JPH0339625B2 - - Google Patents
Info
- Publication number
- JPH0339625B2 JPH0339625B2 JP59104111A JP10411184A JPH0339625B2 JP H0339625 B2 JPH0339625 B2 JP H0339625B2 JP 59104111 A JP59104111 A JP 59104111A JP 10411184 A JP10411184 A JP 10411184A JP H0339625 B2 JPH0339625 B2 JP H0339625B2
- Authority
- JP
- Japan
- Prior art keywords
- grating
- lens
- focal length
- tested
- moiré fringes
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M11/00—Testing of optical apparatus; Testing structures by optical methods not otherwise provided for
- G01M11/02—Testing optical properties
- G01M11/0228—Testing optical properties by measuring refractive power
Landscapes
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Testing Of Optical Devices Or Fibers (AREA)
Description
【発明の詳細な説明】
この発明はモアレ縞によるレンズの焦点距離
（あるいは屈折力）の測定法に関するものである。
本発明の特徴は、被検レンズの焦点距離を簡単な
装置で容易に迅速かつ精度良く測定できることで
ある。レンズの焦点距離は、主点から焦点までの
距離であり、焦点は平行光線の収束点として容易
に見出し得るが、主点は直接見出し難いものであ
る。従来からのレンズの焦点距離測定法には、ノ
ーダルスライド法、ベツセル法、および倍率によ
る方法などがあるが、これらの方法では、測定装
置の長さが少なくとも被検レンズの焦点距離以上
必要であるという欠点がある。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for measuring the focal length (or refractive power) of a lens using moiré fringes.
A feature of the present invention is that the focal length of a lens to be tested can be easily, quickly, and accurately measured using a simple device. The focal length of a lens is the distance from the principal point to the focal point.The focal point can be easily found as the convergence point of parallel rays, but the principal point is difficult to find directly. Conventional lens focal length measurement methods include the nodal slide method, the Bessel method, and the magnification method, but these methods require the length of the measuring device to be at least longer than the focal length of the lens being tested. There is a drawback.
本発明は、被検レンズを透過した光波がさらに
その直後におかれたピツチの等しく格子線の方向
がたがいにわずかに異なる一対の格子板を透過す
るとき、形成されるモアレ縞の傾き角が被検レン
ズの焦点距離に依存することに着目したものであ
る。すなわち、被検レンズを透過した光波で第１
の格子を照射し、これによつて生じた格子のフー
リエ像と、この像面上におかれた第２の格子とに
より観測されるモアレ縞の傾き角からレンズの焦
点距離を求めるものである。 In the present invention, when a light wave transmitted through a test lens is further transmitted through a pair of grating plates placed immediately after the same pitch and whose grating lines are slightly different in direction, the inclination angle of the moiré fringes formed is This method focuses on the dependence on the focal length of the lens to be tested. In other words, the first light wave transmitted through the test lens
The focal length of the lens is determined from the Fourier image of the resulting grating and the inclination angle of the moiré fringes observed by the second grating placed on the image plane. .
第１図は本発明による焦点距離測定法の原理図
である。被検レンズ１の光軸をＺ、第１の格子を
２、また第２の格子を３とする。波長λの平行平
面波を被検レンズ１に入射し、透過した光波をピ
ツチｐの第１の格子２に照射すると、この格子か
らおよそZo＝2np2／λおよびnp2／λ（ｎは正の整
数）の位置に第１の格子２と同じ周期構造を持つ
フーリエ像およびネガテイブフーリエ像をつく
る。このフーリエ像面上に、第１の格子２の格子
線に対して相対的にわずかにθだけ傾けて第２の
格子３を配置すると、第１の格子２のフーリエ像
と第２の格子３とで傾いたモアレ縞を生じ、この
傾き角αから直ちにレンズの焦点距離が求められ
る。このモアレ縞の傾き角αとレンズの焦点距離
ｆとの関係は、
ｆ＝Zo（tanα sinθ＋cosθ）／tanα sinθ＋cos
θ−１
で与えられる。また屈折力Ｄで表わすと、
Ｄ＝１／ｆ＝１／Zo（１−１／tanα sinθ＋cosθ
）
と書ける。したがつて、モアレ縞の傾き角αを測
定すれば上式より直ちにレンズの焦点距離ｆまた
は屈折力Ｄが求められる。 FIG. 1 is a diagram showing the principle of the focal length measurement method according to the present invention. It is assumed that the optical axis of the lens 1 to be tested is Z, the first grating is 2, and the second grating is 3. When a parallel plane wave of wavelength λ is incident on the test lens 1 and the transmitted light wave is irradiated onto the first grating 2 of pitch p, from this grating approximately Z o = 2np 2 /λ and np 2 /λ (n is positive A Fourier image and a negative Fourier image having the same periodic structure as the first grating 2 are created at the positions (an integer of ). When the second grating 3 is placed on this Fourier image plane at a slight angle of θ relative to the grating lines of the first grating 2, the Fourier image of the first grating 2 and the second grating 3 are This produces tilted moiré fringes, and the focal length of the lens can be immediately determined from this tilt angle α. The relationship between the tilt angle α of this moire fringe and the focal length f of the lens is f=Z o (tanα sinθ+cosθ)/tanα sinθ+cos
It is given by θ−1. Also, when expressed in terms of refractive power D, D=1/f=1/Z o (1-1/tanα sinθ+cosθ
) can be written as Therefore, by measuring the inclination angle α of the moiré fringes, the focal length f or refractive power D of the lens can be immediately determined from the above equation.
