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'''SOGOKON' A. B.'''
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= Lippmann’s photography on dichromated gelatin plate =
  
'''LIPPMANN PHOTOGRAPH'''
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Sogonkon' A. B.
 
ON THE LAYERS OF THE BICHROMIZED GELATIN
 
  
Are investigated the spectral characteristics of the Lippmann images, obtained on the layers of the bichromized gelatin (BKHZH). It is shown that the color of image depends not only on the wavelength of emission, but also on its intensity. This is connected with the heterogeneous swelling of gelatin and with a change of its structure in the nonirradiated sections with the rapid dehydration.
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{{Note | This article was transcribed from the text in the [[Media : Sogokon Lipp phot on DCG.pdf | file available here]].}}
 
The uncommon properties of Lippmann photographs on BKHZH can be    used for preparing the selective mirrors, for mapping of graphic information, and also for registration and image processing.
 
  
Is known [1] the method of obtaining the colored images, based on the registration of standing waves in the volume of thick transparent photographic emulsion. The period of the registered interference structure is unambiguously connected with the wavelength of that falling to the layer of emission, which ensures the correct color reproduction of the photographed image with the illumination by its white emission. Because of the great technical difficulties in its time this method did not obtain wide application.
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The research of properties of Lippmann’s images obtained on dichromated gelatin plate shows that image color depends on wavelength of radiation as well as on its intensity. It relates to heterogeneous swelling of gelatin and structural changes of its unirradiated parts at fast dehydration.
  
The development of holography led to the creation of the fundamentally new technique of experiment and new recording media. Appeared communications about the record of Lippmann photographs on the contemporary emulsions of the type LOI-2 [ 2,3 ] and on the layers of the bichromized gelatin (BKHZH) [ 4,5 ].
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Unusual behaviour of Lippmann’s images on dichromated gelatin plate may be used for producing selective mirrors for reflecting graphic information and date registration and image processing.
Purpose of this work - study of the special features of the Lippmann photographs, obtained on the layers BKHZH, the mechanism of shaping of images and possibilities of their practical application.
 
  
'''Procedure and the results of the experiment'''
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== Introduction ==
  
For the preparation is layer BKHZH the basis it is undertaken the method Lina [6]. The holographic plates Of pe-2 and LOI-2 they fixed in the acid fixative, washed in the running water and dried at room temperature. The sensitization of the dried plates was conducted directly before the exhibition. For this plate was immersed on 5-15 min in 1-5%- ache the solution of dichromate of ammonium and after its runoff dried in the jet of hot air or in the cabinet drier at a temperature 100-150°. Duration of drying 3-5 min.
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There is [1] a method of obtaining color image based on registration of standing waves in the volume of thick transparent photographic emulsion. Period of registered interference structure is unambiguously related to the length of the wave of radiation influencing the plate. This assures right color rendering of photographed image if disposed to white radiation. This method wasn't widely adopted because of big technical problems.
  
[[Image:LippmannFig1.jpg]]
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Development of holography leads to creation of a totally new technique of experiment and new registering mediums. There appeared some announcements that Lippmann’s images have been tried on modern emulsions like ЛОИ-2 [2,3] and on dichromated gelatin [4,5].
  
Fig. 1. Installation diagram for the contact printing
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The aim of this work is to investigate the behaviour of Lippmann’s images made on dichromated gelatin as well as mechanism of image formation and possibilities of its application on practice.
Lippmann photographs; 1 - luminous source
 
(laser or mercury-vapor lamp), 2 - lens, 3 - negative,
 
4 - layer BKHZH, 5 - the mirror
 
  
The installation diagram for the printing of Lippmann photographs is given in Fig. 1. They direct the extended laser beam to the negative, located before the recording medium, the passed emission is reflected from the flat mirror and, being extended in the opposite direction, is formed in the volume of the recording medium the standing wave, whose amplitude depends on the transmission of negative. As the radiation sources were used the lasers LPM-YY (442) and LIE -21 (337 nm) and mercury-vapor lamp DRSH-2SHCH0 (365, 436 nm). Furthermore, by means of the usual photographic enlarger was achieved the direct projection printing of enlarged images.
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== Method and results of experiment ==
The regime of working the plates exposed practically was differed in no way from the regime of working BKHZH for obtaining the holograms [ 7 ].
 
  
The images, obtained employing the procedure given above, have a number of interesting properties. With the examination of image in the reflected light (a subnormal incidence in the light) different sections of image depending on the density of initial negative acquire different color. Under the transparent sections is obtained the image of dark-blue color, while under the opaque - red. The semitones of negative are transferred by nuances within the limits from the orange to the green. Hence it is possible to draw the conclusion that the period of the interference structure, fixed in the layer BKHZH, depends both on the wavelength of emission and on its intensity.
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Lippmann’s method is basic for making dichromated gelatin plates [6]. Holographic plates ПЭ-2 and ЛОИ-2 were placed into acid fixing solution then washed in running water and dried at room temperature. The plates were sensitized right before exposure. For this the plate was placed for 5-15 minutes into 1-5% solution of dichromated ammonium and after its runoff dried by hot air current at temperature 100-150°C. The duration of drying is 3-5 minutes.  
  
