JPS6052373B2 - Projection type foco for measuring the apex refractive power of a lens - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a projection focometer for measuring the magnification of a lens under test.

This consists of a casing and a movable cross-shaped test pattern,
a scale with a magnification scale movably connected to the test pattern, and first and second optical systems that respectively project images of the test pattern and the scale onto a screen having a fixed reference mark. , a device that supports the lens to be tested with its optical axis substantially aligned with the optical axis of the first optical system device, and an illumination device that includes a light source for illuminating the test pattern and the graduation scale, etc. It is. Projection focimeters of this type are well known in the art. For example, French patent no.
994,547. The casing of the projection folcometer described in the above-mentioned patent is of vertically extending configuration, so the overall height of the device is quite high.
Moreover, the projection screen is arranged vertically and the folocometer is placed on a fairly low table or bench.
Observing the screen is somewhat inconvenient because the operator performs the test while standing on the table. Accordingly, the current trend in the field of projection phocometers is to provide devices with screens tilted relative to the vertical in order to allow the phocometer to extend horizontally and facilitate observation. However, in this current trend of projection focometers, a single light source is used to illuminate the graduation scale and test pattern, making it impossible to place the light source close enough to the graduation scale and test pattern. It is. A light source is placed on one side, a graduation scale and a test pattern are placed on the other side, and a number of total reflection mirrors and at least one semi-transparent reflection mirror are placed between the two sides. Totally reflective mirrors and semi-transparent mirrors are relatively expensive components. On the other hand, since the test pattern is relatively far from the light source and its position changes, its illumination changes as a function of position. As a result, for a given location of the test pattern, the image appearing on the screen will be relatively light-resistant, making its observation somewhat difficult. The main objective of the invention is to eliminate these drawbacks with a new and useful lighting device.

To this end, the present invention generally provides a projection focimeter of the type described above, in which the illumination devices are placed together at one end and one at the other end adjacent to the graduation scale;
The other is two optical fibers placed adjacent to the test pattern and a condenser that focuses the light from the light source onto one end of the two optical fibers together. and an optical device. This arrangement allows most of the energy from the light source to be collected at the end where the two optical fibers meet, and to transmit the light energy to the graduation scale and test pattern with little loss.

Therefore, the graduation scale and test pattern can be brightly illuminated. Furthermore, the end of the optical fiber adjacent to the test pattern can be connected to the test pattern so as to move with the test pattern, so that the illumination of the test pattern can be made independent of changes in the position of the test pattern at that time. is possible. The invention will be described in detail in conjunction with the accompanying figures.

The projection type focometer illustrated in the figure has a casing 1
Inside, there is a cross-shaped movable test pattern 2, a scale 3 that is graduated in units of vertex refractive power and is provided to move together with the test pattern 2, and images of the test pattern 2 and the graduation scale 3 are displayed on a screen 4, respectively. first and second optical devices for projecting, a device 5 for supporting the lens under test 6 such that the optical axis of the lens 6 substantially coincides with the optical axis 7 of the first optical device, and a sight 2. It has an illumination device 8 for illuminating the graduation scale 3.

The test pattern and the graduation scale 3 are positioned in relation to each other, that is, as illustrated in FIG. A first optical device (e.g. a plurality of lenses 9,
10, 11, 12 and multiple mirrors 13, 14, 15, 16
) is adapted to form a sharp image of the test pattern 2 on the screen 4. The deasporometer 17 is arranged to allow measurement of the prism angle of the lens under test, if necessary, when the prism angle of the lens exceeds a predetermined value. The second optical device includes, for example, a prism 18 arranged in front of the graduation scale 3 and serving as a mirror;
It consists of a lens system 19, a mirror 20, and the mirror 16 described above.

When the scale 3 is in the position described above, the stationary prism 18 is located in front of the graduation line "0" of the graduation scale 3. As shown more particularly in FIG.
A scale is provided on a plate of a transparent material, for example by etching, and is fixed to a support 21 having an approximately inverted U-shape.

The support body 21 is slidably mounted on a pair of fixed guide rods 22, and the guide rods are connected to the optical axis of the lens device 19 and the lens 9,
It is parallel to the optical axis of 10. The support 21 is moved along a guide rod 22 by a rack 23, which is fixed to the support and meshes with a gear 24. It can be twisted and rotated. The handles are fixed to both ends of a shaft 26 to which a gear 24 is fixed. prism 18
and the lens system 19 are rigidly fixed to a fixing rod 27, which extends longitudinally into a groove formed between the arms of the inverted U-shaped support 21.

The cross-shaped test pattern 2 is a hollow test pattern support 2
Since the test pattern 2 is mounted inside the lens 8, the center of the test pattern 2 coincides with the optical axis 7 of the lenses 9 and 10.

The test pattern support 28 is slidably attached to a pair of guide bars 29 fixed in a space extending parallel to the guide bars 22 described above. In order to allow rotation of the test pattern 2 about the optical axis 7, the test pattern support 28 is also mounted for rotation about said axis.

For this purpose, the guide rod 29 is supported by a pair of rings 30, 31 at both ends of the rod. The ring is rotatably mounted on a socket 32 fixed to the casing 1, and its axis of rotation coincides with the optical axis 7.
A control ring 33 is rigidly secured to ring 31 for rotation of the apparatus including the pair of rings 30, 31, guide rod 29 and test pattern support 28.
The test pattern support 28 is connected to the inverted U-shaped support 21 and is movable together with the support 21 along guide rods 29 and 22.

For this purpose, the support body 28 has a circular groove 34 formed on its outer periphery, as shown in FIG. It is fixed to the support body 21. An opening 36 is formed in the socket 32 to allow movement of the tie rod 35 and its free movement during axial movement of the test pattern support 28. The lighting device 8 is, for example, a power source (not shown).
It includes a single light source 37 device of a light bulb powered by a light bulb.

In accordance with the present invention, optical energy from power source 37 is transferred to a pair of optical fibers 40, 41 by means of condensing optics 38.
The light is focused toward the end 39 where the two are brought together. A reflector in the bulb or separately may be arranged to reflect the energy of the light emitted behind the light source 37, ie in a direction opposite to the optical device 38, back to the optical device.
The other end 42 of the optical fiber 40 is placed adjacent to the graduation scale 3.

When the lens under test is not placed on the support device 5,
The other end of the optical fiber 40 is fixed so that the end face of the optical fiber 40 illuminates the "0" graduation line of the graduation scale 3 at a position where the sharp image of the test pattern 2 is projected onto the screen 4. The other end 43 of the fiber 41 is arranged adjacent to the test pattern 2, its end face aligned with the test pattern and able to move axially with the test pattern 2. For this purpose, the optical fiber 41 is It freely passes through an opening formed in the control cylinder 33 and is inserted into the hollow test pattern support 28. However, in order to prevent the optical fiber 41 from being twisted when the test pattern support 28 rotates, the test pattern is arranged such that it can be rotated relative to the support by the bearing 44. It is attached to a support 28.

With the above arrangement of illumination devices, the graduation scale 3 and the test pattern 2 can be brightly illuminated using a single light source of relatively moderate candlelight, regardless of the axial position of the test pattern.

This advantageous result is mainly due to the fact that the energy of the light source is
and 41, and the two optical fibers are arranged to ensure that the optical energy "key" is transferred such that the test pattern 2 and the graduation scale 3 are illuminated from their opposite ends 42 and 43. This is due to the fact.The operation of the above embodiment will be explained below.

As described above, with no lens 6 to be tested on the support device 5, the operating handle 25 is rotated to adjust the first optical system, and a sharp image of the test pattern 2 is formed on the screen 4. In this case, the zero scale of the graduation scale 3 is projected onto the fixed reference mark of the screen 4, as shown in FIG.

When the lens to be tested 6 is placed on the support device 5 in the above state, the image of the test pattern 2 on the screen 4 becomes blurred. In other words, the pits are shifted. In order to align the pits of the image of test pattern 2 on screen 4 soil, the operating handle 25 is rotated to adjust the first optical system. By directly reading the scale image of the graduation scale 3 projected onto the fixed reference mark on the screen 4 when an image with aligned pits is formed again, the diopter of the ν lens to be tested can be determined. When adjusting the movement of test pattern 2 above,
The other end of the optical fiber 40 that illuminates the test pattern 2 moves together with the test pattern 2, so the image of the test pattern 2 on the screen 4 during adjustment does not become brighter or darker and remains constant. Since this brightness can be obtained, pit adjustment can be performed very easily and reliably.

Furthermore, if the fixed reference mark is a vernier scale, it is possible to measure the diopters of the lens 6 to be tested with even higher accuracy.

[Brief explanation of the drawing]

FIG. 1 is a partially cut-away side elevational view of a projection focal length measuring instrument according to the present invention. FIG. 2 is a cross-sectional view taken along the line - of FIG. 1...
...Casing, 2...Test pattern,
3●●Scale, 4●●●●●●Screen, 511●
●Test lens support device, 6, 9, 10, 11, 12.
・Lens, 7... Optical axis, 8... Lighting device, 13, 14, 15, 16, 20... Mirror, 1
7... Deasporameter 1, 18... Prism, 19... Luns system, 21... Scale support, 22, 29... Guide rod, 23... ...
...Rack, 24...Gear, 25...Handle,
26... shaft, 27... fixed rod, 28...
・Test pattern support body, 30, 31...Ring, 32...Socket, 33...Control ring, 34...Circular groove, 35...Connection rod , 36
...Aperture, 37...Single light source, 38.
...Optical system, 39,42,43...Optical fiber terminal, 40,41...Optical fiber, 44...
·bearing.

Claims (1)

[Scope of Claims] 1. A projection type focometer for measuring the apex refractive power of a lens, comprising a movable test pattern, a graduation scale movably disposed integrally with the test pattern, a screen, and a movable test pattern. a first optical system that forms an image of the test pattern on the screen; a second optical system that projects a partial image of the scale of the graduation scale onto the screen; a support device for supporting the first optical system so as to be substantially aligned with the optical axis; and an illumination device for illuminating the test pattern including a light source and a portion of the graduation scale, the lens being tested not being present. In this case, the first optical system is adjusted so that a zero scale portion of the graduation scale is projected onto the screen at a position where a sharp image of the test pattern is formed on the screen. In the projection folcometer, the illumination device further comprises two optical fibers, one end of which is bundled together and the other end of which is disposed adjacent to the test pattern and the graduation scale, respectively; The fiber has a condensing optical system that condenses light from the light source on one end of the bundled spring, and the end of the fiber adjacent to the test pattern is movable together with the test pattern. Fuocometer. 2. The fociometer according to claim 1, wherein the test pattern is centered on the optical axis of the first optical system, and the test pattern is mounted in a hollow test pattern support. and the end of the other optical fiber adjacent to the test pattern is placed on the test pattern support such that it is not possible to move relative to it, but it is not possible to rotate it relative to it. A focometer characterized by being fixed in place.