GB2129957A

GB2129957A - Microtome knife-checking arrangement

Info

Publication number: GB2129957A
Application number: GB08316138A
Authority: GB
Inventors: Walter Bilek
Original assignee: C Reichert Optische Werke AG
Current assignee: C Reichert Optische Werke AG
Priority date: 1982-06-30
Filing date: 1983-06-14
Publication date: 1984-05-23
Also published as: DE3224375C2; SE8303690D0; GB8316138D0; FR2529678A1; SE8303690L; GB2129957B; CA1190446A; JPS5913941A; ATA211883A; DE3224375A1

Abstract

A device for checking the quality of a knife 3 in a microtome, in particular an ultramicrotome, in which the microtome has an observation microscope 4 and a sublevel light source 6 for illuminating a specimen/ knife region, the knife being carried by a knife-holder 12, which can be pivoted about an axis lying along the cutting edge of the knife between a specimen-cutting position and a tilted position in which the exposed surface of the cutting edge of the knife and the optical path of the sublevel light source define an included angle of at least 20 DEG . The knife-holder can be locked in this tilted position. <IMAGE>

Description

SPECIFICATION Microtome kni8e-checking arrangement The invention relates to microtomes, especially ultramicrotomes. More particularly the invention concerns an arrangement for checking the knife in such a microtome.

The quality of the thin sections which can be produced by means of a microtome depends substantially on the quality of the cutting edge of the knife. Particularly in the case of ultramicrotomes, in which glass knives are normally used, it is important to inspect the knife for damage (e.g. chipping, edge serration) and contamination, before carrying out cutting operations. Inspection of the knife is usually carried out under dark-field illumination. This is achieved in known ultramicrotomes, by making the microscopes and/or the sublevel illumination system adjustable, or the knife is clamped at a more oblique angle in the knife-holder for the purpose of being checked.It is also known to install on the ultramicrotome an additional spotillumination light for checking the quality of the cutting edge, this light providing illumination of the cutting edge obliquely from above.

These known methods of checking the quality of the cutting edge are either troublesome or necessitate additional hardware, since it is necessary first to swing the observation microscope, and/or the sublevel light source, into the position in which the condition for the precise viewability of the cutting edge of the knife is satisfied, after which they must be returned to the normal position required for cutting.

An object of the present invention is to provide an arrangement which enables the quality of the cutting edge of the knife to be checked, in a simple manner and without any significant additional expense.

According to the present invention we provide a microtome comprising a knife for cutting thin sections of a specimen, an observation microscope and a sublevel light source directed onto the cutting edge of the knife, an arrangement for checking the knife comprising a knife-holder which is arranged to be pivoted about an axis lying along the cutting edge of the knife between a specimen-cutting position for cutting sections and a second tilted position in which the exposed surface of the cutting edge of the knife and the optical path of the sub-level light source define an included angle of at least 200.

In the known ultramicrotomes of the type described above the knife-holder can be pivotably adjusted, but this facility is used only for the purpose of setting the lead angle of the cutting edge of the knife, the angle between the exposed surface of the knife and the sectioning surface of the specimen, to the most advantageous value for the specimen in question. As a rule, this angle does not exceed 100, for which reason the pivoting capability of the knife-holder is limited to 1 50, referring to the zero point defined by the arc over which the specimen arm of the ultramicrotome can swing.

The present invention starts from the realisation that it is possible, by markedly increasing the tilting range of the knife-holder, without incurring significant additional expense, to shift the exposed surface of the knife into that position which guarantees clear viewability of its cutting edge, for the purpose of checking it, and to lock it in that position, thus dispensing with the need for any additional movement capability of the observation microscope and/or of the sublevel light source. To achieve the desired result, the minimum angle through which movement must be possible is 200, but a larger angle is advantageous.

An illustrative embodiment of the invention is described below with reference to the drawings, in which: Figure 1 is a diagrammatic cross-sectionai representation of an ultramicrotome; and Figures 2 and 3 are diagrammatic detailed representations of the knife-holder, in the tilted position which permits the cutting edge of the knife to be checked, and in the cutting position respectively.

The ultramicrotome shown in Figure 2 comprises a specimen arm 1, which can be moved up and down, and on which a specimen, or preparation, 2 is secured. During the up and down movement, the specimen 2 is guided past the cutting edge of a knife 3 so as to produce thin sections. An observation microscope 4 is provided for observing the cutting process, and for checking the knife, the optical axis of this microscope being designated 5. In order to illuminate the knife/specimen region, a sublevel light source 6 is located inside the ultramicrotome, the light beam from the light source 6 being deflected, by a deflecting mirror 7, to provide an upwardly directed optical path 8.

The ultramicrotome shown in Figure 1 is of known design and for this reason details of its construction are not described.

Figures 2 and 3 show, on a larger scale, the arrangement for providing the tilting movement of the knife 3. Beneath its cutting edge 3', the knife 3 carries a delivery trough 11. When the ultramicrotome is being operated, a liquid is provided in the trough 11 to receive the thin sections which are cut from the specimen by the cutting edge 3' of the knife. A knife-holder 12, which grips the knife 3 in a known manner, is carried by a rocker 13, which can slide in a cylindrical slideway 14 on the support of the ultramicrotome. Movement of the rocker 1 3 in the slideway 14 causes the knife-hoider 12 and the knife 3, to pivot about the cutting edge 3' of the knife.

By the above means, it is possible to set the angle of the exposed surface 1 5 of the knife 3 in relation to the sectioning surface of the specimen 2 (this surface is not shown in Figures 2 and 3), and also to set the angle a (Figure 2), which is required in order to observe the cutting edge 3' of the knife.

Setting is carried out by means of an eccentric rotary knob 16 (shown diagrammatically in Figures 2 and 3), the eccentric pin of the knob acting on an end face of the rocker 13. The eccentricity of the eccentric pin is chosen such that, in the tilted position of the knife-holder 12 shown in Figure 2, the exposed surface 15 and the optical axis 8 include an angle a of at least 200.

This angular position is sufficient to enable the cutting edge 3' of the knife 3 to be viewed clearly, to check the quality of the edge, without altering the optical axis 5 and/or the optical path 8.

Although not shown in detail in the drawing, it is evident that the knife-holder 12 can be locked, by means of suitable clamping devices, both in the tilted position shown in Figure 2, and in the cutting position shown in Figure 3.

Claims

1. In a microtome, comprising a knife for cutting thin sections of a specimen, an observation microscope and a sub-level light source directed onto the cutting edge of the knife, an arrangement for checking the knife comprising a knife-holder which is arranged to be pivoted about an axis lying along the cutting edge of the knife between a specimen-cutting postion for cutting sections and a second tilted position in which the exposed surface of the cutting edge of the knife and the optical path of the sublevel light source define an included angle of at least 200.

2. An arrangement according to Claim 1 in which the included angle does not exceed 450.

3. An arrangement according to Claim 1 in which the knife-holder is located in a cylindrical slideway and an eccentric device is provided to move the knife-holder between its specimencutting and its tilted positions.

4. A microtome substantially as herein described with reference to and as shown in the accompanying drawings.