If we arrange Lippmann imprint on the sheet of black paper and to examine at large angle, then usual black and white image is observed. Under the transparent sections of the negative of gelatin it remains transparent, while under the opaque acquires milk-white tone. In this case the image is constructed not due to the luminous absorption, but due to its scattering, which resembles the properties of images on the vesicular materials [8].
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[[Image:LippmannFig1.jpg|center|Image 1. Scheme of device for contact printing of Lippmann’s images. 1 – light source (laser or mercury lamp), 2 – lens, 3 – negative, 4 - dichromated gelatin plate.]]
For investigating the dependence of the color of image on the exposure level on one plate they achieved a number of exposures by the uniform collimated laser beam or photographed the image of sensitometric wedge, and then the spectra of the transmission of the obtained images were measured.
 
  
[[Image:LippmannFig2.jpg]]
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Scheme of device for contact printing of Lippmann’s images is displayed on image 1.  Widened laser beam is directed onto registering medium. The radiation passed through reflected from plate glass spreads in reverse and forms a standing wave in the volume of registering medium the amplitude of which depends of negative passing. As the source of radiation lasers ЛПМ-11(442nm) and ЛГИ-21 (337nm) and mercury lamp ДРШ-250 were used. Besides direct projecting printing of enlarged images was realized with help of a usual photographic enlarger.
  
Fig. 2. Characteristics of Lippmann the image:
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Processing mode of exposured plates hardly differed from that of dichromated gelatin for
and, g - dependence of the spectra of the transmission of the images from the exposure level with the record by the emission
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obtaining hologram [7].
heliumcadmium (442 nm) and nitric (337 nm) lasers;
 
b and d - dependence of the density of image on the exposure
 
for the same wavelengths; C - the dependence of the color of the image from the logarithm of exposure (curve 1 - 442, curve 2 - 337 nm); e - dependence of the half-width of the spectra of the transmission of the images from the exposure (1 - 442, 2 -337 nm)
 
  
Fig. 2 depicts the spectral characteristics of the images, obtained on the plates Of pe-2, sensitized by the 1%- by the solution of dichromate of ammonium during the exhibition by the emission of lasers LPM-YY (Fig. 2, A) LIE -21 (Fig. 2, g). From the analysis of spectra follows that depending on exposure level the width of reflection spectra (Fig. 2,e) changes, the wavelength of the maximum of reflection (Fig. 2, c), and also the density of image (Fig. 2, b, d). It should be noted that the wavelength of the maximum of reflection with the long exposures does not correspond to the wavelength of the emission of record. This is connected with the fact that in the process of treating the layer an increase in the period of interference structure occurs. The wavelength of the maximum of reflection linearly depends on the logarithm of exposure (Fig. 2, c), which gives the possibility to write down
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Images obtained using the foregoing method have a number of interesting qualities. If watching at an image in reflected light (almost natural light rays falling) different parts of the image get different colors according to density of initial negative. The image gets blue color under transparent parts and red color under opaque ones. Half-tints of negative are reproduced by hues from orange to green. From this follows that interference structure period depends on length of radiation wave as well as on its intensity.
  
[[Image:LippmannEq1.gif]]            (1)
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A Lippmann’s image if placed on a black sheet of paper and watched at broad angle will be black-and-white. Gelatin remains transparent under transparent parts of the image and gets milkwhite under opaque parts. In this case the image is not reproduced by light absorption but its dispersion that resembles the properties of display on vesicular materials [8].
  
where  - the wavelength of the maximum of reflection with the high energy of exposure (wavelength of saturation), H - energy of exposure, k - constant of proportionality, which can be interpreted as the coefficient of the color contrast.
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To investigate the dependence of image color on the exposure within one plate a number of exposures was done by collimated laser beam. There were made also photos of sensitometric wedge image and then spectrums of transmission of the received images measured.
 
With the conversion of the color of image occurs a change in its density (Fig. 2, b, d). These dependences are analogous to the characteristic curve of blackening of the usual recording media. However, the photographic latitude of linear section is considerably less, and in the field of the long exposures is observed the especially large spread of experimental points, which it is not possible to explain by error of measurements. It is possible to assume that the dependence of image in the region of saturation bears the oscillitory nature, for example, as shown in Fig. 2, d.
 
  
'''Mechanism of the formation of the images'''
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On image 2 there are spectral characteristics of images obtained on ПЭ-2 plates sensitized by 1% ammonium solution at exposure by laser ЛПМ-11 (image 2,a) and ЛГИ-21 (image 2, г).  It follows from the analysis of spectrums that spectrum reflection width (image 2, e), length of wave maximum reflection (image 2, в) and density of image (image 2, б, д), change according to exposure amount. It is significant that length of wave maximum reflection at considerable exposure does not correspond to the length of radiation wave of the record. It’s due to increasing period of interference structure at layer processing.
  
