JPS60236043A - Device for inspecting eccentricity - Google Patents

Abstract

PURPOSE:To measure automatically with good accuracy the eccentricity of a lens by moving a grid by the same quantity of the deflection of the outer peripheral part with rotation of a lens to be detected and by counting the number of spotted images passing through the transparent part of the grid with detection. CONSTITUTION:A lens 12 to be detected is set up on a rotating unit 11 and rotated. The spotted image by the lens 12 is rotated under the condition of adding the eccentricity due to rotation and the eccentricity of the lens itself. The deflection of the outer peripheral part of the lens 12 is measured by a noncontacting displacement gage 13 and a grid 14 is moved in accordance with the displacement of the outer peripheral part by an electro-distorting element 15. The rotation of the spotted image is thus caused only by the eccentric component of the lens 12 and the eccentricity can be measured by detecting the spotted images passing through the transparent part of the grid 14 with a photoelectric transducer 17 and by counting the number of the times with a counter 18.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an eccentricity testing device for measuring the eccentricity of a 1-i lens.

Conventional configuration and its problems One of the reasons for the deterioration of the +1 power of the lens system is the eccentricity of the lens. When an eccentric lens is assembled into a casting barrel,
The inclination of the lens or the V lens ('M - t': f
1, etc. occur, and the coaxial ze 1 of the lens system takes precedence. 1 As a result, coma aberration occurs even on the axis 3,! For lens systems with diffraction limited systems such as i5 microscope objective lenses and recent pink-up lenses for digital audio, it is accepted that the eccentricity tolerance is strict, and the eccentricity 11111 formula for a highly accurate lens is accepted. '7J4 sleeping.

Referring to the drawing below, the eccentricity of the lens iI! ll'r
j! The principle of , will be explained. FIG. 1 is a principle diagram of the eccentric side 5'P of the lens. Reference numeral 1 indicates a lens to be tested, 2 indicates an optical axis of the lens, and 3 indicates a central axis of a cylinder determined by the outer circumference or edge of the lens to be tested 1, which is hereinafter referred to as the central axis of the lens. 4 is a parallel light beam, and 6 is a spot image created by the lens 1 to be examined. In a lens without eccentricity, the optical axis 2 and the central axis 3 of the lens coincide.

When a parallel light beam 4 is made incident on the lens 1 to be tested, a spot image 6 is formed on the optical axis 2 of the lens. Here, the test lens 1 is rotated around its central axis 3. In a lens without eccentricity, the optical axis 2 and the central axis 3 of the lens coincide, so the spot image does not rotate.

However, if there is a deviation of a distance d between the round shaft 2 and the central axis 3, the spot image 6 rotates in a circle with a radius d. The amount of eccentricity can be measured by measuring the radius of rotation of the spot image 6 when the lens is rotated around its central axis 3.

A conventional eccentricity testing device will be described below with reference to the drawings. Figure 2 is a conceptual diagram of a conventional eccentricity testing device.
Reference numeral 6 denotes a collimator, 7 a lens holder, 8 test lenses, and 9 a microscope for observing a spot image produced by the test lens 8.

The operation of the eccentricity testing device configured as described above will be described below. The parallel light emitted from the collimator 6 enters the lens 8 to be tested. Then, when the spot image converged by the test lens 8 is rotated with a finger, for example, in the lens holder 7 while viewing the spot image converged by the test lens 8 with a microscope, if the test lens 8 is eccentric, the eccentricity d is taken as the radius. The spot images rotate at the same time. /(Ga-, the lever rotator i'f is l/I'i1" Le1:, C+ is read, and the eccentricity of the lens 4IIll'+i: l, 71
．． 1 However, I-, ii myself) 1 Niwa na + i'f
ll'l: ni1.・It is 11, -? if M lens 8
Since it is necessary to rotate within the lens holder 7, there is naturally a gap between the lens 8 to be tested and the lens holder 7. It was necessary to rotate the lens while pressing it to one side with L7'e -).For a lens with strict eccentricity tolerance such as 3,'+, for example, a flid of 6 μm f11 degrees. There is a case where the center 1a is set to all 1a, and in the conventional N11l'+i- method (, shi, shield jO is set to [1-b).

OBJECTS OF THE INVENTION It is an object of the present invention to provide an eccentricity testing device rt that accurately and automatically measures the eccentricity i11 of e-luns.

