SU1677877A1 - Device for measuring distance between the centers of interference bands of interferogram - Google Patents

Abstract

The invention relates to an image processing technique and can be used in television devices for measuring the distance between the centers of periodic structures, such as interferograms. The aim of the invention is to improve the accuracy of measuring the distance between the centers of the interference strips by turning them. For this, the device contains a television camera 1, a differentiation unit 2, blocks 3 and 4 of comparison, triggers 5 and 19, a block 6 of coincidence, a comparator 7, a generator of 8 stroboscopic pulses, elements 9 and 10, a key 11, a generator of pulses 12, block 13 prohibition, reversible counter 14, memory block 15, D / A converter 16, image rotation block 17, null organ 18, standby multivibrator 20 2 Cp f-ly, 9 silt, 1 tab. iU

Description

The invention relates to image processing devices and may find application in television devices for processing interferograms,

The aim of the invention is to improve the accuracy of measuring the distance between the centers of interference fringes.

Figure 1 shows the structural diagram of the device; figure 2 - timing charts of signals; FIG. 3 is a gate driver circuit; figure 4 is a block diagram of the ban; figure 5 - timing charts of the signals in the prohibition unit, where the FID, XI - lowercase and frame sync pulses; figs, 6a, b and 7a, b are comparative diagrams explaining the formation of the error signal; 8 and 9 are diagrams of signals of the Coarse and Accurate mode.

The device contains (FIG. 1) serially connected television transmission chamber 1, differentiation unit 2, first comparison unit 3, second comparison unit 4, first inputs connected to the output of differentiation unit 2, and outputs respectively with the first and second inputs of the first trigger 5, output which is connected to the first input of the coincidence unit 6, the second input of which is connected to the output of the comparator 7, whose input is connected to the output of the differentiation unit 2, the second inputs of the comparison units 3 and 4 being threshold inputs output stresses.

The shaper 8 gates first and second inputs connected to the second and third output of the television transmitting camera 1, the first output with the first input of the first circuit And 10. The second inputs of elements 9 and 10 through the key 11 is connected to the output of the generator 12.

The output of the first comparison unit 3 is connected to the third inputs of the I / I elements 9 and 10 and to the fourth input of the prohibition unit 13, the Fourth inputs of the elements 9 and 10 are connected to the first and second inputs of the prohibition unit 13. The outputs of the elements 9 and 10 are connected respectively to the first and second inputs of the reversible counter 14 connected by the information outputs through the memory register 15 to the information inputs of the digital-to-analog converter 16, the output of which is connected to the input of the image rotation unit 17 and the zero-body 18.

The zero-organ 18 output connected to the counting input of the second trigger 19, the first. the left input of which is connected to the second input of the key 11, and the second output to the third input of the prohibition unit. The first and second inputs of the latter are connected to the first and second outputs of the gate generator 8 gates, and the fifth input - to the third output of the television transmitting camera 1, and the second output of the television transmitting

camera 1 is connected to the recording resolution input of memory register 15 and through a standby multivibrator 20 to the third input of the reversing counter 14.

The timing diagram of the signals at the characteristic points of the device is shown in the diagrams of FIG. 2. Shaper 8 gates contains a generator of 21 pulses, an inverter 22 and two channels, including the elements of HE 23 and 24, two groups of six

5 binary-decimal counters 25-30 in the first channel and 31-36 - in the second channel. Counters 25-27 and 31-33 count line numbers, and counters 28-30 and 34-36 determine the current position value.

0 gates depending on the line number (figb).