In the process of the preparation of plates for the sensitization they prolonged time (about 1 h) find in the water. As a result of this gelatin it swells, long protein molecules untwist and they attempt to form the linear arrays. To molecules, which are been located on surface layer, this succeeds to the larger degree than for molecules, which are located in the depth, since they to a lesser degree experience the resistance of adjacent molecules. In the razbukhshem layer is obtained the heterogeneous tanning, which grows from surface layer to the base layer. The surface molecules of gelatin, which formed the linear arrays, no longer can accomplish work, they occupied energetically advantageous position, while molecules, which are located in the depth of layer, they have a certain reserve of potential energy, since interaction of some with others and with the molecules of tanning matter does not make possible for them to be erected into the linear arrays. Tanning can be determined by value, to the inversely proportional work, accomplished by molecules with the working in the water. Layer is not tanned, if molecules realize entire stored potential energy, and it is tanned, if potential energy with the working in the water does not realize. The potential distribution energy along the thickness of the razbukhshego layer can be schematically presented, as shown in Fig. 3, A.
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[[Image:LippmannFig2.jpg|center|Image 2. Lippmann’s images characteristics: а and г - dependence of image transmission spectrums on exposure amount at recording by radiation of helium-cadmium (442 nm) and nitrogen (337 nm) lasers; б and д – dependence of image density on exposure for the same wave length; в – dependence of image color on exposure logarithm (curve 1 – 442, curve 2 – 337 nm); dependence of half-width of transmission spectrums on exposure (1 – 442, 2 – 337 nm).]]
  
Let us examine the processes, proceeding with swelling of those exposed it is layer. In this case we consider that the photochemical transformations Cr(.VI) into S.r(.III) in the gelatin occur in accordance with the model, described in the work [ 9 ]. The number of photos-seam between the molecules, which were being formed in the antinodes of standing wave, is small with low energies of exposure, summary binding energy between them is also small, and the potential distribution energy of the molecules of the swollen layer takes the form, shown in Fig. 3, b. furthermore, with the prolonged working in the water together with swelling of layer in the knots of standing wave can occur the local dissolution of gelatin, i.e. the hydrated molecules acquire relative freedom, changing the structure of gelatin, but they cannot leave layer because of the tanned sections in the antinodes. In the works [ 10,11 ] it is shown that the structure of gelatin changes both with working of layer in the water and in the process of drying. Therefore with the working by isopropanol a change in the structure of gelatin in the knots and the antinodes occurs differently, i.e. with the rapid loss of water of molecule they do not manage to return to the initial state and they are forced to form the new molecular network, different from that, which is obtained with usual gel-NII - Scientific Research Institute or slow drying. In the knots of standing wave gelatin density decreases due to an increase in the volume of layer, while in the antinodes it increases due to structure change under the action of that forming Of s.r(.III). As a result of gelatin the elasticity loses, and in the layer the increased period of interference structure is fixed. With an increase in the exposure grows modulation of potential energy of the razbukhshego layer. The number of constant-phase surfaces, recorded in the layer, increases (Fig. 3, in, g, d), the width of reflection spectra and displacement into the red region decrease, and diffraction effectiveness rises.
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Length of wave maximum reflection linearly depends on logarithm of exposure (image 2, в)
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what gives possibility to write
  
By a change in the structure of gelatin it is possible to explain the formation of black and white image. The destructured sections strongly scatter light, which gives milk-white form to them.
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<div>
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<p style="float: left; width: 90%; text-align: center;"><math>\displaystyle \lambda - \lambda_0 = k (\log{H_{max}} - \log{H})</math></p>
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<p style="float: left; width: 10%; text-align: center;">(1)</p>
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<p style="width: 100%;"></p>
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</div>
  
'''Consideration of the results'''
 
  
Uncommon properties of Lippmann photographs on the layers BKHZH can be used for preparing the selective mirrors, for obtaining the pseudo-colored slides from the black and white negatives, for registration and image processing.
 
  
The possibility of using the Lippmann photographs as the selective mirrors directly follows from Fig. 2. The wavelength of reflection and half-width depend on exposure level. In this case the reflection coefficient attains 99%, which makes it possible to use such mirrors in the resonators of lasers, in the Fabri-Perot interferometers, and also as the beam splitters in the holographic devices. The cost of them is considerably lower than interference dielectric mirrors, and in this case is a possibility of preparing the mirrors of practically any sizes and creation of any distribution of spectral characteristics in the plane of mirror.
 
  
[[Image:LippmannFig3.jpg]]
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where λo - length of wave maximum reflection at high energy of exposure (wave length of saturation), H – energy of exposure, k – coefficient of proportionality which may be interpreted as coefficient of colors contrast.
  
Fig. 3. Diagram, which elucidates the dependence of the period of the interference structure from the exposure level: and - the distribution of the tanning in the razbukhshem unexposed layer; b, in, g, d - modulation of the tanning in the razbukhshem layer depending on the exposure
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Image color change evokes change of its density (image 2, б, д). These dependences are similar to characteristics curve of nigrescence of simple registering mediums. Nevertheless photographic width of linear region is much smaller. Dispersion of experimental points is especially considerable in regions of high exposure that can’t be explained by measurement errors. We can suppose that dependence of image transmission in region of saturation has oscillating character as demonstrated for example on image 2, д.
  
The pseudo-colored slides, obtained from the black and white negatives, can be used for mapping of graphic information, for example diagrams, tables, graphs. Slides can be demonstrated both in the transmitted light by usual kadroproyektorom and in that reflected with the application of an epidiascope. The second version should be given preference, since with this more fully is used color range and is reached higher high-contrast image.
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== Mechanism of image creation ==
With the printing from the black and white negatives the value [[Image:LippmannEq2.gif]] and [[Image:LippmannEq3.gif]] in equation (1) can be represented in the form
 
  
[[Image:LippmannEq4.gif]]
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Preparing plates to sensitizing they should be placed into water for a period of time (about one hour). As a result gelatin gets swelled and long protein molecules swivel in the way to create linear chains. It relates more to molecules on the surface of the layer than those which are deep in as they are less exposed to strength of adjacent molecules. There appears a heterogeneous hardening increasing from the layer surface to substrate. Superficial gelatin molecules forming linear chains can no longer perform work as they took favorable energetic position. Molecules deep in the layer have some amount of potential energy. Their interaction with each other and molecules of gelatin hardener prevents their forming linear chains. This hardening can be defined as value inversely proportional to work performed by molecules when processed in water. The layer is not hardened if molecules realized their potential. The layer is hardened If they didn't realize their potential energy when processed in water. Distribution of potential energy in the thickness of hardened layer may be presented in diagram form as demonstrated on image 3,a.
  
  and  
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Let’s consider processes taking place at hardening of exposed layers. Here we consider that photochemical transformations Cr (VI) to Cr (III) is realized according to model described in work [9]. At low exposure energies the number of photographic connections between the molecules created in bulge points is also small. Distribution of potential energy of molecules in hardened layer is demonstrated on image 3,б. At enduring processing in water besides hardening of layer in nodes of standing wave there may occur local gelatin dissolution. In other words hydrated molecules get relatively free changing their structure but can’t leave the layer because of hardenings in bulge. Work [10] and [11] describe that gelatin structure change at processing in water as well as at it’s drying. Therefore when processed by isopropanol change of gelatin structure in nodes and bulges are realized different ways. At considerable loss of water molecules don’t have time to return to initial state so they are forced to create a new molecular netting different from that which is created at simple freezing or slow drying. Gelatin density decreases in bulge points of standing due to growth of layer volume and increases in bulges due to change of structure under influence of formed Cr (III). As a result gelatin loses its elasticity. Increased period of interference structure can also be registered in the layer. Increasing exposure involves increasing of potential energy modulation in swelled layer. Number of isophased surfaces recorded in layer increases (image 3, в,г,д). Width of spectrum reflection and displacement to red region decrease but diffraction efficiency increases.
  
[[Image:LippmannEq5.gif]]
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Performance of black-and-white image can be explained by change of gelatin structure.  Unstructured spots cause considerable light dispersion and get milk-white colored.
  
where  - the intensity of light, which falls to the negative,  the smallest density of negative (density of veil),  density of image,  time of exhibition. After substituting these values in (1), we will obtain
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== Discussing results ==
  
[[Image:LippmannEq6.gif]]
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Unusual properties of Lippmann’s photos made on gelatin plates can be used for producing selective glasses as well as for receiving pseudocolor slides from black-and-white negatives and image processing and registration.
  
whence it follows that a change in the color in the Lippmann photograph is linearly connected with the density of negative.
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Possibility of using Lippmann’s photos as selective glasses follows directly from image 2Length of wave reflection and half-width depend on exposure value. At this coefficient of reflection reaches 99% that allows using such glasses in laser resonators, interferometers Fabri-Perot and also as beam dividers in hologram devices.
Recently increasingly more frequently is used the idea of complex spatial distributions of different physical quantities by means of the conditional it is color, for example, with digital processing of images [ 12 ]. To Lippmann photographs on BKHZH this property is inherent by their nature itself. In this case Lippmann "painting" has the advantage that the obtained image can be subjected to further optical working. Examining the pseudo-colored image through the light filter with the passband [[Image:LippmannEq7.gif]], we will observe the details of initial image, which are located in the density range [[Image:LippmannEq8.gif]].
 
   
 
By a change in the wavelength of light filter it is possible to separate the image details interesting, and by changing its half-width - range of densities interesting. If the image, observed through the interference light filter, photographed on the contrasting photographic material, then it is possible to obtain the images of the lines of identical density - equidensities. For the illustration is carry ouied processing the image of planet Jupiter. For this from the astro-negative they printed image with an increase by the layer BKHZH. The obtained image they photographed through the interference light filter with [[Image:LippmannEq9.gif]] = 640 nm and [[Image:LippmannEq10.gif]]= 90A. Fig. 4, and depicts the photograph of initial image, while on Fig. 4, b, C - to a series of photographs with the different angles of the slope of interference light filter, i.e. with the different [[Image:LippmannEq9.gif]]  and [[Image:LippmannEq10.gif]]. It is evident that even under the conditions for the incorrectly set experiment (reconstruction of the wavelength of light filter was achieved via its inclination) on the obtained images it is possible to reveal more interesting details, than on the initial negative.  
 
  
[[Image:LippmannFig4.jpg]]
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[[Image:LippmannFig3.jpg|center|Image 3. Scheme explaining dependence of interference structure on value of exposure: а - distribution of hardening in swelled non-exposed layer; б, в, г, д – modulation of hardening in swelled layer depending on exposure.]]
  
