REVERSAL SYSTEM FOR A SURGICAL INSTRUMENT

A reversal system for a surgical instrument including: first and second outer achromats each having, first and second lenses, and first and second inner achromats arranged between the first and second outer achromats. Each of the first and second inner achromats having first and second lenses. A first pair of the first outer achromat and the first inner achromat being arranged symmetrically with respect to a second pair of the second outer achromat and the second inner achromat.

BACKGROUND

Field

The present disclosure relates to a reversal system and more particularly to a reversal system for use with a surgical instrument, such as an endoscope. Moreover, the present disclosure relates to a use of a reversal system. Still further, the present disclosure relates to a surgical instrument, such as endoscope, as well as a method of operating a surgical instrument, such as an endoscope.

Prior Art

As is known in the prior art, rigid endoscopes normally have an optical system which consists of an objective, an eyepiece and a relay lens system arranged therebetween, wherein the relay lens system has several reversal systems. Normally, an uneven number of reversal systems is provided since the objective and each reversal system generates a reversed image, and a normal endoscope should generate an upright image, whereby the generated image is orientated upright. In order to correct significant imaging errors, a symmetrical design of reversal systems is provided.

For example, a reversal system for an optical system of a rigid endoscope is known from DE 11 2004 002 220 B4. Furthermore, DE 10 2012 200 146 A1 describes a reversal system for an endoscope with a plurality of equivalent reversal systems.

Moreover, it is known that lengthened endoscopes (e.g. laparoscopes) with additional shorter reversal systems as minimal invasive surgery instruments are provided or used for bariatric surgeries.

SUMMARY

It is an object to provide, optics having a small (outer) diameter and a short length for bariatric surgical instruments, such as a laparoscope or the like, with an enhanced resolution and which may be inexpensive. Another object is to provide a surgical instrument for bariatric surgeries with improved optical properties or performance.

Such object can be solved by a reversal system for a surgical instrument, such as an endoscope, with two outer achromats, which can be exclusive, each having, two lenses, which can be exclusive, and with two inner achromats, which can be exclusive, arranged between the outer achromats, each of the inner achromats having two lenses, which can be exclusive, the pairs with one outer achromat and one inner achromat each being arranged symmetrically with respect to one another, wherein the reversal system satisfies the following condition:

L*NA2D2*(ΦRM⁢S+❘"\[LeftBracketingBar]"PTZ❘"\[RightBracketingBar]"10)>5,wherein:L is a length of the reversal system/mm,NA is a numerical aperture,D is an (outer) diameter of the reversal system/mm,ΦRMSis the minimum RMS (Root Mean Square) spot diameter at the center/mm, which can be polychromatic,|PTZ| is an absolute value of a (third order) curvature of a Petzval surface, wherein PTZ is given by the formula

PTZ=-S4I2wherein S4is a Petzval sum (third order) and I is a Helmholtz-Lagrange invariant.

An optical system is provided as a reversal system for a surgical instrument, for example, a 5.4 mm laparoscope or the like, which has a small diameter, e.g. <4 mm, and a short length, wherein the optical quality of the reversal system is enhanced in the center and especially at the edges. In addition, the reversal system also provides high resolution while maintaining high brightness and contrast. The length of the reversal system, the (outer) diameter of the reversal system and the minimum RMS (Root Mean Square) spot diameter at the center are each expressed in millimeters (mm).

With the reversal system, the mentioned formula takes into account the quality of the system at the center and at the edge as well as ratio of total length and brightness.

The outer achromats as well as the inner achromats can be configured as glued or cemented doublet achromats.

According to a further embodiment of the reversal system, the lenses of the inner achromats and the lenses of the outer achromats can have the same diameter, such as the same outer diameter.

The diameter of the lenses of the inner achromats and the diameter of the lenses of the outer achromats can be less than 4.00 mm. For example, the diameter of the lenses can be 3.75 mm.

The inner achromats can each have a negative lens (diverging lens) and a positive lens (converging lens) and/or the outer achromats can each have a negative lens (diverging lens) and a positive lens (converging lens).

Such object can also be achieved by a use of a reversal system, as described above, for a surgical instrument, such as an endoscope, for performing a surgical operation, such as a bariatric operation. The surgical instrument can be configured with at least one above-described reversal system. To avoid repetitions, explicit reference is made to the statements above.

Such object can also be solved by a surgical instrument, such as an endoscope, with at least one reversal system, wherein the endoscope can be provided with at least one reversal system, as described above.

Such object can also be solved by a method of operating a surgical instrument, such as an endoscope, for performing a surgical operation, such as a bariatric operation, wherein the surgical instrument can be provided with a reversal system, as described above. In order to avoid repetitions, reference is expressly made to the above statements.