Transfer outputs 9 of the first 25 and second 26 counters of the first channel, as well as the first 31 and second 32 counters of the second

5 channels are connected respectively to the summing inputs +1 of the second 26 and third 27 counters of the first channel and the second 32 and third 33 counters of the second channel. Information outputs 1,2,4,8 first 25,

0 the second 26 and third 27 counters of the first channel, as well as the first 31, second 32 and third 33 counters of the second channel are connected to the corresponding information inputs 1,2,4,8 of the fourth 28, right 39

5 and sixth 30 counters of the first channel and the fourth 34. p 35 and sixth 36 counters of the second channel, respectively. The outputs RO of the first 25 and second 26 and third 27 counters of the first channel and the first 31, second 32 and third 33 counters of the second channel are connected together and are the first input of the gate generator 8. Clock inputs C fourth 28, p 29 and sixth 30 counters of the first channel and fourth

5, 34, 35 and sixth 36 meters of the second channel are connected together and connected to the output of the inverter 22 and to the input of the pulse generator 21, and the RO inputs of these meters are connected to a common wire. Transfer outputs

0 of the sixth counter 30 of the first channel and the output 9 of the sixth counter 36 of the second channel are connected via the corresponding elements NOT 23.24 respectively to the first and second outputs of the driver 8 gates.

5 Outputs Ј 0 of the fourth 28 and fifth 29 counters of the first channel are connected to the corresponding inputs of the fifth 29 and sixth 30 counters, and output 9 of the fourth 34 and five 35 counters of the second channel are connected to the corresponding inputs of the first 1 35

and sixth 36 counters. The inputs +1 of the first counter 25 of the first channel and the first counter 34 of the second channel are connected to the input of the inverter 22 and are the second input of the gate generator 8. Input -1 of the fourth counter 28 of the first channel is connected to the +1 input of the fourth counter of the second channel and the output of the pulse generator 21.

Block 13 prohibition (figure 4) is made of the first and second channels, each of which includes three inverters 37-39, two R-S-flip-flop 40.41, binary counter 42, shaper 43 short pulses, and the element AND NOT 44 The first input of the element IS-NE 44 is connected to the +1 input of the binary counter 42 and is the first input of the prohibition unit 13. The second input element AND-NOT 44 is connected to the input of the first inverter 38, the input RO of the binary counter 42, and the third input is the third input of the prohibition unit 13, the output of the element 44 is connected to the input S of the second RS flip-flop 41. The output of the first inverter 38 is connected to the input S of the first RS flip-flop 40, the input R of which is connected to the output of the third inverter 37, the input of which is the fifth input of the prohibition unit 13, and the output of the first RS-flip-flop 40 connected to the input C of the binary counter 42. Inputs 1, 2, 4 , 8 of the latter are the inputs of zero potential, the output of the binary counter 42 through the second inverter 39 is connected to the input R of the second R-S flip-flop 41, the output of which is connected to the input of the short-pulse shaper 43. Its output is the second output of block 13.

The output of the similar short pulse generator of the second channel is the first output of the prohibition block 13, the second and third inputs of the second channel element 44 are connected respectively to the second and third inputs of the same AND channel of the first channel. The input of the third inverter 37 of the second channel is connected to the input of a similar third inverter of the first channel, and the first input of the analogous AND element of the first channel is the second input of the prohibition unit 13.

The device works as follows.

The image of interference fringes is projected into the plane of the photocathode of the transmitting tube of the television camera 1. From the output of the television camera 1, the video signal is separated from the DC component in the differentiation unit 2 and is fed to the inputs of the first and second comparison blocks 3 and 4, where it is compared with

threshold voltages t-Un and -Un of opposite polarities.

The pulses from the outputs of blocks 3 and 4 of the comparison are fed to the inputs of the first trigger 5 5, forming at its output a pulse proportional to the band width. In addition, from the output of the differentiation unit 2, the signal is fed to the input of the comparator 7 at the output of which a pulse is generated, the front

10 which front corresponds to the transition of a differentiated video signal through the zero level. Thus, at the output of the coincidence unit 6, a signal is generated that carries the position information

5 of the center of the interference band.

The operation of the device proceeds in two modes: Coarse and Accurate. In the Coarse mode and the Start signal, the first output of the second trigger 19 is set to low.