Fig. 4. Isolation of equidensities on the image of planet Jupiter:
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They cost less than interference dielectric glasses. There is also possibility of producing glasses of almost any size as well as distribution of spectrum characteristics within glass plane.  Pseudocolor slides received from black-and-white negatives may be used for transmission of graphic information for example schemes, tables, diagrams. Slides can be projected at passing light by simple slider as well as at reflected light by epidiascope. It’s better to give preference to  the second variant as color gamma is fuller and image contrast is higher then.
and - the imprint of siskhodnogo astro-negative; b - photograph of the Lippmann image, obtained with the interference light filter with the different angles of its inclination in the reflected light; C - the same, but in the transmitted light
 
  
However, with the two-stage process unavoidably are shown distortions and noise, which appear during the first stage of registration. The granularity of images on Fig. 4, b is caused by the granularity of the material, on which is registered initial negative. Therefore the considerably larger volume of information can be extracted with processing of the Lippmann images, obtained with the direct registration. However, sufficiently small sensitivity it is layer FOR BKHZH it does not make possible to directly record the images of other astros-object, except the sun. The direct registration of Lippmann images possibly in biology. In this case the emission of lamp DRSH-2SHCH0 it is completely sufficient for obtaining the images with increase in 30-100x.
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At printing from black-and-white negatives value H<sub>max</sub> and H in equation (1) can be presented as
  
Thus, the Lippmann photographs, obtained on the layers BKHZH with the use of sources of monochromatic light, have properties, substantially different from the properties of usual Lippmann photographs. This is connected with the special features of the recording medium: the period of the fixed interference structure depends not only on the wavelength of incident radiation, but also on its intensity. As a result the possibility of the single-valued conversion of the intensity of light in the color appears. Simplicity of the diagram of obtaining Lippmann photographs, possibility of using the sources with the small length of coherence and high diffraction effectiveness of images open the great possibilities of the practical application of this method.
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<center><math>\displaystyle H_{max} = I_0 t (10^{-D_0})</math> and <math>\displaystyle H = I_0 t (10^{-D})</math></center>
  
In conclusion the author considers as his pleasant duty to express appreciation To v. p. sherstyuk and L. ye. mazur for the valuable considerations, in. By a. kaminskoy and By l. ye. nikishinoy for help in conducting of spectrophotometric measurements and V. n. dudinova - for the kindly furnished astro-negatives.
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from this follows that change of color of Lippmann’s photo is linearly dependent on negative density.
  
'''LITERATURE'''
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Last time in increasing frequency is used the idea of complex spacial distribution of different physical values by conventional colors for example at image digital processing [12].  This quality is inherent to Lippmann’s photos taking in consideration their nature. Lippmann’s coloring method has an advantage: such image may further be optically processed. Observing a pseudo-colored image through a light filter with gating line Δλ we can see details of initial image in the interval of densities ΔD.
  
*1. Lippmann G S. R// Acad. Sci. 1891. V. 112. P 274.
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Details of interest of image may be marked by change of wave length of light filter. Diapason of densities may as well be marked by changing its half-width. If you make a photo of image observed through interference filter on a contrast photographic material you can receive image of lines of same density – equidensite. To illustrate this image of Jupiter was processed. For this the image of astro negative was printed with enlargement on dichromated gelatin plate. Then was made photo of received image through interference light filter with λ=640 nm and Δλ=90Å. Photo of initial image is presented on image 4, a. On image 4, б, в there are series of photos made at different angles of interference light filter incline that is at different λ and Δλ. You can see that even in conditions of incorrectly organized experiment (setting of wave length of light filter is realized by its incline) you can discover more details on received images than on initial negative.
*2. Kostylev G. d. //Pis'ma in ZHTF 1976. Vol. 2. Of iss. 23. S. 1086.
 
*3. Kostylev G. d., Ivanenko L. i.// the theses of dokl. IV All-Union conf. "photometry and its metrological guarantee". M., 1982. S. 119.
 
*4. Sogokon' A. V.// the theses of dokl. IV All-Union conf. "non and uncommon fo- tograficheskiye processes". Blackcap, 1984. Vol. 1 of h. 2. S. 251.
 
*5. Sogokon' A. b.// the theses of dokl. II All-Union conf. the "forming of optical image and the methods of its working". Kishinev, 1985. Vol. 1. S. 125.
 
*6. Lin L n.// Appl. Opt. 1969. V 8. № 5. P 963.
 
*7. Sjolinder S// Photogr. Sci. And Eng. 1984. V 28. № 5. P 180.
 
*8. Nagornyy V. i., Chibisova N. p. //ufn. 1978. Vol. 19. S. 32.
 
*9. Sherstyuk V. p., Dilung I. I. In the book: Fundamental bases of the optical of pamya- TI and medium. Kiev: Vishcha shk. 1982. Iss. 13. S. 33.
 
*10. Levi S. m., Suchkova O. m., Suvorin V. V.// the jour. of nauch. and appl. photo- and kinema of tografii. 1984. Vol. 29. № 4. S. 252.
 
*11. Murzinov A. V., Moiseyeva G. V., Stryukova e. g. and other// theses of the report republic of se- of minara "applied holography". Kiev, 1984. S. 49.
 
*12. Usikov A. 4., Babichev A. A., Yegorov a. d., etc.// to conduct. AN OF UKRCSSR - UKRAINIAN SSR. 1977. № 10. S. 47.  
 
