])e-jgîfu(xg+mdgdi] (2) For maximum generality and best results, F(g,ri) should be complex.

If we want to keep the method limited to using phase holograms, for experimental demonstration a single SLM will suffice. On a phase-type Fourier hologram, a phase-type FZP superposition; will produce a monoplane phase type Fresnel hologram. This FZP the focus control (20) is for any 2 images beyond the Talbot distance of the desired image. It can be used to reflect the distance in a controllable way.

Next, a single Fresnel hologram with M multilayer projections Its creation is carried out using equation-3.

M .11 2+ 2 HM(5.n)=sglscan)e”TZs“ '” (3) Here, Fs(g,n) contains the Fourier hologram of the image to be projected on the 2 = 23 plane.

Fresnel Zone Plates corresponding to the focal lengths of each layer It is calculated by using equation-4. Here M is the total image number of planes; Fs(g,ri) is random with the image (U(x,y)) to be projected on the 2:25 plane. is the Fourier hologram of the product of the phase (e-Jiislxvyl). Finally, the multi-layered Fresnel The hologram is calculated using equation-4.

HM(G›'T) = - 2 [f: Umy) e-JQÜSUJ') Multiplane hologram ::1 ] lntended iniageRdn om p &se (4) j2 - ”(xg +yri e AZ; dxdy]e Fresnel zone plate 11125“ l' ) Here the random phase (e 14.5( X WY) is different and mutually independent for each plane.

From the calculation of the image projected by the hologram in each plane then the random phase did not distort the image to which it was added, but added to the other images. random excess together prevents unwanted interference between different planes. is seen.

Fresnel Zone Plates corresponding to the focal lengths of each layer After calculating by using equation-4, the calculated holograms superposition is performed (equation-4).

The obtained holograms were added to each other with the computer (complex superpositioning process) produces a phase-type hologram consisting of a single layer. is removed. After this process, the Kinoform operator is applied. Equation-4 The resulting total phase obtained using The reflection of the hologram is provided to be viewed with a viewer.

To show a SB object, as shown in Figure-2b, multiple planes of successive planes are required. a number of images must be projected and all these images must be able to be embedded in the hologram. Each as Fresnel zone plates (FZP) to focus the image on a specific plane. lenses applied one after the other are used. The first important step for this is Fresnel. To reduce diffraction to Fourier transform locally in each image plane to shape the wavefront. Thus, it can reflect on the desired number of planes. The structure of a single Fresnel hologram is reduced to a superposition process. Second The important step is that every mirrored image to avoid mutual interference is to add a random phase to the plane (equation 4).

As shown in Figure-1, a random phase is added to the source images and its As a result, the Fresnel zone plates and the Fourier distances in the '2' direction are adjusted. holograms are created. A created, interlayer interference suppressed Fresnel hologram. Here, the random phase is the perpendicularity of the random vectors. Thanks to this, it provides a serious reduction in the interference between the layers.

An image can be considered an N-dimensional vector where N is the number of pixels.

The random vectors are asymptotically orthogonal at the N -› oo boundary. Central This property, which emerged due to the limit theorem and the law of large numbers, lead to the elimination of traces of images during reconstruction. opens. In this case, interplanetary interference in reconstructed images virtually eliminates the risk.

The holography experiment created by the computer was carried out with the method of the invention.

Although the calculation is done with a computer, the other operations are done with a computer. It can be any kind of calculator such as circuit and so on. Infrared (IR) in the experiment In the case of lighting, a laser source is used to override the separation of the laser beam. and a collimator is used to enlarge the beam spot size. in SLM 800 x 600 pixels, 20 pm pixels to completely fill the displayed hologram A reflective liquid crystal-crystal spatial light modulator in a digital camera has also been used. After modulating the SLM with Fresnel CGH, the parallel, polarized laser reflecting the beam, the beam then optionally emits zero-order diffraction. It is enlarged 3x with a telescope to block it and then projected onto a screen.

