JPS599537A - Method for measuring mtf - Google Patents
Method for measuring mtfInfo
- Publication number
- JPS599537A JPS599537A JP11688582A JP11688582A JPS599537A JP S599537 A JPS599537 A JP S599537A JP 11688582 A JP11688582 A JP 11688582A JP 11688582 A JP11688582 A JP 11688582A JP S599537 A JPS599537 A JP S599537A
- Authority
- JP
- Japan
- Prior art keywords
- line image
- intensity distribution
- mtf
- lens
- measuring
- 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.)
- Pending
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
- G01M11/0292—Testing optical properties of objectives by measuring the optical modulation transfer function
Landscapes
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Image Analysis (AREA)
Abstract
(57)【要約】本公報は電子出願前の出願データであるた
め要約のデータは記録されません。(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.
Description
【発明の詳細な説明】
この発明は、レンズ等の光学系のＭＴＦ測定方法に関す
る。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for measuring MTF of an optical system such as a lens.
レンズの性能の指標として用いられるＭＴＦ（Ｍｏｄｕ
ｌａｔｉｏｎ ｔｒａｎｓｆｅｒ ｆｕｎｃｔｉｏｎ、
コントラスト伝達率、レスポンス関数とも云う）の測定
は、テストチャートに例えばスリットとして設けられた
線状パターンを被検レンズで結像させ、得られた線像の
光強度分布をフーリエ変換することによって行なわれ、
測定されたＭＴＦ値をあらかじめ定められた規格値と比
較してレンズの良否を判定する。MTF (Modu) is used as an index of lens performance.
ration transfer function,
The contrast transfer rate (also referred to as response function) is measured by imaging a linear pattern provided as a slit on a test chart with a test lens and Fourier transforming the light intensity distribution of the obtained line image. Re,
The measured MTF value is compared with a predetermined standard value to determine the quality of the lens.
ＭＴＦ測定機の基本的な構成を第１図により説明すると
、光源ランプ１によりスリット２を形成したテストチャ
ート６を照明し、スリット２の透過光、すなわち線状パ
ターンの出射光を被検レンズ４により結像面５に結像さ
せ、得られた線像の光強度分布を線像と直角方向に設け
た受光素子アレイ（広く云えば電荷結合素子（ｃｈａｒ
ｇｅ ｃｏｕｐｌｅｄｄｅｖｉｃｅ ）以下ＣＣＤと略
す）６で検出し、その信号をコンピュータ７に入力して
フーリエ変換演算を行ない、ＭＴＦを求める。The basic configuration of the MTF measuring machine will be explained with reference to FIG. 1. A test chart 6 in which a slit 2 is formed is illuminated by a light source lamp 1, and the transmitted light of the slit 2, that is, the emitted light in a linear pattern is transmitted to a test lens 4. The light intensity distribution of the obtained line image is formed on the imaging plane 5 by a light receiving element array (broadly speaking, a charge-coupled device (char)
ge coupled device) (hereinafter abbreviated as CCD) 6, the signal is input to a computer 7, where a Fourier transform operation is performed to obtain the MTF.
スリット２はレンズの種々の像高位置、アジマス方向に
ついて複数本テストチャート６上に設けられ、結像面５
にはこれらのスリット２の各線像に対して夫々直交する
如くｃｃＤアレイ６が対応して設けられる。第２図はテ
ストチャート５の−例で、１１月１１」二及び周辺部４
個所計５個所に半径方向及び円周方向のスリット２が設
けられ、結像面５には第６図に示す如く、これに対応す
る位置にＣＣＤアレイ６が設けられている。A plurality of slits 2 are provided on the test chart 6 at various image height positions and azimuth directions of the lens.
A CCD array 6 is provided in correspondence with each line image of these slits 2 so as to be orthogonal to each line image. Figure 2 is an example of test chart 5, November 11''2 and peripheral portion 4.
Radial and circumferential slits 2 are provided at a total of five locations, and CCD arrays 6 are provided at corresponding positions on the imaging plane 5, as shown in FIG.