  
Kharkov state university im. a. M. of Gor'kiy
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[[Image:LippmannFig4.jpg|center|Image 4. Marks of equidensite on Jupiter image: a – initial imprint of astro negative; б – photos of Lippmann’s image received using interference light filter at different angles of its incline at reflected light; в – the same but at passing light.]]
 +
 
 +
At two-step process there inevitably occur distortion and noise at the first stage of registration. Grain on image 4, б is due to that of material on which the initial negative is registered. Therefore you can get much more information when processing Lippmann’s photos received at direct registration. Low sensitivity of dichromated gelatin plates does not allow direct registration of other astro objects except Sun. Direct registration of Lippmann’s photos is possible in biology. Radiation of ДРШ-250 lamp is enough for receiving images with enlargement 30-100x.
 +
 
 +
Thus Lippmann’s photos received on dichromated gelatin plates using sources of monochromatic light have properties appreciably different from those of usual Lippmann’s photo. It’s related to properties of medium of registration. Period of fixed interference structure depends not only on length of radiation wave but also on its intensity. As a result there is a possibility to unambiguously transform light intensity to color. Simplicity of method of receiving Lippmann’s photos, possibility of using sources of low coherent length and high difraction efficiency offers a wide range of possibilities in practicing this method.
 +
 
 +
In conclusion the author estimates as his pleasant duty to express gratitude to V.P.Sherstyuk, and L.E.Mazur for their important discussions, to V.A.Kaminskaya and L.E.Nikishyna for assistance in leading spectrophotometric measurement and to V.N.Dudinov for his kindly giving us astro negatives.
 +
 
 +
== Literature: ==
 +
 
 +
# Lippmann G.C.R.// Acad. Sci. 1891.V.112. P. 274
 +
# Kostylev G.D. // Letters in Technical Physics magazine 1976. T. 2. Edition 23.P. 1086.
 +
# Kostylev G.D., Ivanenko L.I. // Thesis report. IV All-Union conference “Photometry and its metrological equipment”. M., 1982. P. 119
 +
# Sogokon A.B. // Thesis report. IV All-Union conference “Silverless and other unusual processes”. Chernogolovka, 1984. T. 1. Vol. 2. P. 125.
 +
# Sogokon A.B. // Thesis report. IV All-Union conference “Optical image formation and processing methods”. Kishinev, 1985. T. 1. P. 125.
 +
# Lin L.H. // Appl. Opt. 1969. V. 8. №5. P. 963.
 +
# Sjölinder S. // Photogr. Sci. and Eng. 1984. V. 28. №5. P. 180.
 +
# Nagorniy V.I., Chibisova N.P. // Successes of Physical Sciences. 1978. T. 19. P. 32.
 +
# Sherstyuk V.P., Dilung I.I. in “Fundamentals of optical memory and mediums”. Kiev: High School. 1982. Edition 13. P. 32
 +
# Levi S.M., Suchkova O.M., Suvorin V.V. // Magazine of a scientific and applied photo and cinematography. 1984. T. 29. №4. P. 252
 +
# Murzinov A.V., Moiseeva G.V., Stryukova E.G. and others // Thesis report at republican seminar “Applied holography”. Kiev, 1984. P. 49.
 +
# Usikov A. Y., Babichev A.A., Egorov A.D., and others // USSR Science Academy bulletin. 1977. №10. P. 47.
 +
 
 +
Kharkov State University of Gorkiy 13.12.1985<br>Translated by Borozniak Evgeniy
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[[Category:Lippmann]]

Latest revision as of 21:38, 17 May 2013

Lippmann’s photography on dichromated gelatin plate

Sogonkon' A. B.

This article was transcribed from the text in the file available here.

The research of properties of Lippmann’s images obtained on dichromated gelatin plate shows that image color depends on wavelength of radiation as well as on its intensity. It relates to heterogeneous swelling of gelatin and structural changes of its unirradiated parts at fast dehydration.

Unusual behaviour of Lippmann’s images on dichromated gelatin plate may be used for producing selective mirrors for reflecting graphic information and date registration and image processing.

Introduction

There is [1] a method of obtaining color image based on registration of standing waves in the volume of thick transparent photographic emulsion. Period of registered interference structure is unambiguously related to the length of the wave of radiation influencing the plate. This assures right color rendering of photographed image if disposed to white radiation. This method wasn't widely adopted because of big technical problems.

Development of holography leads to creation of a totally new technique of experiment and new registering mediums. There appeared some announcements that Lippmann’s images have been tried on modern emulsions like ЛОИ-2 [2,3] and on dichromated gelatin [4,5].

The aim of this work is to investigate the behaviour of Lippmann’s images made on dichromated gelatin as well as mechanism of image formation and possibilities of its application on practice.

Method and results of experiment

Lippmann’s method is basic for making dichromated gelatin plates [6]. Holographic plates ПЭ-2 and ЛОИ-2 were placed into acid fixing solution then washed in running water and dried at room temperature. The plates were sensitized right before exposure. For this the plate was placed for 5-15 minutes into 1-5% solution of dichromated ammonium and after its runoff dried by hot air current at temperature 100-150°C. The duration of drying is 3-5 minutes.

Image 1. Scheme of device for contact printing of Lippmann’s images. 1 – light source (laser or mercury lamp), 2 – lens, 3 – negative, 4 - dichromated gelatin plate.

