The invention can be used in eyepieces, for viewing images of micromonitors, as well as in optical coherence tomography devices. A telecentric lens consists of three elements. The first element is a single plano-convex lens, the second and third elements are glued together and form a complex composite lens, the focal length f2 of which satisfies the condition 0.35 <f2 / fc, where fc is the focal length of the system as a whole, the refractive index n3 of the negative meniscus entering in the composition of a complex lens, satisfies the condition 2.21 <n3 + 0.0176v3 <2.27, where v3 is the Abbe index for the material of the third lens for the spectral line d (0.5875618 ?m). The focal length f1 of a plano-convex lens satisfies the condition 1.7 <f1 / fc <2.2. EFFECT: improved operational characteristics with high image quality in the near infrared range, providing optical resolution close to diffraction. 3 C.p. f-crystals, 10 dwg., 2 tbl.
The proposed invention relates to optical instrumentation and can be used in the eyepieces of telescopic systems and microscopes, for viewing images of various micromonitors, for example, television or thermal imaging optical systems, as well as in optical coherence tomography devices, including for the diagnosis of a number of diseases.
A telecentric eyepiece with a remote exit pupil is known, containing a negative doublet located along the path of the rays, a positive meniscus facing the concave surface to the object plane, a positive doublet oriented with its negative lens towards the object plane, a positive lens in the form of a meniscus facing the exit pupil with a concave surface (one). Among the advantages of the development is the provision of the path of the main rays in the space of objects, close to telecentric. However, a disadvantage of the known eyepiece is the large number of image-forming elements.
A device for optical scanning with a telecentric beam path is known, consisting of six elements. However, the disadvantage of this device is the large number of elements that form the image and the insufficiently large eye relief (1/3 of the focal length).
Known three-piece two-lens eyepiece. The eyepiece contains two components, the first of which along the ray path is a two-lens, glued from a biconcave and the first biconvex lens, the second component is a single second biconvex lens. The following relations are fulfilled in the eyepiece: | R4 | <| R5 |, | R2 | = | R3 | = | R4 |, | R1 | = | R5 |, where R1, R2, R3, R4, R5 are the radii of the first, second, third, fourth and fifth optical surfaces. The refractive index of the first biconvex lens of the first component is greater than the refractive index of a single second biconvex lens of the second component. However, the disadvantage of the known eyepiece is the use of a biconvex lens on the pupil side, which is undesirable when used in optical coherence tomography devices.
The closest to the proposed device in terms of the set of essential features and the achieved technical result is a known device for optical scanning with a telecentric beam path, containing three elements, of which the first element is a single lens, the second and third elements are glued together and form a complex composite lens, the f2 focal length of which satisfies the condition 0.35 <f2 / fc, where fc is the focal length of the system as a whole, the refractive index n3 of the negative meniscus, which is part of a complex lens, satisfies the condition 2.21 <n3 + 0.0176v3 <2.27 , where v3 is the Abbe index for the material of the third lens for the spectral line d (0.5875618 ?m), and a plano-concave lens is used as the first element, the focal length f1 of which satisfies the condition -2.2 <f1 / fc <-1, 7,which is chosen as a prototype (4).
The device is characterized by a satisfactory distance between the entrance pupil and the first surface of the first element.
However, the disadvantage of the known device is insufficient resolution when used in the near infrared range. In particular, when reduced to a focal length of 32 mm, the device allows obtaining a resolution in the scanning plane not higher than 10 pairs of lines per mm at a probe radiation wavelength of 1.3 ?m.
The objective of the present invention is to create a telecentric lens that can be used as part of an optical coherence tomography device, which makes it possible to realize sufficient resolution for the purposes of diagnosing a number of diseases, including oncological ones.
The technical result is the creation of a telecentric lens with improved performance characteristics with high image quality in the near infrared range, providing an optical resolution close to diffraction.
The technical result is achieved due to the fact that in a device with a telecentric beam path containing three elements, of which the first element is a single lens, the second and third elements are glued together and form a complex composite lens, the focal length f2 of which satisfies the condition 0.35 <f2 / fc, where fc is the focal length of the system as a whole, the refractive index n3 of the negative meniscus included in the complex lens satisfies the condition 2.21 <n3 + 0.0176v3 <2.27, where v3 is the Abbe index for the material of the third lens for spectral line d (0.5875618 ?m), according to the invention, a plano-convex lens is used as the first element, the focal length f1 of which satisfies the condition 1.7 <f1 / fc <2.2.