上記のＭＴＦ値の測定に際しては、ノイズ除去のために
、同一の線像を複数回繰返してＣＣＴ）アレイにより走
査して強度分布を読取り、各部毎に強度を平均化し、平
均化された強度分布を用いて演算処理を行なうことが従
来より行なわれている。When measuring the above MTF value, in order to remove noise, the same line image is repeated multiple times and scanned with a CCT) array to read the intensity distribution, the intensity is averaged for each part, and the averaged intensity distribution is It has been conventional practice to perform arithmetic processing using .
その場合、従来のＭＴＦ測定方法では、あるＣＣＤアレ
イの同一サンプル点のデータ同志を複数回加算し、加算
された後の線像強度分布についてピーク付近をコンピュ
ーターに転送し演算処理してＭＴＦ値を求めるのが通常
であった。しかし、この方法で線像強度分布の平均化を
行なった場合は、複数回のデータ読取り期間中に機械的
な振動等の原因で線像の結像位箇が変動し、ピーク位置
、すなわち位相がｒ−７′、いにずれることがしばしば
ある。In that case, in the conventional MTF measurement method, the data of the same sample point of a certain CCD array is added multiple times, and the area around the peak of the line image intensity distribution after the addition is transferred to a computer and processed to calculate the MTF value. It was normal to ask. However, when averaging the line image intensity distribution using this method, the position of the line image may vary due to mechanical vibrations or other causes during multiple data reading periods, and the peak position or phase is often shifted by r-7'.
したがって、この方法で加算又は平均化された線像強度
分布は、ゆらぎのノイズを拾うことになるので真の形状
よりもダした、即ちピーク値が低く尖鋭度の低い分布に
なり、正しいＭＴＦの値が得られないことになる。Therefore, the line image intensity distribution added or averaged using this method picks up fluctuation noise, resulting in a distribution with a lower peak value and less sharpness than the true shape, and the correct MTF. No value will be obtained.
この発明は、ノイズ除去のための線像強度分布の平均化
を−１−記の方法で行なう従来のＭＴＦ測定方法の」二
連の欠点にかんがみ、線像におけるノイズを除去するた
めの平均化により強度分布がダレるようなことがなく、
正しい強度分布が得られ、正確なＭ Ｔ ’Ｆ値を求め
ることが出来るＭＴＦ測定方法を提供することを目的と
する。In view of the two drawbacks of the conventional MTF measurement method in which the averaging of the line image intensity distribution for noise removal is performed by the method described in -1-, the present invention has been proposed to perform averaging for removing noise in line images. This prevents the intensity distribution from becoming distorted.
It is an object of the present invention to provide an MTF measurement method that can obtain a correct intensity distribution and determine an accurate M T 'F value.
以下、本発明をその実施例を示す図面にもとすいて詳細
に説明する。Hereinafter, the present invention will be explained in detail with reference to drawings showing embodiments thereof.
第４図において、多数のＣＣＤアレイ６がらの信号のう
ちの１つの信号がマルチプレクス（ＭＰＸ）８によって
選択され、アナログ・ディジタルコンバータ（ＡＤＣ）
９によりＡ／Ｄ変換され、ランダムアクセスメモリ（Ｒ
ＡＭ）１０に取り込まれる。In FIG. 4, one signal from a number of CCD arrays 6 is selected by a multiplexer (MPX) 8, and an analog-to-digital converter (ADC)
9, A/D conversion is performed by random access memory (R
AM) taken in at 10.
１つのＣＣＤアレイ６がらのデータ取込み回数を例えば
３回とすれば、メモリ（ＲＡＭ）１０には、第５図に示
す如く３個の線像データ■、■。If the number of times data is taken in from one CCD array 6 is, for example, three times, the memory (RAM) 10 stores three line image data (1) and (2) as shown in FIG.
■が取込まれる。■ is taken in.