Composition of the Invention The eccentricity testing device IT of the present invention provides a test lens with: 1: a light source for creating a respot image; a rotation device that rotates the test lens 6 approximately around its optical axis; 1) Item 11. 'f'12
1l II of the first lap of the evening due to the rotation of the detection lens.
I5: [J゛66 page] A displacement meter, a grating located on the image plane of the test lens and consisting of a transparent part and an opaque part, and a vibration caused by the rotation of the test lens according to the output of the displacement meter. and a counting means for counting the number of gratings through which the smeared image passes as the subject lens rotates. , thereby measuring the amount of eccentricity of the lens.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 is a schematic diagram of an eccentricity testing device according to an embodiment of the present invention. In FIG. 3, 1o is a light source, 11 is a rotating device for rotating the test lens 12, and 13 is a test lens 12.
A non-contact displacement meter 14 is a grid consisting of a transparent part and an opaque part located on a spot converged by the test lens 12, and chromium is vapor-deposited on a glass plate. use something 16 is an electrostrictive element for moving the grating 14 in a direction perpendicular to the 1st rotation axis of the rotating device 11;
18 is a counter that counts the number of pulses of light incident on the photoelectric conversion element 17 (17). Rotating device 1 rotates test lens 12
Place it on top of 1 and rotate it. The center axis of the test lens 12 and H
The rotation axis V1 of the transfer gap 11 and the test lens 12 are simply 1 []
It does not match 11 in general even if it is installed in 1-transfer device 11-
In addition, if a bearing is used in the rotating device 11, the rotation device 11 will have an eccentricity due to rotation of several microns or more. Its own eccentricity is added to J and it rotates in the state. In order to extract the eccentric component of only the test lens 12 from the rotation of this spot image, the test lens 1
The deflection of the outer periphery of 2 is measured using a non-contact displacement sensor 13. The output of the displacement meter 13 is amplified by the amplifier 16, and the electrostrictive element 1
6 to move the grating 14. By appropriately selecting the amplification factor of the amplifier 16.

Therefore, the amount of displacement of the outer peripheral portion of the lens 12 to be tested and the amount of movement of the grating 14 can be matched. In other words, these 7 pages.

The positional relationship between the failure inspection lens 12 and the grating 14 at this time is the same as the positional relationship between the test lens 8 and the microscope 9, which are pressed against one side of the lens holder 7 and rotated at the same time, in a conventional eccentricity inspection device. Therefore, the rotation of the spot image when viewed from the grating 14 (1) is due only to the decentering component of the test lens 12. It is assumed that the test lens 12 has a set of transparent and opaque parts.If the eccentricity of the test lens 12 is 5 μm, the spot image rotates on the grating 14 while drawing a circle with a radius of 6 μm.Therefore, the test lens 12 rotates once. This means that the spot image passes through the transparent portion on the grating 14 20 times.The photoelectric conversion element 17 detects the spot image each time it passes through the transparent portion, and the number of times is counted by the counter 18. If the condition is met, the number of counts when the test lens 12 rotates once is 20.
If so, it can be determined that the eccentricity is 5 μm. There is no harm in going up. The area corresponding to the eccentric shell of the f141F handling test 1/ns is a private sergeant, and it's a power train! Young Motoko 17, subo, 1, all shadows of the image, 1 for shi
A large light-receiving area is also required for ←, ro 1゜Efficacy of the invention W It is clear from the explanation below that l: uni, ], the invention (1,
When measuring eccentricity by rotating the cavity inspection lens to obtain a spot image on each side, the lens to be inspected is rotated 1. ft7 n, 5
On the evening of the same day, while measuring the deflection of the first rotation part,
) by moving the grid by the same amount as -, Tespo, 1.
From the movement of the image, the eccentricity of the lens under test is calculated by 1 Jk.
Take-out 12, transparent part 4-uraj of lattice r by photoelectric conversion element
lF,! Since the configuration 1° is configured to detect L/ζ-spot images and count the number thereof, the effect 9L that the eccentricity 16 of the lens can be easily and automatically measured is (i) r, r hru,.

[Brief explanation of drawings]

Figure 1 shows lens eccentricity measurement 11; Kosaizu with r,
FIG. 2 is a schematic view of the concept of a conventional eccentricity testing device, and FIG. 3 is a schematic diagram of a flit cardiac testing device in an embodiment of the present invention. 9pe1/1o...Light source, 11...Rotating device, 12...
...Test lens, 13...Non-contact displacement side, 14...
- Lattice, 16... Electrostrictive element, 16... Amplifier, 17... Photoelectric conversion element, 18 Counter. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 4゜1 11 5'1) / \ /N\ /11\ Figure 2 Figure 3

Claims (1)

[Claims] a light source for creating a spot image with the lens to be tested; a rotation device for rotating the lens to be tested about its optical path axis;
a displacement meter for measuring the deflection of the outer circumferential portion of the lens to be tested as it rotates; a grating that is located on the image plane of the lens to be tested and is made up of a transparent part and an opaque part; A moving means for moving the grating so as to cancel the wobbling caused by the rotation of the test lens, and a counting means for counting the number of the gratings through which the spot image passes as the test lens rotates. An eccentricity testing device characterized by: