DD251497A1 - DEVICE FOR MEASURING THE CRUISES OF TORQUE REFLECTIVE FLAKES, IN PARTICULAR THE EYE FORESTRY - Google Patents

Abstract

A highly accurate measurement with the least amount of effort is realized in images of test objects, which are imaged in the image plane of an optical observation and measuring device, on the toric surface, by imaging the test objects on the toric surface through collimators lying on three meridian planes to the observation beam path takes place whose beam path encloses an angle with the observation beam path. Fig. 2

Description

For this 1 page drawings

Field of application of the invention

The invention relates to a device for measuring the curvature of toric reflecting surfaces, in particular the cornea of the eye, wherein images of test objects generated in the image plane of an optical observation and measuring device are imaged on the theoretical surface.

Characteristic of the known technical solutions

It is already known (DR 539515), using two collimators arranged at an angle to each other, to map test figures to the human eye irrespective of distance.

The measurement is carried out by separating two partial beams of light from the imaging (reflected) beam by optical means and deflecting them measurably.

For the measurement of the two radii of curvature of a toric surface, the alignment of the meridian described by the test figures is required parallel to the main sections of the surface, since a defined refractive power is present only in the main cutting axes.

This requires a rotation of the device, d. H. additional work and the realization of a precise device rotation.

Furthermore, it is known (DE-OS 2530085) to realize an annular illumination of the cornea by appropriately arranged individual light sources.

The visual evaluation of the observed image leads due to its deformation to a qualitative statement about the corneal astigmatism. A quantitative measurement would give only a low accuracy.

Object of the invention

The aim of the invention is to realize a high-precision measurement of the curvature of toric surfaces with minimal effort.

Explanation of the essence of the invention

The object of the invention is, while avoiding rotation of the device or the eyepiece, i. without the search of the main cutting axes to realize the measurement of the curvature.

According to the invention the object is achieved by the features of the first claim.

Preferred developments are described in the subclaims.

The arrangement in three fixed meridians, the size of the image of a test object in any position to the main sections of a toric surface mathematically determined by the location of their major sections and the size of their radii of curvature.

From the size of the images of the three test objects, the position of the two main sections of the toric surface as well as the size of the radii of curvature corresponding to them clearly result.

An alignment of the device after the main sections of the surface to be measured is no longer necessary.

embodiment

The invention will be explained in more detail below with reference to the schematic drawings. Show it:

1: an embodiment of an ophthalmometer according to the invention (side view) FIG. 2: a front view FIG. 3: an eyepiece image

In Fig. 1, collimators 2a-f are arranged in three fixed meridians, which are at an angle of 60 ° to each other.

The three test objects which they represent are imaged by the surface 1. This visual image is imaged by an imaging optical system 3 as image 5. In Figure 5, the size of the three test objectives can be measured in a known manner. 4 is the optical axis of the device.

In the position of the image 5 or in conjugate planes, one or more spatially resolving photoreceivers can be arranged, by means of which the size of the image of the three test objects represented by the bar marks is measured.

FIG. 3 shows an eyepiece image with the reflection images 6 of six test marks on an astigmatic cornea. The measured value scales 7 can be replaced by position-sensitive photoreceivers. The radii of curvature of the cornea in its main sections and the axial position are calculated from the measured values in the three measuring meridians as follows.

λ -i

for κ ¹ = max. φ = φ '+ 90 °

for κ ² = max. and 30 ° <φ '<45 ° is φ = φ' + 90 °

for κ ² = max. u. -45 ° <φ '<0 ° is φ = φ' + 180 °

for κ ³ = max. υ.0 ° <φ '<45 ° is φ = φ'

for κ ³ = max. u-45 ° <cp '<- 30 ° is φ = φ' + 90 °

There are:

- κ ¹ , κ ² , κ ³ - the measured values of the curvature of the cornea in the three measuring meridians

- κ ¹ , u. κ ² - the curvatures of the cornea in its two main sections (κ = -, r-radius of curvature)

- φ - angle between 1st measuring meridian and axis of the plus cylinder

Claims (4)

1. A device for measuring the curvature of toric reflecting surfaces, in particular the cornea, wherein images of test objects are imaged on the optical surface in the image plane of an optical observation and measuring device, characterized in that the image of the test objects on the toric surface by three Meridian planes to the observation beam path lying collimators takes place whose beam path with the observation beam path in each case encloses an angle. 2. Apparatus according to claim 1, characterized in that the meridian planes enclose an angle of 60 ° with each other. 3. Apparatus according to claim 1 or 2, characterized in that in the image plane of the observation and measuring device at least one spatially resolving photoreceiver is arranged. 4. Apparatus according to claim 1 and 3, characterized in that the photoreceiver is arranged in a plane conjugate to the image plane.