このメモリから最初の１個の線像データ■を取出しくス
テップ■）、補正回路１１によりＣＣＤビットニおける
感度、暗電流のバラツキについて補正を行なう（ステッ
プ■）。次にＭａｙルーチン１２において線像強度分布
の最大値を探し出し、最大値のメモリのアドレスの前後
一定数のメモリだけを加算回路１３にストアする。残り
２個の線像データ■、■についても同様の処理を行ない
、加算回路１３にストアする。The first line image data (2) is retrieved from this memory (step (2)), and the correction circuit 11 corrects variations in sensitivity and dark current in the CCD bits (step (2)). Next, in the May routine 12, the maximum value of the line image intensity distribution is found, and only a certain number of memories before and after the address of the maximum value memory are stored in the adding circuit 13. Similar processing is performed on the remaining two line image data (2) and (2) and stored in the adder circuit 13.
加算回路１３からは、最大値の位置を合せた、換言すれ
ば位相の揃った６個の線像強度分布の和、あるいは平均
値が出力される。しため１って線像のゆらぎによる影響
は除去され、正確な、被検レンズのみによる線像強度分
布を得ることができ、これを用いてコンピュータ７によ
りフーリエ変換の演算を行なうことにより精度の高いＭ
ＴＦを測定することが可能となる。The adder circuit 13 outputs the sum or average value of six line image intensity distributions whose maximum values are aligned, in other words, whose phases are aligned. Therefore, the influence of line image fluctuation is removed, and an accurate line image intensity distribution due only to the tested lens can be obtained. Using this, the computer 7 performs a Fourier transform calculation to improve accuracy. High M
It becomes possible to measure TF.
第１図はＭＴＦ測定機の基本構成の１例を示す説明図、
第２図はそのテストチャートの１例を示す正面図、第６
図はその結像面のＣＣＤアレイの配置を示す正面図、第
４図は本発明のＭＴＦ測定方法における線像データ処理
回路のブロック図、第５図は」二記処理回路による線像
データの平均化のステップを示す説明図である。
２・・・スリット（線状パターン）
２′・・・線像 ６・・・テストチャート４
・・・被検レンズFIG. 1 is an explanatory diagram showing an example of the basic configuration of an MTF measuring device,
Figure 2 is a front view showing an example of the test chart, and Figure 6 is a front view showing an example of the test chart.
The figure is a front view showing the arrangement of the CCD array on the imaging plane, FIG. 4 is a block diagram of the line image data processing circuit in the MTF measurement method of the present invention, and FIG. FIG. 3 is an explanatory diagram showing an averaging step. 2...Slit (linear pattern) 2'...Line image 6...Test chart 4
...Lens to be tested
Claims (1)
せて得られた線像の強度分布を、ノイズ除去のため複数
回読取って平均化し、その強度分布をフーリエ変換して
上記被検レンズのＭＴＦを求めるレンズのＭＴ’Ｆ測定
方法において、上記の複数回読取られた線像の各回の強
度分布の最大値の位置が一致する如く強度分布の位相を
揃えて各部の強度を平均化することを特徴とするＭＴＦ
測定方法。The intensity distribution of the line image obtained by imaging the linear pattern on the test chart with the test lens is read multiple times and averaged to remove noise, and the intensity distribution is Fourier transformed to obtain the image of the test lens. In the method of measuring MT'F of a lens to obtain MTF, the intensity of each part is averaged by aligning the phase of the intensity distribution so that the position of the maximum value of the intensity distribution of each time of the line image read multiple times matches. MTF characterized by
Measuring method.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11688582A JPS599537A (en) | 1982-07-07 | 1982-07-07 | Method for measuring mtf |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11688582A JPS599537A (en) | 1982-07-07 | 1982-07-07 | Method for measuring mtf |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS599537A true JPS599537A (en) | 1984-01-18 |
Family
ID=14698046
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP11688582A Pending JPS599537A (en) | 1982-07-07 | 1982-07-07 | Method for measuring mtf |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS599537A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112985781A (en) * | 2021-04-27 | 2021-06-18 | 立臻科技(昆山)有限公司 | Lens test data processing method, device, equipment and storage medium |
-
1982
- 1982-07-07 JP JP11688582A patent/JPS599537A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112985781A (en) * | 2021-04-27 | 2021-06-18 | 立臻科技(昆山)有限公司 | Lens test data processing method, device, equipment and storage medium |
| CN112985781B (en) * | 2021-04-27 | 2021-08-10 | 立臻科技(昆山)有限公司 | Lens test data processing method, device, equipment and storage medium |
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