RU1770980C - Method of optically recording and reproducing information on luminescent photographic material - Google Patents

Abstract

Field of use: optical recording, storage and reproduction of information. SUMMARY OF THE INVENTION: During recording, luminescent photographic material is exposed to active linearly polarized optical radiation in accordance with the information signal. When reproducing information, the material is irradiated with unpolarized radiation of a different spectral composition, and the reproduced optical information is modulated. polarization signal. From the photoelectric signal, the detected signal is isolated periodically. information signal. 1 ill.

Description

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WITH

The invention relates to methods for optical recording and reproduction of information and can be used to record both optical images and electrical signals, for example, sound, on uninterrupted photographic materials.

A known method for optical recording and reproduction of information based on the use, in particular, of photochromic materials. These materials undergo photochemical transformations under the influence of optical radiation, resulting in changes in the absorption spectrum that persist after the exposure radiation is turned off. The information thus recorded is reproduced in an adsorption manner by visually or electronically measuring the spatial modulation of the read radiation intensity. The practical widespread use of this method is hindered by the low photosensitivity of materials based on photochromic reactions.

Closest to the technical nature is a method of increasing the photosensitivity of luminescent photographic materials by reducing the effect of photon luminescence in the reproduction step. It is based on the possible difference in decay time.

luminescence tlum substance which

forms an image and tftSK impurities forming a background. The method consists in initially exposing the photographic material to information-activating radiation, and then irradiating it uniformly with short pulsed radiation of a duration of about ten different spectral composition absorbed by the products of the photochemical reaction that occur during the initial exposure,

vi

Vj

OU 00 O

the image reproduced in the light of luminescence is delayed by an amount

t $ yum after the end of the exciting pulse. This method allows you to reduce the effect of background luminescence, but it is difficult because it requires the use of pulsed sources of readout radiation and electrical synchronization circuits and applies only to luminescent photographic materials in which the condition

t / jiow t $ um for the duration of the luminescence glow,

The purpose of the invention is to increase the light sensitivity of the overall luminescent photographic material and to improve the reliability of the reproduced information.

The goal is achieved in that when recording information, the material is exposed to linearly polarized radiation. During playback, the reproduced optical information signal is filtered by polarization, and a periodic information signal is extracted from the photoelectrically recorded signal. The property of optical anisotropy is known to be characteristic of most substances and media of both natural and artificial origin. Individual individual molecules are anisotropic, i.e., they have their own absorption and radiation oscillators, which can most often be considered linear. The probability of Ј light absorption by such molecules is proportional to the square of the product

Ј-1E 21 / g 2co520,

(D

where E is the electric field vector of the exciting light;

/ T is the vector of the dipole moment of the transition upon absorption;

E is the angle between them.

The luminescence of the molecules is also anisotropic. This is the basis for the method of recording and reproducing optical information on luminescent materials, which is as follows.

A layer of luminescent photographic material isotropic in the initial state with photosensitive molecules randomly (isotropically) distributed along the orientation in it (A)

Sah (x, y) Sau (x, y) Ca. (2) and luminescent impurity molecules

Sprh (x, y) Spru (x, y) Spr (3) is initially exposed to linearly polarized light with intensity ° x (x, y), which carries information about the registered object.

Here sah.u; Spr, y are the volume concentrations of molecules oriented along the X, Y axes of the orthogonal coordinate system lying in the plane of the luminescent material and it is assumed that the polarization vector of the recording radiation incident along the Z axis is parallel to the X axis.

Moreover, in accordance with (1), only those molecules A are predominantly excited and enter into the photochemical reaction

the absorption oscillator of which has a direction close to the direction of the vector of the electric field of the recording radiation.

The luminescent molecules B formed as a result of a photochemical reaction also have a preferred orientation:

Ca kax 1 ° 6x (x, y) (4) 25 Ca (x, y) Ca kay l ° 6x (x, y) (5)

TSW (x, y)

where kax, y are coefficients depending on anisotropic properties (absorption probabilities (1) and photochemical quantum yield

reactions of the starting molecules (A).