0, the potential at the second output is high (Fig. 2d, d), while the key 11 is closed, and a high potential is applied to the third input of the prohibition unit 13. The operation of the prohibition unit 13 is synchronized by the horizontal sync pulses arriving at the fifth input, and gates are supplied to the first and second inputs (Fig. 2b, c). At the moment of coincidence of the video signal pulses (Fig. 2a) with the corresponding strobe, a counting pulse is formed at the output of the prohibition unit 13 (Fig. 2k). During one half-frame from each interference band, by coincidence with the corresponding strobe, one counting pulse is formed. With a significant clone of interference fringes, the number of counting pulses on the first and second outputs of block 13 of the prohibition is different. Counting pulses through the first 9 and second 10 schemes And arrive at the inputs-reversing

0 of the counter 14, at the output of which a number is set in the binary code corresponding to the difference of the counting pulses. . Resetting counter 14 is reset by a short pulse generated by a waiting multivibrator 20 triggered by a falling front XI. The binary code is stored in the memory register from frame to frame, while the recording of information from the output of the reversing counter 14 is performed by the XI.

From the output of the digital-to-analog converter 16, a constant voltage of one or another polarity, depending on the slope of the interference fringes, goes to

5 input block 17 rotate the image. The rotation of the image is processed until the number of counting pulses at the inputs of the reversing counter 14 is comparable. At this point in time, the zero voltage at the output of the digital-analogue

Converter 16 triggers a zero-body 18, at the output of which a pulse is generated, which arrives at the first input (counting) of the second trigger 19. A low potential is applied to the third input of the inhibiting unit 13 and a high potential to the second input of the key 11.

The device enters the Exactly mode. Clock pulses (Fig. 2g) from the output of the generator 12 through the key 11 are fed to the second inputs of the elements 9 and 10. At the outputs of these elements, a burst of pulses are formed (Fig. 2i, k), the length of which corresponds to the overlap of the video signal with gates di and d2 on the corresponding lines. In Figure 2, it can be seen that for the case under consideration the video signal overlap with the gates di occurs on four lines 1-4, and with the gates d2 on two lines i-2, 1-1. The dissipation signal at the output of the D / A converter 16 through the image rotation block 17 turns the image until the number of pulses in the bursts coincides. In this case, the image of the bands is formed in a position perpendicular to the horizontal scanning, and the pulse from the output of the null organ 18 transfers the second trigger 19 to the Coarse mode to prepare the device for the next work cycle.

The shaper 8 gates (fig.Z) works as follows. After zeroing the upper row of counters of both channels with a pulse of XSI, the binary codes of the current line number arrive at information inputs 1,2,4,8 of the lower row of counters of both channels, respectively. In this case, the lower row of counters of the first channel works for subtraction, therefore the delay of the skew pulse, i.e. strobe di at the output of the sixth counter 30 of the first channel grows in proportion to the line number (fig.2b). The bottom row of counters of the second channel works on addition, therefore the delay d2 of the strobe at the output of the sixth counter 36 of the second channel decreases in proportion to the line number (fig. 2b).

The pulse generator 21 is phased by the FID pulses from the output of the inverter 22. The pulse repetition rate from the output of the pulse generator 21 is proportional to n2 (where n is the number of useful image lines).

The operation of prohibition block 13 will be considered for the second channel, to the input 1 of which the strobe di is received. Gates di are fed to the second channel and vice versa in order to provide the same sign of the difference of the counting pulses at the outputs of the elements And 9 and 10 in the coarse mode with respect to the mode Precisely. In the initial position, a high potential is set at the output of the second R-S flip-flop 41 (FIG. Be). At the moment of coincidence of the strobe di and the video signal at the output of the AND-HE44 circuit on the inputs S of the second trigger

R-S 41 is given a negative polarity pulse, forming a negative differential at its output. A short pulse is formed at the output of the short pulse shaper 43

0 polarity (fig.5zh, and and fig.8).

