CN104536469A - Optical coherence tomography optical probe automatic tracking and positioning control system - Google Patents

Abstract

An optical probe automatic tracking and positioning control system for optical coherence tomography for mural detection, including an optical probe clamping device and an infrared optical probe, and four quadrants around the infrared optical probe are sequentially provided with A-position photodetectors , B position photodetector, C position photodetector and D position photodetector, described infrared optical probe is clamped by described optical probe clamping device, and described optical probe clamping device is provided with pitching rotation Motor, horizontal rotation motor, longitudinal displacement stepper motor, lateral displacement stepper motor and programmable controller. The invention can ensure that the optical probe is perpendicular to the surface of the mural and the distance from the surface of the mural is equal to a fixed value, so that the image tested on the mural is the clearest and most stable.

Description

Optical probe automatic tracking and positioning control system for optical coherence tomography

technical field

The invention belongs to a photoelectric automatic control system, in particular to an optical probe automatic tracking and positioning control system for optical coherence tomography for mural detection.

Background technique

In 1991, David Huang et al. of MIT applied the principle of Michelson interference and confocal microscopy to biomedical imaging, and proposed Optical Coherence Tomography (Optical Coherence Tomography). Optical coherence tomography combines advanced optical technology and modern computer image processing technology, and develops into a new tomographic imaging technology. It adopts low-coherence interferometry technology to obtain the internal microstructure information of the tissue, and its imaging depth reaches several millimeters, which provides a very effective technical means for people to analyze the internal microstructure, shape and texture of the object tissue. Optical coherence tomography has the following main advantages in material detection: high resolution, usually up to about 10 microns, can observe more sample details, fast imaging speed of the system, in addition, its non-contact detection method makes its application It is simpler and safer, and its portability makes it more convenient for researchers to carry.

Optical coherence tomography was originally widely used in medical diagnosis and treatment, such as human eyes, human skin tissue imaging, and early detection of dental caries. In recent years, with the continuous development of OCT technology, its application has been extended to many basic research fields such as material science and thin film technology.

As an advanced non-destructive testing method, in recent years, people have carried out research on the application of optical coherence tomography in archaeology and cultural relics protection, and have made great progress. Due to the use of non-contact technology, this technology can On-site in-situ real-time detection of cultural relics is realized. The research results show that this imaging technology has great development prospects in the fields of cultural relics protection and archaeology. Although optical tomography technology has the characteristics of high resolution, fast imaging speed and non-destructive safety, it also has technical limitations, that is, due to the limited field of view of the imaging system, its one-time imaging size is generally several centimeters How to achieve fast imaging of such a large size of murals is the key to the application of optical tomography in the protection of cultural relics.

Since the automatic imaging range of the optical tomography system is on the order of centimeters each time, the imaging of large-scale murals by the OCT system must be scanned multiple times in a row in the horizontal and vertical directions to complete the large-area imaging of the murals. When the surface of the object being scanned and imaged is undulating, it will cause the optical probe to be unable to align vertically with the object to be measured and the imaging distance of the object will change, which will affect the focusing function of the system, resulting in a decrease in the signal-to-noise ratio of the system imaging and a decrease in imaging quality. It is very important to design an optical probe automatic tracking and positioning control system for the optical coherence tomography system used in mural detection to improve the imaging quality and system stability of the detection system.

Contents of the invention

The present invention aims to overcome the above-mentioned technical deficiencies, and provides an optical probe automatic tracking and positioning control system for optical coherence tomography for mural detection, so as to improve the imaging quality of the optical coherence tomography system.

Technical solution of the present invention is as follows:

An optical probe automatic tracking and positioning control system for optical coherence tomography for mural detection, including an optical probe clamping device and an infrared optical probe, characterized in that: the four quadrants around the infrared optical probe are sequentially set A Position photodetector, B position photodetector, C position photodetector and D position photodetector, the infrared optical probe is clamped by the optical probe clamping device, and the optical probe clamping device It is equipped with a pitching rotation motor, a horizontal rotation motor, a stepping motor for longitudinal displacement, a stepping motor for lateral displacement and a programmable controller, and the input end of the programmable controller is connected with the photodetector at position A and the photodetector at position B , the C position photodetector is connected to the output end of the D position photodetector, and the output end of the programmable controller is connected to the pitch direction rotation motor, the horizontal direction rotation motor, the longitudinal displacement moving stepper motor, the lateral displacement The control terminal of the mobile stepper motor is connected.

