RU147266U1 - DEVICE FOR SCANNING SUPPORT SHOULDER OF OPTICAL COORENT TOMOGRAPH - Google Patents

Abstract

A scanning support arm of an optical coherent tomograph containing a single-mode optical fiber, which is the only input and output for radiation, an optically coupled collimator lens, a diffraction grating with an adjustable angle of inclination, a scanning mirror with an adjustable angle of inclination, and a double-pass mirror, characterized in that the collimator lens is mounted in a double-pass mirror so as to maintain its mutual perpendicularity with the end face of a single-mode optically coupled to a collimator lens etovoda, using the dichroic focusing lens, wherein the scanning mirror is placed on the focal length from it.

Description

The proposed technical solution (utility model) relates to the field of optical devices or devices using movable optical elements to control the intensity, color, phase, polarization or direction of light, in particular to scanning systems and can be used in optical coherence tomography to scan the measurement volume by depth.

In optical coherence tomography, the internal structure of a biological object is restored by selection of reflected radiation at the depth with which it came and the degree of reflection on it. To this end, the waves from the supporting shoulder and from the shoulder of the sample are compared. The support arm is made in such a way that the reference wave is compared each time with the fraction of radiation coming from different depths inside the sample (bioobject), i.e. the support arm provides a multiple controlled change in the length of the optical path that the reference wave travels. For this, an optical delay line based on a scanning mirror or a galvanic scanner is used.

According to the patent US 6654127 B2, IPC G02B 6/34, G01N 21/45, G01B 11/24, A61B 10/00, G01N 21/17, G02B 26/00, G01B 9/02, G01B 9/023, G02F 1 / 11, G02B 26/10, publ. 11/25/2003, the device of the optical delay line is known, intended for use mainly in coherent optical reflectometry in the time domain and optical coherence tomography, including many optical elements in optical communication with each other, in which: at least one of the many optical elements is able to spatially separate light waves, i.e. provide spatial dispersion of the optical signal; at least one of the plurality of optical elements can be adjusted, i.e. affect the phase and group delay of the optical signal; at least one of the plurality of optical elements compensates for the dispersion of a wide spectrum of the radiation source of at least one of the optical elements spatially separating light waves. The technical result of using the device is to provide an adjustable time delay of optical radiation.

The disadvantage of this device is the low spatial resolution caused by insufficient focusing of radiation back to the tip (end) of the optical fiber, which in turn leads to incomplete restoration of collimated radiation and, accordingly, loss of a portion of the useful signal.

According to patent US 20090279171 A1, IPC A61B 5/00, G11B 7/005, A61B 3/12, G11B 7/085, G01B 11/02, G01B 11/00, G11B 7/24, G01B 11/12, G11B 7 / 125, G11B 7/135, G01J 1/00, H01S 5/14, G11B 7/00, G01N 21/47, G01B 9/02, G02B 27/44, G01B 11/24, A61B 5/103, G02B 5 / 18, A61B 3/10, publ. 11/12/2009, it is known that an optical delay line device is universal for various optical systems, in which in one embodiment, along the optical path (from the optical input to the optical output), the light is sequentially orthogonally reflected by the first, second and third reflective surfaces of the linearly movable section and exits through part of the section in the direction opposite to its original direction. In another embodiment, a more complex radiation routing is used: the light is sequentially orthogonally reflected by the first, second and third reflective surfaces of the linearly movable section and by means of an auxiliary movable section located approximately parallel with respect to at least either the optical input or the optical output, goes in the opposite direction of his arrival. The technical result of the use of the device is the provision of a time-controlled delay of optical radiation.

The disadvantages of this device is the inability to compensate for the dispersion and separation of the phase and group delay, as well as the low spatial resolution caused by the separation of the optical input and optical output.

The closest analogue (prototype) of the developed utility model is a scanning optical delay line device (patent US 6111645 A, IPC A61B 5/00, G11B 7/005, A61B 3/12, G11B 7/085, G01B 11/02, G01B 11/00 , G11B 7/24, G01B 11/12, G11B 7/125, G11B 7/135, G01J 1/00, H01S 5/14, G11B 7/00, G01N 21/47, G01B 9/02, G02B 27/44 , G01B 11/24, A61B 5/103, G02B 5/18, A61B 3/10, publ. 08/29/2000) for optical interferometry, including optical coherence tomography, in which the time delay of optical radiation is achieved using diffraction optical elements in combination with elements for forming images. In one embodiment, the diffraction grating decomposes in terms of frequency or wavelength delivered by an optical fiber and collimated by a lens light beam. A mirror placed at the focal length from the focusing lens and a diffraction grating with variable stroke density, gloss angle, and also the angle of the overall tilt of the grating and / or the angle of tilt of the mirror produce a change in the group and phase delay. In other embodiments, the implementation of this device allows you to scan with a time delay without using moving parts. The technical result of using the device is to provide an adjustable group and phase delay for each position during the angular movement of the scanning mirror.

