SU1564663A1 - Method of representation of information of the same type from phase light panel - Google Patents

Abstract

This invention relates to automation and computing. The aim of the invention is to increase the contrast of the displayed information of the same type. The goal is achieved by the fact that, in a method based on spatial modulation of an optical signal with a phase transparency with the same type of information, Fourier transform of the resulting optical signal into the spatial spectrum of elementary optical signals, changing the initial phase value of the elementary optical signal of zero spatial frequency by a value equal to the sum of a quarter the wavelength of the optical signal and half of the change in optical thickness in the fragment of recording information of the same type, and reverse Fourier transform of the spatial spectrum of elementary optical signals, after changing the phase of the elementary optical signal of zero spatial frequency, determine the phases of the elementary optical signals, except the signal of zero spatial frequency, and change the phases of each of the elementary optical signals, except the signal of zero spatial frequency, by equal to the difference between the phase corresponding to the sum of a quarter of the wavelength of the optical signal and half the change in optical thickness a fragment of a record of the same type of information, and the initial phase of the corresponding elementary optical signal, in addition to the signal of zero spatial frequency. Thus, by changing the initial phase of the elementary optical signals of nonzero spatial frequencies, an increase in the contrast of the displayed information is achieved. 1 il.

Description

The invention relates to the field of automation and computer technology, in particular to methods for displaying information of the same type from phase transparency.

The aim of the invention is to increase the contrast of the displayed information of the same type.

The drawing shows an optical diagram of a device that implements the proposed method for displaying information of the same type from phase transparency.

A device implementing the proposed method comprises a source 1 of quasi-monochromatic radiation.

condenser 2, personnel window 3 with phase transparency 4 ,, lens 5, visualizing aperture 6 and screen 7 i

The diaphragm 6 has a variable optical thickness. In the area of zero diffraction order, it changes abruptly by

1 - L / 4 + D / 2,

(ABOUT

Where

1o

a change in the optical thickness of the imaging diaphragm in the region of determining the zero order of diffraction; - wavelength of a quasimonochromatic radiation source;

And the change in optical thickness in the displayed fragment records the phase of the transparency.

Such a change in the optical thickness of the imaging diaphragm provides a change in the phase of the transmitted optical signal by

/ fl-T / 2 + f / 2,

(2)

where C) is the change in the displayed fragment of the record corresponding to the change in optical thickness D. Outside the region of zero diffraction, the diaphragm has a variable optical thickness corresponding to a change in the phase of the transmitted optical radiation by an amount of about.

When the radiation source is located in the back focus of the condenser, the coordinates of the spatial clock for NX 3r are determined through the spatial coordinates f Ј of the plane of the visualizing diaphragm using the expressions

-M}

x

45

In the plane, the visual of the ragma is formed about the spectrum of elementary bonds, described by Fu transparency

 t (x) -F {t (x)} PK () + f% Q)), (5J

f lens focal length.

The process of restoring the visualization of the L-aided image of the phase transparency can be described using the Fourier optics apparatus. For simplicity, the one-dimensional case of a point-source optical system can be considered.

Complex amplitude coefficient. if the insertion of a banner with a fragment of the -m record is given by the expression

0

t (x) PK (x) + t3 (x-x0), where t3 (x) P (x) exp | lf-l J,

(3)

Pk (k)

Vx)

1 - in the frame window area O - outside the frame window area,

1 - in the area of the fragment of the record. O - outside the area of the fragment of the record

ha - coordinate of the fragment center

records; t (x) - transmittance

transparency, limited personnel window;

t- (x) is the transmittance of the transparency area in the region of the recording fragment with a jump in optical thickness D corresponding to the change in phase tj.

The transmittance t. (X) is conveniently represented as

t (x) | t (x) exp (), (4)

where | tv (x) IH2 (l-cosU) P% (x), 4d f / 2 + 1T / 2.

A spatial spectrum of elementary optical signals is described in the plane of the visualizing diaphragm, described by the Fourier spectrum of the transparency.

Fourier transform operator;

the spatial spectrum of the fragment of the record, defined in turn by the expressions

) - | tc «x) | exp JVC}), Pr () -ftvQQllxp j (),

| EL) (. C),)

t (V, VV,) - fuir & e r TTOtrmr ".T / Ort lv no pr PtaOWWr itrtrT4W-

the spectra of the functions t (x) and P (x), respectively.

Q

t (x)

PV (X),

The spatial spectrum of the transparency is transformed by a visualizing diaphragm with an amplitude transmittance Ј (R) that is within the diaphragm's light diameter,

515646636

corresponding to the maximum (frequency of 3m, described by

diaphragm) space

,, Gehr j (lf / 2 + P / 2) W Uxp,) - exp-j (ft-V (V

about

Whence, taking into account expression (6), it follows that for a recording fragment with a constant change in optical thickness (phase). The transmittance of the visualization diaphragm at nonzero spatial frequencies is completely determined by the phase (J (3x) of the spatial spectrum of the function P (x), defining in accordance with (3) the fragment border of the record

OBOX) -tfyC-O,).