Thus, the entire set of luminescent luminescent molecules that are located in the exposed layer of a luminescent material can be represented as consisting of two parts: completely randomly (in orientation) impurity molecules located and mainly oriented (in accordance with the orientation of the polarization vector) recording radiation) of the photoproduct molecules (B) carrying information about the recorded object.

While the concentration of the first is constant over the surface of the layer and is independent

of the radiation energy during recording, the concentration of the latter is uniquely associated with it. The higher the localized radiation energy on the surface during recording, the higher the concentration of molecules (B) and, therefore, the

more local orientational anisotropy of the layer during reproduction.

At the stage of reproducing the recorded information, the luminescent photographic material is exposed

unpolarized light absorbed by molecules (B) (and impurities), as a result of which their luminescence is excited. The light emitted by the exposed photographic material is partially polarized and can be represented as a collection of unpolarized radiation of a randomly oriented ensemble of luminescent impurity molecules

1pr (x, yNpru (x.u) 5 1pr cr

and partially polarized luminescence of B. molecules forming an image

, in r-a io6

Г3х (х.у) квхСаГх (х, у) 1 account (8) lnpy (x, y) kByCalo6x (xiy) tC4MT (9)

where kB, knp, are constants characterizing the luminescent ability of molecules (B) and impurities, and 1Count is the intensity of the set source, which causes the luminescence of the material and

kx, y kax.ykB

The total luminosity of the components polarized in the direction of the X and Y axes at some point of the recorded image (x, y), respectively, will be:

Ix (x, y) knp Ref I

| Counts

about/.

+

kx Ca lx °° (x, y) i

SMITH

gchl L l |

ly (x.y) knP C pr . about / ...

+ ky Ca 1 обх (х, у) 1

and their difference is equal

1х (х, уШх. 1обх (х.у) r T {kx-ky) k 1обх (х.у) (12)

where k Ca, (kx-ky) iC4MT const.

Thus, information about the recorded image in this method is represented as the difference in the intensities of the luminescence of the components, polarized in the direction of the X and Y axes, independent of the background intensity.

To measure it, partially polarized luminescent radiation from the exposed photographic material is transmitted through a polarizer rotating with a circular frequency O). The light intensity at the output of a given polarizer at each time t is determined by the expression:

I (x, y, t) lx (x, y) cos2 an + ly (x, y) sin2 an. - S.U) + y (h.u) 2

+ M.u) -AЈm1-. cos (2ol)

5const + JLlC2 2 "l., Xoe (Xiy) (13)

The first term, which is the sum of the useful weak signal and strong background, does not depend on time, while the second,

10 carries only information about the object recorded on the material, is modeled with a frequency of –2ш, i.e. this filters the information signal by polarization.

15 Next, the light signals are converted into electrical signals using a photocell and, using traditional radioelectric methods, the signal is extracted from a photoelectrically registered signal

20, a variable component of the information signal, which may be 102 to 10 times smaller in magnitude than the constant component.

Example. The implementation of the method of optically recording and reproducing information is provided by a device, one embodiment of which is shown schematically in the drawing. The principle of its operation is based on the method of rotating

30 floor riser. The device contains luminescent photographic material 1, which is affected by the radiation of the recording source 2, the wavelength of which lies in the sensitivity region of the photographic material 1.

35 and radiation from a reproducing source 3, the radiation wavelength of which lies in the luminescence excitation region of the photoproduct occurring at the recording stage. Mirror 4 serves to align

40 beams of recording and reproducing radiation on the surface of the material 1, and the filter 5 at the input of the photodetector 6 ensures that only the reproducing radiation enters the photodetector. Module 7

45 controls the spatial distribution of the intensity of the recording radiation in accordance with the storage information, Polarizer 8 serves to obtain a linear polarized recording radiation 50. The polarizer 9 is mounted in front of the photodetector 6 and rotates with the help of the device 10 with a frequency w. The electrical signal recorded from the photodetector 6, through the frequency

55 selective filter 11 to the recording device 12.