Further moments of coincidence of the strobe di and the video signal do not trigger the binary counter 42, since it is reset by the video signal at the RO input.

5 When a video signal is twice or more lost in the strobe zone (Fig. 56), a high potential occurs at the output of the first RS flip-flop 40 (Fig. Bg), which in the absence of pulses at the +1 input unlocks the binary counter 42, which reads up to two input +1 and a positive polarity pulse from output 2 through the second inverter 39 sets the second RS flip-flop 41 to the initial state

5 (fig.5zh). The first video signal pulse from the next interference band (Fig. 56), which coincided with the strobe di (Fig. 5b), translates the second R-S flip-flop 41 into another state, forming the next counting

0 impulse (fig.5zh).

The first channel di works in the same way. On Fig and 9 are additional diagrams characterizing the operation of the device in the modes of Coarse and Precise.

5 Structurally, the device is made in the form of optical-mechanical and electronic components. The optical-mechanical assembly consists of an image rotation block 17, made on the basis of electromechanical

0 drive and optical system, including a Dove prism.

The use of the invention improves the accuracy of measuring the distance between the centers of interference fringes.

5 by taking into account their inclination relative to the horizontal direction of the television transmitting camera 1. Data on improving the measurement accuracy can be obtained by comparing Figs 6 and 7. These fig0 pax schematically show an interference band of width o located at an inclination angle d relative to the rectangle, formed by a raster television tube with sides having

five

(2) g. 7-1 W / and

3: 4 aspect ratio. FIG.

(2) Ida - projections of the intersection of the borders of the strip

1 with the lines of strobes di and d2, and e is the angle

(2) 6-1 IJ / between the strobe lines. In FIG. The projection of the intersection of the band I0 with the line of sight, and for this case Ј 0. As can be seen from FIG. 6-1, the relative value

$

Ic

(d) SC (d) Fi ((5) and

A, Fi (5) -Fi (0) Fi (5) -1.

The graph of the function Fi (5) is shown in Fig.6-2. Similarly, you can get the function

& $.

Ic

Ic

 SC (e3-e) -SC ((5 + 6Ј) F2 (5) and

A F2 ((5) -F2 (0),

The graph of the function F2 (d) is shown in FIG. 7-2.

The calculated values of AI and are given in the table at e / 2 of 36.87 °.

The table shows that with the same control signal, for example, D 6 relative units, the accuracy of the interference band setting is different:

d 0,02 ° with D 6,54 rel.

d 2.0 ° with AI 6,1 rel.

Claims (3)