以上のように、２枚の格子板の間隔Zoおよび互
の格子線のわずかな相対角度θを固定しておけ
ば、モアレ縞の傾き角度αを測定することにより
上式から直ちにレンズの焦点距離ｆまたは屈折力
Ｄが求まる。 As described above, if the interval Z o between the two grating plates and the slight relative angle θ between the grating lines are fixed, then by measuring the inclination angle α of the moiré fringes, the focus of the lens can be determined directly from the above equation. The distance f or the refractive power D is determined.
本発明の特長は、
１ ２枚の格子板を適当な間隔をおいて配置した
ものが主要部分であるから、測定装置の長さを
短かくできる。特に、長焦点レンズの測定に有
効である。例えば、格子ピツチｐ＝0.2mm、波
長λ＝500nmの光波を用いた場合、Zo=1＝80mm
程度である。 The features of the present invention are as follows: 1. Since the main part consists of 2 grid plates arranged at appropriate intervals, the length of the measuring device can be shortened. It is particularly effective for measuring long focal length lenses. For example, when using a light wave with grating pitch p = 0.2 mm and wavelength λ = 500 nm, Z o = 1 = 80 mm.
That's about it.
２ 被検レンズの全開口で連続して測定が可能で
ある。例えば、２重焦点眼鏡レンズの測定も可
能である。2. Continuous measurement is possible with the full aperture of the lens to be tested. For example, it is also possible to measure bifocal eyeglass lenses.
３ 第２の格子が第１の格子のフーリエ像面に置
かれているのでコントラストの良好なモアレ縞
が得られる。3. Since the second grating is placed on the Fourier image plane of the first grating, moiré fringes with good contrast can be obtained.
４ 光源として、レーザー光を用いなくても白色
光源と色フイルターの組み合わせで測定が可能
である。4. Measurement can be performed using a combination of a white light source and a color filter without using a laser beam as a light source.
図は本発明の方法を実施する場合の原理図を示
すものである。
１……被検レンズ、２……第１の格子板、３…
…第２の格子板、Ｚ……被検レンズの光軸、Zo…
…２枚の格子板の間隔、ｆ……被検レンズの焦点
距離、Ｆ……被検レンズの焦点。
The figure shows a principle diagram when implementing the method of the present invention. 1...Test lens, 2...First grating plate, 3...
...Second grating plate, Z...Optical axis of test lens, Z o ...
... Distance between two grating plates, f... Focal length of the test lens, F... Focus of the test lens.
Claims (1)
子板を被検レンズの直後に配置し、平行光束を入
射してモアレ縞を発生させ、この縞の傾きから被
検レンズの焦点距離を測定する方法。1 Place a pair of grating plates with an appropriate spacing and equal pitch immediately behind the lens to be tested, generate moiré fringes by injecting a parallel beam of light, and measure the focal length of the lens to be tested from the inclination of these fringes. how to.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10411184A JPS60247133A (en) | 1984-05-22 | 1984-05-22 | Focal-length measuring method of lens by using moire fringe |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10411184A JPS60247133A (en) | 1984-05-22 | 1984-05-22 | Focal-length measuring method of lens by using moire fringe |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS60247133A JPS60247133A (en) | 1985-12-06 |
| JPH0339625B2 true JPH0339625B2 (en) | 1991-06-14 |
Family
ID=14372014
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10411184A Granted JPS60247133A (en) | 1984-05-22 | 1984-05-22 | Focal-length measuring method of lens by using moire fringe |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS60247133A (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6771362B2 (en) * | 2001-12-27 | 2004-08-03 | Rotlex Ltd. | Method and apparatus for testing and mapping phase objects |
| JP4539650B2 (en) | 2006-12-26 | 2010-09-08 | セイコーエプソン株式会社 | Optical characteristic evaluation method for optical system, optical characteristic evaluation method for projector, optical characteristic evaluation apparatus, and screen |
| CN102252824B (en) * | 2011-04-12 | 2013-03-27 | 浙江大学 | Compound differential type long-focus measuring device based on Talbot effect |
| CN107515103B (en) * | 2016-06-17 | 2019-06-21 | 南京理工大学 | A focus detection device and method using ring grating |
| CN109799078B (en) * | 2019-03-08 | 2020-05-15 | 中国科学院长春光学精密机械与物理研究所 | A device and method for measuring the focal length of a collimator by using moire fringe magnification |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5816216A (en) * | 1981-07-22 | 1983-01-29 | Canon Inc | talbot interferometer |
-
1984
- 1984-05-22 JP JP10411184A patent/JPS60247133A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS60247133A (en) | 1985-12-06 |
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