JPS59147236A - Lens eccentricity measuring apparatus - Google Patents

Abstract

PURPOSE:To contrive to enhance measuring preciseness, by electrically detecting the eccentric amount of a lens to be measured or a lens system by maniplying the same. CONSTITUTION:The laser beam from a laser oscillator 10 is reflected by a reflex mirror 11 and a lens 14 to be inspected is provided to the beam path of the reflected beam so that said beam is vertically incident to the surface of the lens 14 to be inspected in aligned relation to the beam axis. The beam permeated through the lens 14 is refracted by a prism 12 and received by a light receiving apparatus 12 while emitted to the direction different from the incident direction to detect an incident position. As the light receiving apparatus, CCD is suitable and, by precisely measuring the deviation of the incident positions of the laser beam to the light receiving apparatus when the lens 14 to be inspected is present and absent while converting each of said incident positions to the quantity of electricity, the eccentric amount of the lens to be inspected can be calculated with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a device for measuring optical axis eccentricity of an optical lens or lens system.

Decentering of an optical lens or lens system causes a decrease in the accuracy of various devices having an optical system. Therefore, efforts are being made to eliminate the eccentricity that occurs during lens processing and lens system assembly. A collimator has conventionally been used to measure the eccentricity of this lens and lens system. Measurement of eccentricity of a lens or lens system using a collimator is performed using a light source 1 as shown in FIG.
The light rays emitted from the glass illuminate the signboard 3 through the condensing lens 2,
The collimator lens 4 converts the light into parallel light beams, and the light beams enter the lens 5 to be examined. The lens 5 to be tested is installed perpendicular to the optical axis, and the light beam is focused at the focal point 6 of the lens 5 to be tested to form a target image. The microscope 7 is adjusted along the optical axis so that this image can be observed and seen using the microscope 7. Next, the lens 5 to be tested is rotated to move the image 6 and the amount of movement thereof is measured.

When this amount of movement is l and the focal length of the lens 5 to be tested is f, the eccentricity S is determined by reading the angle using the formula S=t/2f.

In this method, it is difficult to measure eccentricity with high accuracy because the amount of movement t of the image is small compared to the lens focal length f. In particular, for objects with short focal lengths, the displacement to be measured is small and accuracy cannot be obtained by observation with a microscope.◎ Jn This invention addresses the above-mentioned situation of accuracy in measuring eccentricity of lenses and lens systems using conventional collimators. In view of this, it is an object of the present invention to provide a lens eccentricity measuring device that can improve measurement accuracy.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to drawings showing embodiments thereof.

FIG. 2 shows an embodiment of the present invention, in which a laser oscillator 10 as a measurement light source, a reflecting mirror 11, a prism 12, and a light receiving device 13 are arranged in the optical path of the laser i beam. has been done. A laser beam generated by a laser oscillator 10 is reflected by a reflecting mirror 11, and a test lens (or lens system) 14 is placed in the optical path of the reflected light beam so that the light beam is perpendicular to the surface of the test lens 14 and coincides with the optical axis. It is installed so that it is incident. The light beam transmitted through the test lens 14 is refracted by the prism 12 and emitted in a direction different from the direction of incidence. This emitted light beam is received by the light receiving device 12, and the position of incidence on the light receiving device is detected.

For example, a CCp or the like is suitable as the light receiving device.
By accurately measuring the deviation of the incident position of the laser beam onto the light receiving device in the case where 4 is not present, the amount of eccentricity of the lens to be tested can be determined with high precision.

The principle will be explained in detail below.

FIG. 3 schematically shows the optical path of the laser beam in the vicinity of the test lens 14, prism 12, and light receiving unit 13 of the eccentricity measuring device of the present invention. If there is no
It enters the surface 12a at the KA point, is refracted and becomes the second surface 12b.
is emitted from point 0 and enters the light receiving section +1i13 (7q plane) at point E.

- A laser beam emitted from the lens to be tested with force and eccentricity (angle) ε enters the first surface 12aKB point of the prism 12, is refracted, exits from the second surface 12b at the 0 point, is refracted, and is refracted into the light receiving device 13. is incident on the surface at point F.