DETAILED DESCRIPTION

FIG.1schematically illustrates a reversal system2for a schematically identified surgical instrument1. The surgical instrument1can be provided as a laparoscope or an endoscope. The surgical instrument1can be configured as a rigid surgical instrument.

The reversal system2in this case is a component of an optical system of the surgical instrument1. The optical system of the surgical instrument1in this case can be arranged in a rigid tube (not shown). The optical system of the surgical instrument1may comprise an objective at the distal end, wherein the image generated by the objective is transmitted for example using a plurality of reversal systems to an image plane at the proximal end on which the image may be viewed by an eyepiece. A camera can also be arranged on the eyepiece.

The reversal system2shown inFIG.1of the optical system of the surgical instrument1transmits the image from a first image plane3.1to a second image plane3.2. The image, which is present in the image plane3.1, is shown in reverse on, or respectively in, the image plane3.2. In so doing, the image of the image plane3.1is inverted in the image plane3.2.

The reversal system2has first and second outer achromats10,20between which two inner achromats30,40are arranged. A first outer achromat10comprises a biconcave lens11and a biconvex lens12. Correspondingly, a second outer achromat20has a biconcave lens21and a biconvex lens22. The lenses11,12of the first outer achromat10as well as the lenses21,22of the second outer achromat20can be configured circular in cross-section, i.e., perpendicular to the plane of the drawing (perpendicular to an optical axis O), and have in this case a constant (outer) diameter D, for example 3.75 mm.

First and second inner achromats30,40are arranged between the first and second outer achromats10,20each have a convex-concave lens31,41, as well as a biconvex lens32, or respectively42. The lenses31,32of the first inner achromat30as well as the lenses41,42of the second inner achromat40can be configured circular in cross-section, and have the same diameter D as the first and second outer achromats10,20. The reversal system2with the first and second outer achromats10,30and the first and second inner achromats20,40has a length L, which is the distance between the image planes3.1and3.2.

The first and second inner achromats30,40, or respectively, the lenses31,32,41,42of the first and second inner achromats30,40can be arranged in a sleeve or in a shaft (or the like) and accommodated therein.

The first and second outer achromats10,30and the first and second inner achromats20,40are arranged symmetrically to each other. Thus, the pair with the first outer achromat10and the first inner achromat30is arranged symmetrically with the other pair with the first outer achromat20and the first inner achromat40.

The reversal system can satisfy the following condition

L*NA2D2*(ΦRM⁢S+❘"\[LeftBracketingBar]"PTZ❘"\[RightBracketingBar]"10)>5,whereinL is the length of the reversal system2/mm,NA is the numerical aperture of the reversal system2,D is the (outer) diameter of the reversal system2/mm,ΦRMSis the minimum, in particular polychromatic, RMS (Root Mean Square) spot diameter at the center/mm,|PTZ| is the absolute value of the (third order) curvature of the Petzval surface, wherein PTZ is given by the formula

PTZ=-S4I2,wherein S4is the Petzval sum (third order) and I is the Helmholtz-Lagrange invariant. The length of the reversal system, the (outer) diameter of the reversal system and the minimum RMS (Root Mean Square) spot diameter at the center are each specified in millimeters (mm).

FIGS.2aand2bshow the modulation transfer functions (MTF) of an optical system with the reversal system2according to the present disclosure (seeFIG.2a) and a bariatric optical system (according to the prior art) (seeFIG.2b). The horizontal axis shows the spatial frequency (lp/mm), and the vertical axis shows the MTF, also contrast.

The MTF describes the optical system in terms of contrast at different spatial frequencies, expressed in line pairs per mm (lp/mm). Higher spatial frequencies correspond to finer details. An MTF value of 1 means perfect contrast, 0 is no contrast at all, white and black lines cannot be distinguished anymore at all.

Generally, the solid lines represent MTF in the tangential direction and the dashed lines represent MTF in the sagittal direction. MTF a/a′ represented by dotted lines represent the theoretical ideal case of a diffraction-limited system of each optics. As can be seen inFIG.2b, even the theoretical optimum involves the MTF decreasing rapidly towards finer details.

Lines b and b′ denote the MTF in the center of the image plane, which is the same in the sagittal and tangential directions. Lines c, c′ and d, d′ denote the MTF at 80% image height in the tangential and sagittal directions, respectively, lines e, e′ and f, f′ the MTF at 100% image size, i.e., at the far edge.

As can be seen inFIG.2b, the MTF of the bariatric optical system has worse MTF values, especially the contrast (MTF) at the edge areas become catastrophic.

In the case of an optical system with the reversal system2according to the present disclosure, shown inFIG.2a, the values are significantly better, not only on the center area, also on the edge area. The MTFs are overall significantly improved, especially at high spatial frequencies, leading to clearer and more detailed images.

LIST OF REFERENCE SIGNS