If the function Pv (x) is even (which is true for most types of regular phase recording), then its spatial spectrum is P-Oc) is valid, and the phase L (x) has either zero value T at P (X) L (T , or the value of it Ј for P, Qx) .0. However, regardless of the type of function P c (x), the described imaging aperture converts the spatial spectrum Pa (0 y) into a real function in the interval of spatial frequencies

The same configuration of the fragments when recording the same type of information on the phase transparency ensures that the phase of the elementary optical signals remains unchanged, as a result of which the imaging diaphragm with the transmission specified by expression (7) converts the spatial spectrum of the recording fragments in the same way (regardless of their position in the frame window). Practically, the transmittance (3x) takes the value exp jCf0 in a certain region near the zero value of the spatial frequency, # n of which the relation | )} j.) With the fragmentary character of the record, the fragment size x is much smaller than the frame window size xk, the spatial spectrum RK (X) corresponding to the non-recording frame is concentrated near the optical axis (x 0 0) in a region much smaller than record range

at VK 0

at

at / -5x1 tch

(7)

t.f o,). Therefore, the spatial Yu spectrum t О y), transformed by the imaging diaphragm and equal to

Ј (V-t (V.Ј (V,

five

described by the expression

VI

 ) exp j% + t.Ox) exp (-j2411 xx0) exp jot (},), °

20

which, after conversion with regard to dependencies (6) and (7), takes the form

25 t O,) expjlf0 pk (; x) + ltl () jexp (

x,

(eight)

The layer of free space between the imaging diaphragm and the screen performs the inverse Fourier transform from the spatial spectrum of the elementary optical signals transformed by the imaging diaphragm

t (-x) () $, (9)

where t (x) is the amplitude of the optical

signal in the plane of the screen, wound;

F is the inverse Fourier transform operator. Taking into account relation (8), expression (9) is converted to

t (x) -exp (x / p) + tj (x / p-xe)

where | 5 - increase between optically

conjugate planes of the frame window and screen,

50

) -F ({| (Vl}

For perception of information recorded in the form of single-type fragments (corresponding, for example, to lines or points of the formed image), the contrast of the central image area of these fragments relative to the surrounding background is important. This contrast value is proportional to the ratio of the image illumination in the center of the fragment to the background illumination and is directly determined by the intensity of the optical signal in a flat screen for the coordinate, i.e. the value of j t1 (x 0) | a.

In accordance with relations (3), (8) and (9), the value of t (xa) is determined through the transformed spatial spectrum by integrating it in the interval | frequency conversion

() j (+

/ Vi

t

t (x 0) | t () dVK-exp j (| 0 | l +

+). (P)

From the obtained expression, it follows that the use of a diaphragm with a transmission coefficient corresponding to expression (7) and ensuring the implementation of the proposed method of displaying information allows one to obtain an optical signal of maximum intensity. Indeed, if expression (7) is violated, the elementary optical signals integrated in equation (11) corresponding to the transformed spatial spectrum V Oj) will not have a constant phase If0 for all signals, which will lead to a decrease in the intensity of the signal received

.

Simultaneously with an increase in the signal in the center of the image of a recording fragment, it occurs (in accordance with the energy conservation law) that it decreases to the edge of the fragment, i.e., the actual image of the fragment is narrowed compared to its geometric size, which is an additional positive effect for information display systems.

So, for example, for a fragment of a record with a center at the point xff and boundaries that are given by the function P. (x) rect (x / ux), the ratio of the signal intensity for the central image area of the fragment | t (xj,) l4 to the background intensity domains Jtq, (x) | 1 in accordance with dependencies (6), (11) is given by

(x 0) lV | t; (x1)

J

, t "chg

-coeif) J 1 () 1 d3,

- “m

(12)

where Pv () bx sin (S)) (- ux) A%.

Provided that the border of the visualizing diaphragm coincides with one of the zeros of the function P ,, Ox), i.e. where N 1,2,3, ..., when using the integral function

sine sin U / UdU expression (12)

leads to mind

N-i

0

0

five

five

five

(I, p YY-ln + 1

 (l-costf) Ar 2 21 (-I) Si (7n) i-L n-

(-i) Msi ((13)

At the same time, for the imaging diaphragm with e ((- 0x) 0 (prototype), the corresponding expression has the form

2l) 2D-cos Ј) nl

1G

SiC "N)

(14)

five

0

five

The use of expressions (13), (14) when 1 |) Ti leads to, respectively, the values 16 and K 8.76, i.e. The proposed method of displaying information provides a more than threefold increase in the brightness of the rendered image, or, while maintaining the brightness of the image, it can reduce the power of the radiation source by more than three times.

Claims (1)

Invention Formula A method of mapping single-type information from a phase transparency, based on spatial modulation of an optical signal by a phase transparency with single-type information, Fourier transform of the resulting optical signal to the spatial spectrum of elementary optical signals, changing the initial phase value of the elementary optical signal of zero spatial frequency by a value equal to the sum of a quarter wavelength of the optical signal and half the change in optical thickness in the recording fragment one type information, and the inverse Fourier transform of the spatial -spectrum of elementary optical signals, characterized in that, in order to increase the contrast of displayed information of the same type, after describing the phase of the elementary optical signal of zero spatial frequency, the phases of the elementary optical signals are determined, in addition to the signal of zero spatial frequency, and change the phases of each of the elementary optical signals, except for the zero-frequency frequency signal, by an amount equal to the difference m waiting phase corresponding to the sum of a quarter of the wavelength of the optical signal and half nzme15 1564663. YU the optical thickness in the fragment of recording the same type of information, and the initial phase of the corresponding elementary optical signal, except for the signal of zero spatial frequency.