Scheme of device for contact printing of Lippmann’s images is displayed on image 1. Widened laser beam is directed onto registering medium. The radiation passed through reflected from plate glass spreads in reverse and forms a standing wave in the volume of registering medium the amplitude of which depends of negative passing. As the source of radiation lasers ЛПМ-11(442nm) and ЛГИ-21 (337nm) and mercury lamp ДРШ-250 were used. Besides direct projecting printing of enlarged images was realized with help of a usual photographic enlarger.

Processing mode of exposured plates hardly differed from that of dichromated gelatin for obtaining hologram [7].

Images obtained using the foregoing method have a number of interesting qualities. If watching at an image in reflected light (almost natural light rays falling) different parts of the image get different colors according to density of initial negative. The image gets blue color under transparent parts and red color under opaque ones. Half-tints of negative are reproduced by hues from orange to green. From this follows that interference structure period depends on length of radiation wave as well as on its intensity.

A Lippmann’s image if placed on a black sheet of paper and watched at broad angle will be black-and-white. Gelatin remains transparent under transparent parts of the image and gets milkwhite under opaque parts. In this case the image is not reproduced by light absorption but its dispersion that resembles the properties of display on vesicular materials [8].

To investigate the dependence of image color on the exposure within one plate a number of exposures was done by collimated laser beam. There were made also photos of sensitometric wedge image and then spectrums of transmission of the received images measured.

On image 2 there are spectral characteristics of images obtained on ПЭ-2 plates sensitized by 1% ammonium solution at exposure by laser ЛПМ-11 (image 2,a) and ЛГИ-21 (image 2, г). It follows from the analysis of spectrums that spectrum reflection width (image 2, e), length of wave maximum reflection (image 2, в) and density of image (image 2, б, д), change according to exposure amount. It is significant that length of wave maximum reflection at considerable exposure does not correspond to the length of radiation wave of the record. It’s due to increasing period of interference structure at layer processing.

Image 2. Lippmann’s images characteristics: а and г - dependence of image transmission spectrums on exposure amount at recording by radiation of helium-cadmium (442 nm) and nitrogen (337 nm) lasers; б and д – dependence of image density on exposure for the same wave length; в – dependence of image color on exposure logarithm (curve 1 – 442, curve 2 – 337 nm); dependence of half-width of transmission spectrums on exposure (1 – 442, 2 – 337 nm).

Length of wave maximum reflection linearly depends on logarithm of exposure (image 2, в) what gives possibility to write

(1)



where λo - length of wave maximum reflection at high energy of exposure (wave length of saturation), H – energy of exposure, k – coefficient of proportionality which may be interpreted as coefficient of colors contrast.

Image color change evokes change of its density (image 2, б, д). These dependences are similar to characteristics curve of nigrescence of simple registering mediums. Nevertheless photographic width of linear region is much smaller. Dispersion of experimental points is especially considerable in regions of high exposure that can’t be explained by measurement errors. We can suppose that dependence of image transmission in region of saturation has oscillating character as demonstrated for example on image 2, д.

Mechanism of image creation

Preparing plates to sensitizing they should be placed into water for a period of time (about one hour). As a result gelatin gets swelled and long protein molecules swivel in the way to create linear chains. It relates more to molecules on the surface of the layer than those which are deep in as they are less exposed to strength of adjacent molecules. There appears a heterogeneous hardening increasing from the layer surface to substrate. Superficial gelatin molecules forming linear chains can no longer perform work as they took favorable energetic position. Molecules deep in the layer have some amount of potential energy. Their interaction with each other and molecules of gelatin hardener prevents their forming linear chains. This hardening can be defined as value inversely proportional to work performed by molecules when processed in water. The layer is not hardened if molecules realized their potential. The layer is hardened If they didn't realize their potential energy when processed in water. Distribution of potential energy in the thickness of hardened layer may be presented in diagram form as demonstrated on image 3,a.

Let’s consider processes taking place at hardening of exposed layers. Here we consider that photochemical transformations Cr (VI) to Cr (III) is realized according to model described in work [9]. At low exposure energies the number of photographic connections between the molecules created in bulge points is also small. Distribution of potential energy of molecules in hardened layer is demonstrated on image 3,б. At enduring processing in water besides hardening of layer in nodes of standing wave there may occur local gelatin dissolution. In other words hydrated molecules get relatively free changing their structure but can’t leave the layer because of hardenings in bulge. Work [10] and [11] describe that gelatin structure change at processing in water as well as at it’s drying. Therefore when processed by isopropanol change of gelatin structure in nodes and bulges are realized different ways. At considerable loss of water molecules don’t have time to return to initial state so they are forced to create a new molecular netting different from that which is created at simple freezing or slow drying. Gelatin density decreases in bulge points of standing due to growth of layer volume and increases in bulges due to change of structure under influence of formed Cr (III). As a result gelatin loses its elasticity. Increased period of interference structure can also be registered in the layer. Increasing exposure involves increasing of potential energy modulation in swelled layer. Number of isophased surfaces recorded in layer increases (image 3, в,г,д). Width of spectrum reflection and displacement to red region decrease but diffraction efficiency increases.

Performance of black-and-white image can be explained by change of gelatin structure. Unstructured spots cause considerable light dispersion and get milk-white colored.

Discussing results

Unusual properties of Lippmann’s photos made on gelatin plates can be used for producing selective glasses as well as for receiving pseudocolor slides from black-and-white negatives and image processing and registration.