When recording information, obtaining a recording source 2, passing through a modulator 7 and a polarizer 8, acts

on photographic material 1, creating in it a partially oriented ensemble of molecules (B) capable of luminescing spatially modulated by concentration. When reproducing recorded information, the unpolarized radiation of the reading source 3 passes through the same section of material 1, causing partially polarized luminescence, the anisotropy of which is modulated in accordance with the recorded information. Due to the rotation of the polarizer 9, a pulsed light stream is incident on photocell 6, causing a pulsating photocurrent in its circuit, from which, using a partially selective filter 11, a variable component with a frequency of 2ft) is modulated, in accordance with the information recorded on photo material 1. The information thus extracted is recorded in the device 12, which can be a film, a computer, a cathode ray tube, etc.

In the experiment, photochromic material (PCM) was used as a luminescent photographic material, which is a solid 5% (by weight) solution of 1,3,3-trimethyl-6-8-dinitropyro (indoline-2,2- ( 2H-1) -benzopyran in polymethylmethacrylate, deposited on a glass substrate with a thickness of 15 μm. Such a material, isotropic in the initial state, was transparent in the visible region of the spectrum and intensively absorbed radiation with A 390 nm, stained violet with a maximum

absorbance at A max 545 nm. The colored form of the PCM was luminescent in red (Ataka 580 nm) under the action of visible radiation.

This PCM was used for optical recording and reproduction of information according to both absorption and luminescent readout principles (see table).

The radiation source for recording and reproduction was a DRSh-250 mercury lamp. In this case, UV C and BC-7 filters (A act1 365 nm) with a polarizer — the Glan prism — were used for recording, and OS-11 + PS-7 + SZS-21 (Aiz 546nm) filters were used during playback. The reproduced image was observed either through the same filters (for the absorption method) or through an interference filter with Alu73G585 ± 10 nm (for the luminescent prototype method and the claimed method).

Before recording the information, the PCM sample was uniformly exposed to unpolarized UV radiation for 2 seconds, which was equivalent to the presence of luminescent impurities in the PCM, in spectral (Alum) and temporal (gLum) characteristics, identical to the characteristics of the molecules that form the image. In this case, the pulse

The luminescent method (protrtype) did not have an advantage over the traditional luminescent reading method.

The table shows the experimental results for various recording methods and

reading

where is the time for preliminary uniform illumination of the PCM with unpolarized UV radiation to form background absorption and luminescence (impurity);

tM33Kc exposure time of the PCM with recording radiation, necessary to obtain contrast in the image

background, from the intensity of the reading or reproducing radiation in the background and image regions, respectively, with absorption or luminescent reproducing methods,

The table shows that the proposed method can significantly reduce the time of recording information (increase photosensitivity) in comparison with the known methods even when using the same photographic material.

The method allows recording optical signals (images), the intensity of which can be not only comparable, but also lower than the intensity of the background radiation i.e. to improve the accuracy of information reproduction, which, in turn, allows to reduce the power consumption of the recording source, that is, to increase the effective photosensitivity of real luminescent photographic material and (or) to reduce the requirements for the selection and cleaning of the substrate used in their manufacture, film-forming components, photosensitive and other substances in order to reduce the level of luminescent when reading the background.

Claims (1)

SUMMARY OF THE INVENTION A method for optical recording and reproduction of information on luminescent photographic material, in which the recording process exposes the material with actinic optical radiation in accordance with the information signal, and when reproducing the information, the exposed material is irradiated with unpolarized optical radiation of a different spectral composition and photoelectricly record the optical signal reproduced from the material, distinguish and so that, in order to increase the photosensitivity of the luminescent photographic material and improve the accuracy of information reproduction, when recording information, the material is exposed to linearly polarized radiation, during reproduction, the reproduced optical information signal is filtered for polarization, and extracted from the photoelectrically recorded signal a periodic information signal.