Now, in FIG. 4, the apex angle of the prism 12 is α, the incident angle of a certain ray on the first surface is θ, and the refraction angle after incidence is θ.
1', the incident angle to the second surface is 02', and the exit angle is θ2. According to Suille's law, sin θ, = n s
in θ(-・・-(1) sin θ2 ”n8inθ
2' (2) where n is the refractive index of the prism with respect to air.

, -1sinθ1 From equation (1), θ,'= Sin () =・
・(3) In Figure 4, the point of incidence of the ray on the first surface is set to 0.
1 The exit point from the second surface is H1, the vertex of the prism is 1, and the intersection of the perpendicular lines erected at point G and point 1 on the first surface and Figure 2, respectively, is J.
Then, OtsuHGJ−θ,', 1GHJ=θ2/, 1GIH
-α1IGJ=LR, LIHJ=lR 1, θ,'+θ'=α -0,02'”' ct ++ 01'
・・・・・・(4) Substituting equation (4) into equation (2), sin θt=n sin Substituting equation (3) into (a-θ,′),′, θ2= sin”-1(n 5in(α-8i, T
Since the apex angle α and the refraction in of the I (Bin-θ′) )·f61 prism are constant, θ2 can be determined from 7θ1.

Next, the incident angle θ1 has an angular difference between θ1 and ε. If the exit angle from the second surface of the ray incident on the first surface of this prism is 021, then from equation (6), θ, 1=sin-'(n 5in(α-5in-'(self) )]...(7) The angular difference between the incident angles θ1 and θ1. is ε
Therefore, 0 ε + θ.

Here, if 01 is the angle of incidence on the prism without the above-mentioned inspection lens, ε corresponds to the eccentricity (angle) of the above-mentioned lens.

Substituting θ = θ −ε into equation (7), we get 11
1 θ21 = sinl (n 5in(α−5ir(””
'-'))]...(s). Therefore, equation (6) and (8
) From the formula, 15in”(n s in[α-s 1nH-'(m'
) ) ] θ, −021=δ, the relationship between δ and ε is from the above equation, and if δ is known, ε can be found.

When the angle of incidence 01 is made small, equation (5), that is, sin θ
2=n 5in (α-s in-' (self) θ2 becomes larger than 1.

Therefore, if the relationship between θ and ε is similarly determined by reducing 01, the ratio between 6 and δ will also become smaller, and a higher precision can be obtained by expanding the value of ε.

By providing two prisms between the lens to be tested and the light receiving device, measurements can be made with greater magnification than the eccentricity of the lens to be tested.

Further, as shown in FIG. 5, the first surface 15a of the prism 15
If the surface 15b facing the surface 15b is made a mirror and the light is emitted from the first surface 15a, the emission angle θ2 can be increased. Furthermore, as shown in FIG. 6, by using two of these mirrored prisms 15, it is possible to further increase the exit angle θ2.

Depending on the necessity of the arrangement of the apparatus, it is also possible to provide a reflecting mirror 16 between the lens to be examined 14 and the prism 14, as shown in FIG.

Effects As described above, according to the present invention, the amount of eccentricity of the lens or lens system to be measured can be expanded and electrically precisely measured, which is effective in improving the performance of equipment using optical systems.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of a conventional lens eccentricity measuring device, FIG. 2 is a sectional view showing an embodiment of the present invention, and FIG. 3 is a diagram showing the optical path after the test lens of the device of the present invention. 4 are schematic diagrams for explaining the present invention in detail, and FIGS. 5 to 7 are sectional views showing the peripheral portions of prisms of other embodiments of the present invention. 10... Laser oscillator

Claims (1)

[Claims] It has a laser oscillator, a prism provided in the optical path of the laser beam emitted from the laser oscillator, and a light receiving device, such that the laser beam is incident perpendicularly to the surface of the optical lens or lens system to be measured and coincident with the optical axis. An optical lens or lens system to be measured is installed, a laser beam that has passed through it is made incident on a prism, and the light receiving device detects the position of incidence of the emitted light beam on the above-mentioned light receiving device. 1. A lens eccentricity measuring device, characterized in that the optical axis eccentricity of a test optical lens or lens system is measured from the deviation from the position when the optical lens is not in use.