The disadvantage of this device is also the low spatial resolution caused by insufficient focusing of radiation back to the tip of the optical fiber.

The technical task of the utility model is to increase the spatial resolution of scanning in depth, by organizing a more efficient focusing of radiation at the tip of the optical fiber, leading to better recovery of collimated radiation and, accordingly, reducing the loss of the useful signal.

The stated technical problem is achieved by the fact that the device of the scanning support arm of the optical coherent tomograph, as well as the device, which is the closest analogue, contains a single-mode fiber, which is the only input and output for radiation, an optical diffraction lens, a collimator lens tilt grille, scan tilt mirror and double pass mirror.

A novel feature in the developed device of the scanning support arm of an optical coherent tomograph is that the collimator lens is rigidly articulated with a double-pass mirror so as to maintain its mutual perpendicularity with the end face of a single-mode fiber optically coupled to the collimator lens, and a focusing dichroic lens is used, the scanning the mirror is placed at the focal length from it.

Figure 1 presents the implementation diagram of the developed device scanning reference arm of an optical coherent tomograph in accordance with the formula of the utility model.

The principle of operation of the device of figure 1. following. From a single-mode fiber, the radiation enters the collimator lens, with its help it is converted into parallel rays and gets on the diffraction grating, where they decompose. Then the rays are focused by the edge of the focusing dichroic lens and then fall on the scanning mirror (or on the mirror of the galvanic scanner). Reflected from it, they pass through the center of the lens, again decompose on the diffraction grating and enter a double-pass mirror, reflected from which the radiation is focused, and return almost along the same path (within the error) to the tip of the fiber. The ability to vary the angles of inclination of the diffraction grating (angle α) and the scanning mirror (angle β) allows you to effectively adjust the focusing and scanning processes.

The most important distinguishing feature of the proposed utility model is that after the radiation is decomposed into a spectrum by a diffraction grating, it will fall on the edge of a focusing dichroic lens, which in its optical properties is largely similar to a truncated prism, as a result of which light rays incident there are very efficiently collected the focus point of the lens (this is where the scanning mirror is located), i.e. a focusing dichroic lens behaves the same as a conventional biconvex lens. But, a focusing dichroic lens has the property of focusing a wider spectrum of radiation from light sources than a conventional focusing lens, and therefore is better suited to the needs of optical coherent tomography, where, as a rule, broadband radiation sources are used.

Another claimed distinctive feature is the rigid articulation of the collimator lens and the double-pass mirror. It is explained by the geometry of the optical bonds between the structural elements of the proposed utility model, and allows one to preserve the mutual perpendicularity of the double-pass mirror and the end face of a single-mode fiber optically coupled to the collimator lens, and thus simplify the focusing of radiation at the end of this fiber and the subsequent restoration of collimated radiation.

In a specific implementation of the developed device of the scanning support arm of an optical coherent tomograph, a meter single-mode fiber P3-980A-FC-1 (970-1650 nm, FC / APC) was used as a single-mode fiber. The F220APC-1064 collimator (1064 nm, FC / APC) was used as a collimator lens. As a diffraction grating, a GTI25-03A diffraction grating was used (300 lines / mm, brightness angle 31.7 °). Instead of a scanning mirror, a 1D galvanic scanner GVS001 was used (400-2000 nm, silver coated mirror, scanning angle ± 12.5). The focusing dichroic lens was glued from a DMLP900 dichroic filter (diameter 25.4 mm, passband 932-1300 nm) and a biconvex lens LB1757-C (diameter 25.4 mm, focal length 30 mm). All components manufactured by Thorlabs (USA).

Thus, the use of a focusing dichroic lens, in combination with a rigid joint of a collimator lens and a double-pass mirror, as well as a special mutual arrangement of the focusing dichroic lens and a scanning mirror, allows one to efficiently focus and return broadband radiation along the same optical path along which it originally came . In a specific implementation, the error did not exceed 1 micron. Since the P3-980A-FC-1 single-mode fiber has a core diameter of 5.8 microns, an error of no more than 1 micron is acceptable and allows one to organize effective focusing at the end of the optical fiber (and subsequent restoration of collimated radiation), which means reducing the loss of the useful signal and thereby increase spatial resolution of scanning in depth.

The proposed device of the scanning support arm can be used both in optical coherence tomography and coherent optical reflectometry in the time domain, and in optical interferometry as a whole.

Claims (1)

A scanning support arm of an optical coherent tomograph containing a single-mode optical fiber, which is the only input and output for radiation, an optically coupled collimator lens, a diffraction grating with an adjustable angle of inclination, a scanning mirror with an adjustable angle of inclination, and a double-pass mirror, characterized in that the collimator lens is mounted in a double-pass mirror so as to maintain its mutual perpendicularity with the end face of a single-mode optically coupled to a collimator lens etovoda, using the dichroic focusing lens, wherein the scanning mirror is placed on the focal length from it.

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