1. A device for measuring the distance between the centers of interference fringes, interferograms, containing a transmitting television camera, the first input of which is connected to the input of a differentiation unit, the output of which is connected to the first inputs of the first, second and third comparison units, the second inputs of which are threshold inputs and the outputs are connected respectively to the first and second inputs of the first trigger and the second input of the match block, the output of the first trigger is connected to the first input of the match block, the output of the cat The device is output, characterized in that, in order to improve the measurement accuracy by changing the position of the interferogram, an interferogram rotation unit optically coupled to a television camera, a pulse generator, a key, first and second elements And, a reversible counter, a memory register are introduced multivibrator waiting, digital-to-tax converter, zero-body, second trigger, prohibit unit, gate driver, the first and second inputs of which are connected respectively to the second and third outputs of the television cameras The first outputs of the gate generator are connected to the first inputs of the first And element and the prohibition block, and the second output to the first input of the second And element and the second input of the prohibition block, the second inputs of the And elements through the key is connected to the output of the pulse generator, the third inputs of the AND elements are connected to the output of the first block compared to 10, and the fourth inputs of the AND elements are respectively with the first and second outputs of the prohibition block, the outputs of the first and second And elements are connected to responsibly to the first and second inputs of the reversible 5 of the counter, the output of which is connected via serially connected memory register and digital-analogue converter connected to the inputs of the interferogram image rotation unit and the zero-organ, the output of which is connected to the first input of the second trigger, the first output of which is connected to the second key input, and the second output - with the third input of the prohibition unit, the fourth input of which is connected to the output of the first 5 of the comparison unit, and the fifth with the third output of the transmitting television camera, with the second input of the second trigger being the input of the trigger signal, and the second output of the television camera gear 0 is connected to the memory register write enable input and via a standby multivibrator with the third input of the reversible counter. 2. The device pop. 1, which differs 5 in that the inhibit unit consists of the first and second channels, each of which includes the first, second and third inverters, the first and second RS-flip-flops, a binary counter, a shaper of short pulses and an element, in each channel, the first input of the And element is connected to the +1 input of the binary counter and is the first input of the inhibiting block, the second input is connected to the input of the first inverter and the RQ-BXO5 home of the binary counter, and the third input is the third input of the inhibiting block, the output of the element And connected to the S-input w cerned R-S-flip-flop, and a first inverter output is connected to the input of the first S-R-S-flip-flop, 0 The R-input of which is connected to the output of the third inverter, the input of which is the fifth input of the inhibit unit, and the output of the first R-S flip-flop is connected to the C-input of the binary counter, with the inputs 1, 2, 4, 8 5 of the latter are the inputs of zero potential, the output of the binary counter through  the second inverter is connected to the R-input of the second R-S flip-flop. the output of which is connected to the input of the driver short pulses, and the output of the driver the short pulses of the second channel is the second output of the inhibit unit; the output of the short pulse generator of the first channel is the first output of the inhibit block; the second and third inputs of the second channel element And are connected to the second and third inputs of the first channel element, respectively; the third inverter input of the second channel is connected with the input of the third inverter of the first channel, and the first input of the AND element of the first channel is the second input of the inhibiting unit, 3. Device pop. 1, characterized in that the gate driver contains a pulse generator, an inverter and two channels, each of which includes an HE element and six binary-decimal counters, with in each channel the outputs 9 of the first and second counters are connected to inputs +1 of the second and third counters, respectively, outputs 1, 2, 4, 8 of the first two and three counters are connected to inputs 1, 2, 4, 8 of the fourth, fifth and sixth counters, respectively; Ro inputs of the first, second and third counters are connected among themselves and are the first in Odom gate driver, C-inputs counters fourth, The fifth and sixth are interconnected, and their Ro-inputs are connected to a common wire, the Ro-inputs of the first, second and third counters are connected to the same inputs of similar counters of the second channel, the pins 0 of the fourth and fifth counters of the first channel are connected respectively to the inputs -1 of the fifth and sixth counter, and the output SO of the sixth counter of the first channel is NOT connected to the first output of the gate generator through inputs, the + G inputs of the first counters of both channels are connected and are the second input of the gate generator, -1 input The first counter of the first channel is connected to the +1 input of the fourth counter of the second channel and the output of the pulse generator, the input of which is connected to the C inputs of the fourth, fifth and sixth counters of both channels and the output of the inverter whose input is connected to the second input of the gate generator, outputs 9 of the fourth and fifth counters of the channel are connected to the inputs of the +1 fifth and sixth counters of this channel, respectively, and the output E of the sixth channel is NOT connected to the second output of the gate driver. but "rough exactly FI.2 R 5 4I 2 GL / fieL a 5 V d e g FIG. five # M0na / 7C / 2 Sassy c / f I F 1 to" Fit 6) FIG. b Ј ± С Fiz7 a) 8th beginning I one NIN U4. i I I .1 II 11 I III m I I g Am illllijnill I I 11. llfltllitl Illlil pip lilt i a) on the beginning AtTirFig. AT 5) 8 end iii  shchi1 iiiiiii shchi Illi illllli Ulllli d) at the end 9