The hologram size was chosen as 512 X 512 pixels and the phase quantization was set to 202 levels. is set. The distances and sizes at which images can be projected, larger SLMs and depending on SLM size and pixel dimensions that can be scaled with smaller pixels as it changes. In addition, the method can be used for any light wavelength. 38 The performance of Fresnel CGHs depends on the pixel size and pixel density of the hologram, modulation type, illumination wavelength and amplitude and depends on the phase distributions. Practical limitations, near a reflection-type hologram can affect performance as well as experimental limitations in rendering. This Therefore, it is final to find a precise analytical performance metric that includes all relevant parameters. will be extremely complex. Instead, the performance of 38 Fresnel holograms Two metrics can be chosen that will give good information about First, the root-mean-square error (RMSE), the second is depth-of-field or DoF. First, the image quality. between the source images and the images projected in each plane. It is a measure of similarity. The second metric is based on axial resolution and given relates to the maximum number of separable planes for an image quality. RMSE first is calculated in the corresponding plane for each image and then a SB of all plane results to provide a collective quality metric for the hologram. calculated by the average. This value is a fraction of the plane number of projection quality. It is used to evaluate how it changes as a function. expression in RMSE For a given fault tolerance, the number of image planes can be selected.

In parallel, DoF is used to evaluate axial resolution. DoF, in professional photography, objects are still acceptably sharp commonly used to define the maximum distance between two separate objects used as a metric. Thus, the interference between images occurs in each plane. It can be evaluated with DoF.

The resulting hologram can be used fixed or dynamically. For example, many spatial light modulator (spatial light modulator, SLM), which is also found in the projector Using this, moving 3D holograms can be projected volumetrically. Alternative It can also be permanently written on a phase type optical element. This optic When the element is illuminated with a laser, a spatial light modulator similar to a can create an image.

The number of layers depends on the complexity of the images and the phase type optical element used. determined by resolution. Therefore, the resolution is high enough. As long as the number of layers can be infinitely high.

This method is applicable to all kinds of hologram media, as a spatial light modulator or is not limited to a similar specific technology. Volumetric imaging source and the screen can be divided into two parts. The method of the invention is true volumetric makes the source part of the imaging feasible. subject of the invention Multi-layered or sliced 3D volumetric images thanks to the method can be created.

The holograms created by the method of the invention can be used in terms of monitoring/display. can be viewed independently.

With the method of the invention, medical imaging, air traffic control, modern electro- optical devices, microscope research, laser-material interaction studies. Holographic works that can be used in various fields can be made. Also this holograms created by this method are used in laser-material processing, 3D printers, medical such as display systems for vehicle drivers or pilots. where computer-generated holograms are already used or may be used can be used in a wide variety of fields.

Claims (4)

REQUESTS 1. It is a method that allows calculation and projection of multi-layered and 3-dimensional holograms, and its feature is; - Adding a random phase to each of a group of target images (US) that make up the 3D projection ((35), 7 Adding Fresnel zone plates with the appropriate value (zs) to focus each image layer at the targeted distance in the projection to be created by the computer, 7 It is characterized by obtaining the total hologram (HM) by bringing together the information of all layers, - Displaying the final hologram with a viewer, including processing steps. It is a method that allows calculation and projection of multi-layered and 3-dimensional holograms in accordance with Claim-1, and its feature is; In the process step of obtaining the total hologram (HM) by combining the information of all layers with the computer; 8-1-: Multiplane hologram 5=1 Inlended image an om piaw It is the combination of Fresnel zone plate equation and all layer information by computer. . It is a method that allows calculation and projection of multi-layered and 3-dimensional holograms in accordance with Claim-1, and its feature is; In the process step of obtaining the total hologram (HM) by combining the information of all layers with the computer; It is the application of complex superpositioning to layers. 4. It is a method that allows calculation and projection of multi-layered and 3-dimensional holograms in accordance with Claim-1, and its feature is; The addition of a random phase by the computer to each of a group of target images forming the SB projection, with the random phase added in the processing step, is asymptotically orthogonal to the obtained images at the N -›°° border. . It is a method that allows calculation and projection of multi-layered and 3-dimensional holograms in accordance with Claim-1, and its feature is; in the process of displaying the final hologram with a viewer; is that the imager used can be a spatial light modulator. . It is a method that allows calculation and projection of multi-layered and 3-dimensional holograms in accordance with Claim-1, and its feature is; In the process of adding Fresnel zone plates with appropriate values to focus each image layer at the targeted distance in the projection to be created, by the computer; is the use of a succession of lenses implemented as Fresnel zone plates (FZP) to focus each image on a specific plane.