Possibility of using Lippmann’s photos as selective glasses follows directly from image 2. Length of wave reflection and half-width depend on exposure value. At this coefficient of reflection reaches 99% that allows using such glasses in laser resonators, interferometers Fabri-Perot and also as beam dividers in hologram devices.

Image 3. Scheme explaining dependence of interference structure on value of exposure: а - distribution of hardening in swelled non-exposed layer; б, в, г, д – modulation of hardening in swelled layer depending on exposure.

They cost less than interference dielectric glasses. There is also possibility of producing glasses of almost any size as well as distribution of spectrum characteristics within glass plane. Pseudocolor slides received from black-and-white negatives may be used for transmission of graphic information for example schemes, tables, diagrams. Slides can be projected at passing light by simple slider as well as at reflected light by epidiascope. It’s better to give preference to the second variant as color gamma is fuller and image contrast is higher then.

At printing from black-and-white negatives value Hmax and H in equation (1) can be presented as

and

from this follows that change of color of Lippmann’s photo is linearly dependent on negative density.

Last time in increasing frequency is used the idea of complex spacial distribution of different physical values by conventional colors for example at image digital processing [12]. This quality is inherent to Lippmann’s photos taking in consideration their nature. Lippmann’s coloring method has an advantage: such image may further be optically processed. Observing a pseudo-colored image through a light filter with gating line Δλ we can see details of initial image in the interval of densities ΔD.

Details of interest of image may be marked by change of wave length of light filter. Diapason of densities may as well be marked by changing its half-width. If you make a photo of image observed through interference filter on a contrast photographic material you can receive image of lines of same density – equidensite. To illustrate this image of Jupiter was processed. For this the image of astro negative was printed with enlargement on dichromated gelatin plate. Then was made photo of received image through interference light filter with λ=640 nm and Δλ=90Å. Photo of initial image is presented on image 4, a. On image 4, б, в there are series of photos made at different angles of interference light filter incline that is at different λ and Δλ. You can see that even in conditions of incorrectly organized experiment (setting of wave length of light filter is realized by its incline) you can discover more details on received images than on initial negative.

Image 4. Marks of equidensite on Jupiter image: a – initial imprint of astro negative; б – photos of Lippmann’s image received using interference light filter at different angles of its incline at reflected light; в – the same but at passing light.

At two-step process there inevitably occur distortion and noise at the first stage of registration. Grain on image 4, б is due to that of material on which the initial negative is registered. Therefore you can get much more information when processing Lippmann’s photos received at direct registration. Low sensitivity of dichromated gelatin plates does not allow direct registration of other astro objects except Sun. Direct registration of Lippmann’s photos is possible in biology. Radiation of ДРШ-250 lamp is enough for receiving images with enlargement 30-100x.

Thus Lippmann’s photos received on dichromated gelatin plates using sources of monochromatic light have properties appreciably different from those of usual Lippmann’s photo. It’s related to properties of medium of registration. Period of fixed interference structure depends not only on length of radiation wave but also on its intensity. As a result there is a possibility to unambiguously transform light intensity to color. Simplicity of method of receiving Lippmann’s photos, possibility of using sources of low coherent length and high difraction efficiency offers a wide range of possibilities in practicing this method.

In conclusion the author estimates as his pleasant duty to express gratitude to V.P.Sherstyuk, and L.E.Mazur for their important discussions, to V.A.Kaminskaya and L.E.Nikishyna for assistance in leading spectrophotometric measurement and to V.N.Dudinov for his kindly giving us astro negatives.

Literature:

  1. Lippmann G.C.R.// Acad. Sci. 1891.V.112. P. 274
  2. Kostylev G.D. // Letters in Technical Physics magazine 1976. T. 2. Edition 23.P. 1086.
  3. Kostylev G.D., Ivanenko L.I. // Thesis report. IV All-Union conference “Photometry and its metrological equipment”. M., 1982. P. 119
  4. Sogokon A.B. // Thesis report. IV All-Union conference “Silverless and other unusual processes”. Chernogolovka, 1984. T. 1. Vol. 2. P. 125.
  5. Sogokon A.B. // Thesis report. IV All-Union conference “Optical image formation and processing methods”. Kishinev, 1985. T. 1. P. 125.
  6. Lin L.H. // Appl. Opt. 1969. V. 8. №5. P. 963.
  7. Sjölinder S. // Photogr. Sci. and Eng. 1984. V. 28. №5. P. 180.
  8. Nagorniy V.I., Chibisova N.P. // Successes of Physical Sciences. 1978. T. 19. P. 32.
  9. Sherstyuk V.P., Dilung I.I. in “Fundamentals of optical memory and mediums”. Kiev: High School. 1982. Edition 13. P. 32
  10. Levi S.M., Suchkova O.M., Suvorin V.V. // Magazine of a scientific and applied photo and cinematography. 1984. T. 29. №4. P. 252
  11. Murzinov A.V., Moiseeva G.V., Stryukova E.G. and others // Thesis report at republican seminar “Applied holography”. Kiev, 1984. P. 49.
  12. Usikov A. Y., Babichev A.A., Egorov A.D., and others // USSR Science Academy bulletin. 1977. №10. P. 47.

Kharkov State University of Gorkiy 13.12.1985
Translated by Borozniak Evgeniy