RU2087017C1 - Achromatic lens for great magnification microscope - Google Patents

Abstract

FIELD: large-scale production of microscopes. SUBSTANCE: device has frontal member which is designed as first position flat-convex or meniscus lens and second positive meniscus. Convex region of both lenses are directed towards image. In addition device has two double-glued lenses, which convex region of positive members is directed towards image. In addition device has last member which is designed as single meniscus which concave region is directed towards image. It conforms to conditions

. Focal length of first lens of front member is equal to

, where R1, R2, D, Ye are respectively curvature radiuses, depth and dispersion coefficient of last member. In addition device may have additional aperture which opening diameter is equal to diameter of lens output aperture. Distance between this additional aperture and last member is varied in range of

Description

 The invention relates to optics and can be used in the design of large-magnification achromatic lenses for the assembly of large-scale microscopes such as BIOLAM, BIMAM, LUMAM.

 A known lens / 1 /, in which the chromatic difference of magnifications / HRI / is reduced and the image curvature is reduced.

 However, in this case, the image is stained in the intermediate plane of the microscope, and the residual curvature remains significant. Moreover, in this lens there is no possibility of further increasing the numerical aperture / resolution / to a maximum value of 1.35-1.4 oil immersion.

 These shortcomings lead to a decrease in information capacity on a microscope and do not allow to increase the performance of microscopic studies.

 Closest to the invention is a micro lens / 2 / having a fairly simple design, suitable for large-scale production. The lens contains a frontal component in the form of single positive first plano-convex and second meniscus lenses convex to the image space, two double-glued from negative and positive space-facing lenses, and the last component in the form of a negative two-glued meniscus facing concavity to the image space.

 At the same time, it is distinguished by a number of disadvantages that do not allow recommending it for use. Thus, insufficient correction of monochromatic aberrations of off-axis beams leads to a decrease in the useful field of view, observed without refocusing. Inadequate correction of HRU does not allow the use of an eyepiece that is simple in design with a linear field of view 2y '= 18-20 mm. A reduced numerical aperture in the space of objects reduces the destructive ability of the lens. All of these shortcomings cause a reduced information capacity. At the same time, the optical scheme does not allow to eliminate the listed disadvantages. So, the implementation of the last component glued determines the appearance of difficult to fix spherochromatic aberrations / when trying to increase the aperture /, and the first lens of the front component is not optimal for the correction of monochromatic aberrations of off-axis beams.

 At the same time, in modern models of microscopes, the use of micro-lenses with increased information capacity is required due to the improvement of the aberration correction of monochromatic aberrations of off-axis launches, a decrease in CRI, and an increase in resolution.

R₁=/1,3-1,5/R₂;
D=/0,7-1,2/R₂,
20< ν_e <30,
и фокусное расстояние первой линзы фронтального компонента составляет

Кроме того, на варьируемом расстоянии

от последнего компонента располагается материальная диафрагма с диаметром раскрытия, равным диаметру выходного зрачка объектива.These requirements are met by the achromatic lens of a large magnification microscope, the design of which, like the prototype, includes a frontal component in the form of single positive first plano-convex or meniscus and second meniscus lenses convex to the image space, two double-glued from negative and positive, facing the image space , lenses, and the last component in the form of a meniscus, facing concavity to the space of images. However, unlike the prototype, in the proposed lens, the last component is single, and in it the following ratios are satisfied:

R ₁ = / 1.3-1.5 / R ₂ ;
D = / 0.7-1.2 / R ₂ ,
20 <ν _e <30,
and the focal length of the first lens of the front component is

Also at a variable distance

from the last component there is a material diaphragm with an opening diameter equal to the diameter of the exit pupil of the lens.

 The use of the last component of the meniscus with the indicated signs of execution allows the correction of monochromatic aberrations of the axial and off-axis beams. The implementation and location of it in the specified manner eliminates chromatic aberration and reduces the curvature of the image. As a result, the simultaneous correction of monochromatic and chromatic aberrations occurs, while the correction of monochromatic aberrations leads to the possibility of increasing the aperture / resolution /, and reducing the curvature of the image will increase the area of the sharply observed field without refocusing. Correction of chromatic aberrations reduces the color of the intermediate image and makes it possible to use an eyepiece of a simple design, and the CRU decreases significantly, about 5.7 times.

 The location at a variable distance L behind the meniscus of the material diaphragm with an opening diameter equal to the diameter of the exit pupil of the lens allows optimal correction of astigmatism and curvature / their rebalancing /, deflecting the main beam in the lens. Moreover, the variable distance L allows for optimal rebalancing of astigmatism and to achieve the sharpest image on a microscope when observed by a specific observer. In the case where simplified constructions are required, the role of the diaphragm can be performed by the mechanical frame of the output end of the micro-lens.

 The simultaneous correction of chromatic and monochromatic aberrations makes it possible to increase the information capacity of the lens in proportion to the increase in the field of view that is sharply observed without refocusing and in proportion to the increase in resolution.

 The drawing shows an optical diagram of the inventive lens.

 The lens contains a front component 1, component 2, made in the form of two double-glued lenses sequentially located along the optical axis, the positive components of which face the image plane, and also component 3 located behind component 2, containing a single meniscus, the design of which satisfies the relations indicated in the formula . The material diaphragm located behind it at some variable distance has an opening diameter equal to the diameter of the exit pupil of the lens.

 The lens works as follows.

 The first component constructs an enlarged imaginary image of the object with reduced values of the aberrations of the axial point and a negative value of the meridional and sagittal curvature. Component 2 builds a real image of the object in the focal plane of component 3. At the same time, negative values of spherical aberration, slight curvature, and significant chromaticity of the position and magnification are introduced. Then the image is intercepted by component 3, which builds the image at infinity. In this case, the monochromatic and chromatic aberrations of the previous components are compensated.

In the framework of the proposed technical solution, calculations of a whole gamut of achromatic large-magnification lenses were performed. Received immersion lenses with a magnification of 100 ^x . The aperture of one of them is 1.25 mm, the CCD is reduced to 0.3%, which increases the information capacity on the microscope by about 1.5-2 times, the aperture of the other is 1.4 mm, which in combination with the reduced CCP also increases the information capacity on a microscope about 1.5-2 times.

Claims (2)

1. Achromatic microscope lens of large magnification, containing the front component in the form of single positive first plano-convex or meniscus lenses and the second meniscus convex to the image, two double-glued from negative and positive, facing the image lenses and the last component in the form of a meniscus, facing concavity to the image, characterized in that the last component is made single, and it satisfies the ratio

and the focal length of the first lens of the front component is

where R ₁ , R ₂ , D, ν _e are the radii of curvature, thickness and dispersion coefficient of the material of the last component, respectively;

focal length of the lens. 2. The lens according to claim 1, characterized in that at a variable distance

from the last component there is a material diaphragm with an opening diameter equal to the diameter of the exit pupil of the lens.