SU1746355A1 - Method of determination of photographic characteristics of photothermoplastic information medium - Google Patents

Abstract

The essence of the method: a focused laser spot with a Gaussian intensity distribution is projected onto a photothermoplastic carrier, the spot diameter is 40 times greater than the thickness of the thermoplastic carrier layer. The relief image of the registered spot is scanned by an annular light beam with a width equal to twice the thickness of the thermoplastic layer and a diameter discretely varying from a value equal to the diameter of the registered laser spot to a value corresponding to the width of the beam, with a step equal to the width of the ring. 1 hp f-ly.

Description

The invention relates to electrophotography and can be used in scientific and applied photography to determine the photographic characteristics of relief media.

The closest to the invention is a method including the registration of a raster projected on a photothermoplastic carrier in the form of alternating light and dark bands through a stepped illumination wedge, the subsequent reading of the reproduction recorded in the form of a phase relief, the construction of a characteristic curve and the determination of its photographic characteristics from it. This method does not allow to determine the photographic characteristics of the media used

for recording information with a large spatial frequency.

The purpose of the invention is the expansion of technological capabilities by determining the photographic characteristics of the media used for recording information with a high spatial frequency.

The essence of the invention is as follows.

Photographic characteristics of a photothermoplastic information carrier with a thermoplastic layer are determined by registering a test object projected onto a carrier, reading a relief image of a registered, test object, constructing a characteristic curve, and determining photographic sensitivity. As a test object proVI 4 O OE JV SJ

A focused laser spot with a Gaussian intensity distribution with a diameter of 40 times the thickness of the thermoplastic layer is produced, and the reading is performed by scanning the relief image with an annular light beam with a width corresponding to twice the thickness of the layer and a diameter varying discretely from a value equal to the diameter of the registered laser spot. to a value corresponding to the width of the beam, in increments equal to the width of the ring. When determining the photographic characteristics in this way, to simplify and speed up the process, the photographic sensitivity can be determined from the ratio

l

O2

2D2

4P

Max

where Рmax is the radiation power in the center of the beam;

ta is the exposure time;

d is the diameter of the registered laser spot;

D is the diameter of the projected laser spot.

The method is implemented as follows.

A focused laser spot with a Gaussian intensity distribution with a diameter 40 times greater than the thickness of the thermoplastic carrier layer is projected as a test object onto the studied photothermoplastic carrier. The image of the laser spot is recorded by the method of photothermoplastic recording, in which a relief image with a well character of deformation is obtained on the surface of the carrier. The registered laser spot is scanned by an annular light beam with a width close to twice the thickness of the thermoplastic layer, and a diameter discretely varying from a value equal to the diameter of the registered laser spot to a value corresponding to the beam width, in increments of different ring width. Since usually 10 values of the intensity of the scattered light are used to construct the characteristic curve, this value is measured for 10 discrete values of the diameter of the annular light beam, which are used to construct characteristic curves that make it possible to establish photographic characteristics. Having determined the values of the diameters Оm d, an express assessment is made of the maximum value of the sensitivity of the carrier by

SJTD2

4 Pmax

and always d D due to the presence

a certain threshold value of the detected intensity of the laser radiation,

Example. The photographic characteristics of a photothermoplastic carrier, which is a photosensitive 2-μm AzaZez layer successively deposited on a metallized ribbon lavsan basis, and the copolymer imaging layer are determined, are determined.

butyl methacrylate with styrene in the ratio of 1: 1 with a thickness of 1.4 microns.

A laser beam L-79-1 with a wavelength of A 0.63 µm, focused to a diameter of D 60 µm, is scanned with a narrow slit and a PMT 84 photodetector, and the power distribution in the spot P (x) is measured.

Then the laser spot is recorded on an FTP-carrier with an exposure time of T.E. 10 s. The resulting image is scanned with a 3 µm wide circular light beam and ICBM values are measured with a photomultiplier with a pitch of 3 µm. Measuring also the intensity of light in a dark place 1t, get a set of n values 1svlt.

Photographic parameters are determined from the characteristic Ig IgSLT curve (Ig Pi) according to a standard procedure.

Measuring the diameter of the recorded spot d 48 µm, determine the maximum sensitivity

9 48

3.14 - (60) 2 2

60

45

4-3-10

-four

ten

0

five

"1i6 .. j

Thus, using as a test object a focused laser spot with a Gaussian intensity distribution with a diameter 4 times greater than the thickness of the thermoplastic carrier layer and reproducing the recorded laser spot with an annular light beam with the suggested parameters, it simplifies the method of determining the photographic characteristics of the carriers on which information is recorded from the big

spatial frequency, in addition, it is possible to conduct a rapid assessment of the magnitude of the photographic sensitivity of the carrier.

Claims (2)

Claim 1. A method for determining the photographic characteristics of a photothermoplastic information carrier, comprising registering a test object projected on a carrier including a thermoplastic layer, reading a relief image of a registered test object, constructing a characteristic curve, determining the photographic sensitivity, characterized in that expanding technological capabilities by determining the photographic characteristics of the media used for registering ation of information with a high spatial frequency, as the test object projecting a focused laser spot with Gaussian intensity distribution, diameter, forty times the thickness of the thermoplastic 0 the layer and reading are carried out by scanning the relief image with an annular light beam with a width corresponding to twice the thickness of the layer and a diameter discretely varying from a value equal to the diameter of the registered laser spot to a value corresponding to the beam width with a step equal to the ring width. 2. The method according to claim 1, characterized in that, in order to simplify and speed up the process, the photographic sensitivity is determined from the ratio 15 lgO2 9d 2D2 4 Pmax U Pmax is the radiation power at the center of the beam; B is the projection time; d is the diameter of the registered laser spot; D is the diameter of the projected laser spot.