JPH049731A - Lens meter - Google Patents

Abstract

PURPOSE:To measure a refraction value of a lens to be detected without using a separating prism by projecting a parallel luminous flux to the lens, converging the flux through an iris, and then photodetecting it on an optical position detector. CONSTITUTION:When a refraction value of a lens L to be detected is measured, the lens L is brought into contact with a contact member 3, and fixed. Then, when a light source 1 is turned ON, a luminous flux from the source 1 is propagated on an optical axis 01 to be a parallel luminous flux by a lens 2, and then projected on the lens L. The flux of the lens L is divided into four luminous fluxes through a plurality of hole irises 4, and four projected fluxes Ma - Md are projected on an optical position detector 5. A decentriation of the lens L from the axis 01 or a prism degree in a plane perpendicular to the axis 01 from the positions of the fluxes Ma - Md is detected. Thus, the refraction value of the lens can be measured without providing a separating prism.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a lens meter used, for example, in eye clinics.

[Prior art] Lens meters include, for example, Japanese Patent Application Laid-open No. 62'-223642.
As disclosed in the publication, a parallel light beam is projected onto a lens to be tested, and the transmitted light beam is separated from the optical axis through a multi-hole aperture and a separation prism into a plurality of light beams, and then passed through a lens of a light receiving optical system. There is one that receives light on an optical position detector and measures the refraction value from the light receiving position.

[Problems to be Solved by the Invention] However, in the conventional example described above, the optical position detector is placed at the focal point of the lens of the light receiving optical system, and is located at the apparent infinity point of the multi-hole diaphragm. Therefore, a separation prism is indispensable in order to separate the received light flux on the optical position detector, which causes the configuration to become complicated.

An object of the present invention is to provide a lens meter that does not require a separation prism and is easy to configure.

[Means for Solving the Problems] In order to achieve the above-mentioned object, a lens meter according to the present invention includes a projection optical system that projects a parallel light beam onto a test lens, and a projection optical system that projects a parallel light flux onto a test lens. Light reception in which the transmitted light flux is received through a diaphragm having an aperture in at least three meridian directions around the optical axis and onto a two-dimensional optical position detector placed at a position optically separated from the diaphragm by a finite distance. The refraction value of the test lens is measured from a light beam receiving position on the optical position detector.

[Operation] The lensmeter having the above-mentioned configuration projects a parallel light beam onto the lens to be tested, receives the transmitted light beam on the optical position detector after passing through the aperture, and detects the light beam from the receiving position of the lens to be tested. Measure the refraction value.

[Example code] The present invention will be explained in detail based on illustrated embodiments.

FIG. 1 shows a configuration diagram, in which 1 is a point-like light source, and on its tip axis O1 there is a lens 2, a contact member 3 for contacting the test lens L, and a light source 1 as shown in FIG. 4 off axis 01
A multi-hole diaphragm 4 having apertures 4a to 4d, and a two-dimensional optical position detector 5 such as a CCD image sensor are sequentially arranged. The output of the optical position detector 5 is output to a television monitor.

When measuring the refractive value of the test lens L, when the test lens L is brought into contact with the contact member 3 and fixed, and then the light source 1 is turned on, the light beam from the light source 1 travels on the optical axis 01, After being made into a parallel light beam by the lens 2, it is projected onto the lens L to be tested.

The transmitted light flux of the test lens L passes through the multi-hole diaphragm 4 and is converted into four light fluxes, and four projection light fluxes Ma=Md are projected onto the optical position detector 5 as shown in FIG.

From the positions of these projection light beams Ha to Md, the eccentricity or prism degree of the lens L to be tested from the optical axis 01 in a plane perpendicular to the optical axis 01 is detected. Further, the position of the lens L to be tested can also be adjusted using the projection light beams Ma to Md on the television monitor 7. Also, the distance between the projection light fluxes Ma and Me in the meridian direction of the apertures 4a and 4c, or the distance between the apertures 4b and 4c
The distance between the projection light fluxes Wb and Md in the meridian direction is proportional to the refractive power of the test lens L in each meridian direction, and for example, the projection light fluxes Ma' to Md shown as points in the case of a concave lens.
' moves radially.

-H, it can be assumed that the refractive power of the cylindrical spherical lens changes sinusoidally with respect to the meridian direction as it deviates from the meridian direction.
If the multi-hole diaphragm 4 is provided outside of the diaphragm 4, the refractive power in the three meridian directions can be calculated from the position of the projected light beam, and the refractive value including the degree of astigmatism can be calculated. In addition, the test lens L
The proportionality coefficient regarding the distance between
the distance between the apertures 4a, 40, the distance between the apertures 4b, 4c, and the direction along the optical axis 0]. It is given in advance depending on the distance between the optical position detectors 5.

When an image sensor such as a CCD is used as the optical position detector 5, the image on the image sensor may be processed as a video signal by a CPU or the like.

It should be noted that the position of the contact member 3 may be anywhere between the lens 2 and the multi-hole diaphragm 4, but it is preferable that it be located near the multi-hole diaphragm 4. Furthermore, instead of the multi-hole diaphragm 4, a diaphragm 4' having an annular opening 4a' as shown in FIG. The refractive power is calculated from the shape of the annular projection light beam.

FIG. 5 is a configuration diagram according to another embodiment, in which a lens 6 is arranged on the optical axis O1 between the contact member 3 and the multi-hole diaphragm 4. This embodiment has the advantage that the position of the projection light beam on the optical position detector 5 can be moved to an appropriate position using the lens 6.

[Effects of the Invention] As explained above, the lensmeter according to the present invention projects a parallel light beam onto the lens to be tested, and transmits the transmitted light beam through an aperture around the optical axis that allows distances between at least three meridian directions to be obtained. The light is received on the optical position detector located at a finite distance from the diaphragm through the diaphragm, and the refraction value is measured from the receiving position, so the light flux after passing through the diaphragm is No need to separate from the optical axis using a separating prism (
Therefore, it is possible to realize a simple configuration without providing a separation prism.

[Brief explanation of the drawing]

The drawings show an embodiment of the lens meter according to the present invention.
2 and 4 are front views of the aperture, FIG. 3 is a front view of the optical position detector, and FIG. 5 is a configuration diagram of another embodiment. Symbol l is a light source, 2.6 is a lens, 3 is a contact member, 4.4
° is an aperture, 5 is an optical position detector, circle is a television monitor, and L is a lens to be tested. Patent applicant Canon Co., Ltd. Figure 1

Claims (1)

[Scope of Claims] 1. A projection optical system that projects a parallel light beam onto a test lens, and an aperture having an aperture around an optical axis in at least three meridian directions for projecting a parallel light flux that has passed through the test lens. a light-receiving optical system that receives light on a two-dimensional optical position detector disposed at a position optically separated from the aperture by a finite distance; A lens meter that measures the refractive value of a lens to be tested. 2. The lens meter according to claim 1, wherein the output of the optical position detector is displayed on a television monitor.