When the system is working, the four photoelectric position detectors detect the position parameters in real time, and transmit the measured data to the programmable controller, calculate the number of running steps and the execution distance of the corresponding execution motor, and the controller sends commands to the corresponding execution The motor, the corresponding executive motor rotates or moves accordingly, driving the infrared optical probe to rotate or feed longitudinally until the infrared optical probe is perpendicular to the mural to be measured, and the displacement motor drives the probe to move to ensure that the probe is perpendicular to the sample surface Moreover, the distance from the sample surface is equal to a fixed value to ensure that the test image at this time is the best clear and stable.

Technical effect of the present invention:

The outstanding feature of the present invention is that the structure is simple, the original optical system is not changed, only a position detector is added around the infrared probe, and a servo motor is installed on the probe clamping mechanism to automatically adjust the alignment direction of the probe to the mural surface and The detection distance improves the imaging quality of the system and facilitates fast real-time imaging.

Description of drawings

FIG. 1 is a schematic structural diagram of an optical probe for existing optical coherence tomography;

Fig. 2 is a schematic structural diagram of an optical probe automatic tracking and positioning control system for optical coherence tomography of the present invention.

Fig. 3 is a schematic diagram of four position detectors of the infrared optical probe of the optical coherence tomography system of the present invention.

Fig. 4 is a schematic diagram of the front view of the infrared optical probe position detector of the optical coherence tomography system of the present invention.

Fig. 5 is a schematic diagram of the location detection algorithm and principle of the present invention.

Fig. 6 is a schematic diagram of the principle and working process of the automatic tracking and positioning of the optical probe of the present invention.

In the picture:

1 - Infrared Optical Probe

2 - The surface of the object to be measured

3-4 position detectors

4 - Horizontal rotation motor

5 - Tilting rotation motor

6 - Longitudinal displacement motor

7 - Lateral displacement motor

8 - Probe clamping mechanism

9 - Position detector A

10 - Position detector B

11 - Position detector C

12 - Position detector D

13 - light entrance hole

14 - probe initial position 1

15 - Probe rotation position 2

16 - Probe lateral movement position 3

17 - Probe longitudinal movement position 4

18 - Lateral movement direction

19 - Vertical movement direction

20 - The initial position of the normal line of the probe

21 - Detection position Probe normal position

22 - Probe surface tangent

23 - Probe rotation angle θ

24 linear movement displacement ΔLy

25 - The difference between the detection distances of position detectors A and C Δl _AC

26 - Distance between position detector A and detection surface L _A

27 - Distance between the position detector C and the detection surface L _C

28 The difference between the detection distances of position detectors B and D Δl _BD

29 - Distance between position detector B and detection surface L _B

30 - Distance between position detector D and detection surface L _D

Detailed ways

The present invention will be further described below in conjunction with accompanying drawings, but the protection scope of the present invention should not be limited thereby.

Please refer to FIG. 2 . FIG. 2 is a schematic structural diagram of an optical probe automatic tracking and positioning control system for optical coherence tomography of the present invention. Referring to Fig. 3 and Fig. 4, it can be seen from the figures that the optical probe automatic tracking and positioning control system for optical coherence tomography of mural detection in the present invention includes an optical probe clamping device 8 and an infrared optical probe 1. The four quadrants around the optical probe 1 are successively provided with A position photodetector 9, B position photodetector 10, C position photodetector 11 and D position photodetector 12, and the infrared optical probe 1 consists of the optical Probe clamping device 8 is clamped, and described optical probe clamping device 8 is provided with pitching rotation motor 5, horizontal rotation motor 4, longitudinal displacement stepper motor 6, lateral displacement stepper motor 7 and programmable controller (Fig. Not shown in), the input end of this programmable controller is connected with the output end of described A position photodetector 9, B position photodetector 10, C position photodetector 11 and D position photodetector 12, so The output end of the programmable controller described above is connected with the control ends of the pitching direction rotating motor 5, the horizontal direction rotating motor 4, the longitudinal displacement stepping motor 6, and the lateral displacement moving stepping motor 7.

According to the data collected by the position detector, the system calculates the position offset between the probe and the standard test position, and then feeds the offset back to the motor drive unit of the probe clamping mechanism, through the linear displacement motor, horizontal rotation motor and pitch motor Rotate so that the distance between the probe position and the surface of the sample to be measured reaches a specified value, and the axis of the probe is perpendicular to the tangent plane of the measured surface.

Principle of the present invention is as follows:

A position photodetector 9, B position photodetector 10, C position photodetector 11 and D position photodetector 12 are set around the infrared probe of the original frequency domain OCT system. These four position detectors are used to detect The distance between the four corners of the infrared probe and the four positions on the surface of the sample to be measured is two detectors in the diagonal direction as a group. According to geometrical principles, if two points on the diagonal of a plane square are at the same distance from the circular surface, the normal of the plane square is perpendicular to the corresponding surface tangent. In the system, the corresponding infrared probe axis is perpendicular to the measured surface. As shown in Figure 5. Take a pair of A-position photodetector 9 and C-position photodetector 11 on the diagonal as an example, when the probe deviates from the detection position, the difference between the two detectors and the measured surface distance is Δl, if Δl is greater than the system deviation threshold, the controller sends a forward or reverse command to the corresponding motor. After the motor executes the command, the probe rotates and moves accordingly until Δl is less than the threshold set by the system, and the probe angle and attitude have been adjusted to the best detection position. Driven by horizontal and vertical displacement motors, the probe can be adjusted and positioned to the best system detection position.

The detailed steps of the control algorithm of the probe automatic tracking and positioning system work of the present invention are as follows:

Fig. 6 is a specific example of the present invention, which shows that the position detector detects the distance from the probe to the sample surface, and calculates the detection distance difference between the photodetector 9 at position A and the photodetector 11 at position C on the diagonal line Δl _AC = L _A - L _C, the detection distance difference between photodetector 10 at B position and photodetector 12 at D position Δl _BD =L _B -LD _, if |Δl _AC |>threshold value, and Δl _AC <0, it will be sent to the horizontal motor through the controller Forward rotation command until |Δl _AC |<=threshold value; if |Δl _AC |>threshold value, and Δl _AC >0, the controller sends a reverse rotation command to the horizontal motor until |Δl _AC |<=threshold value, rotate The angle is recorded as: θ _level . In the same way, the rotation angle of the pitch motor can be controlled by detectors B and D: denoted as: _θpitch . When Δl _AD and Δl _BC are both less than the specified threshold, then determine the vertical distance L between the probe and the sample surface at this time, L=( _LA + L _B + L _C + L _D) /4, ΔL _standard = L - standard Distance, calculated by ΔL _standard , ΔLx, ΔLy, ΔLx is the lateral movement distance of the probe driven by the lateral displacement linear motor, ΔLy is the longitudinal movement distance of the probe driven by the vertical linear motor, that is, the probe is pushed forward toward the sample surface. After these steps, the probe It is perpendicular to the sample surface, and the distance from the sample surface meets the system detection requirements.

The process of probe adjustment is as follows:

At the beginning of the detection, the probe is at the initial position 1. If the position detector detects that the probe is not vertically aligned with the detection surface, according to the calculated rotation _angle θ of the horizontal rotation motor and the rotation angle θ _pitch of the pitch rotation motor, respectively, in their respective attitudes The direction completes the corresponding rotation angle, and the probe completes the angle and _posture adjustment so that the normal line of the probe is perpendicular to the detection surface, and then _the position of _the probe is moved. The ΔLx, _ΔLy , and lateral The displacement motor and the longitudinal displacement motor move the probe in the horizontal and vertical directions respectively by ΔLx and ΔLy. At this time, the probe is perpendicular to the detection surface and the distance from the surface is a specified value, and the probe can be detected. Through the above series of detection, calculation and motor drive , so as to complete the probe automatic tracking and positioning control process.

Claims (1)

1. the automatic track and localization control system of optic probe of the optical coherent chromatographic imaging detected for mural painting, comprise optic probe clamping device (8) and infrared optics probe (1), it is characterized in that: set gradually A position photodetector (9) at the four-quadrant of the surrounding of described infrared optics probe (1), B position photodetector (10), C position photodetector (11) and D position photodetector (12), described infrared optics probe (1) is clamped by described optic probe clamping device (8), pitching electric rotating machine (5) is provided with in described optic probe clamping device (8), horizontally rotate motor (4), length travel stepper motor (6), transversal displacement stepper motor (7) and Programmable Logic Controller, the input end of this Programmable Logic Controller and described A position photodetector (9), B position photodetector (10), C position photodetector (11) is connected with the output terminal of D position photodetector (12), the output terminal of described Programmable Logic Controller and described pitch orientation electric rotating machine (5), horizontal direction electric rotating machine (4), stepper motor (6) is moved in length travel, the control end that transversal displacement moves stepper motor (7) is connected.