JPS5992326A - Mtf measuring machine - Google Patents

Abstract

PURPOSE:To shorten the setting time of a lens by calculating the MTF of a lens to be measured and illuminance on an image-formation surface at a time from video signals from respective linear image sensors of an MTF measuring machine. CONSTITUTION:Light sources such as fluorescent lamps 11 and 12 light up a chart plate 14 having charts 13 (131-13m) consisting of slits and images of the charts 13 are formed on photodetection surfaces of linear image sensors 16 consisting of charge-coupled elements through the lens 15 to be measured. The charge-coupled elements 16 are so arranged that the direction of an array of numbers of photoelements phi1-N is perpendicular to the lengthwise direction of the images 13a of the slits 13, convert short-directional illuminance distributions of the slit images 13a into electric signals, and output a video signal in time series by self-scanning. This video signal is processed by Fourier transformation to calculate the MTF value of the measured lens 15 and illuminance on the image-formation surface.

Description

[Detailed Description of the Invention] (J branch) Honkomei+J: Concerning 71 MTF measuring instruments that measure the MTF of lenses.

ω Yume Technique D 1/'r - Lens MTF measurement and result (image surface illuminance 4
The measurement distance of 1i was carried out using separate measuring machines, and therefore the lenses σ) set iCl+, iCl+ and iCl+ were used.

(Tsuki Shiro'su) The present invention + J- A MT that eliminates the above drawbacks by simultaneously measuring the MTF and imaging surface illuminance of the lens.
The purpose is to provide an F measuring device.

C f1. D The present invention will be described below by way of examples with reference to the drawings.

FIG. 11(a) shows the optical system in Example 1C of the present invention 1-6 A light source consisting of two fluorescent lamps 11 and 12 illuminates a chart board 14 having charts 1 and 13 consisting of slits. However, the image of the chart 13 is focused by the lens 15 to be measured on the light receiving surface of a primary/primary image sensor 16 made of a hexagonal coupling element. The load-binding purple child 16 has a large number of photoelements φ~N
are arranged on a straight line and f&4 of slit 13
The longitudinal direction of the slit 13a is arranged so as to be opposite to the IU direction, and the irradiation distribution in the spore direction (width direction) of the slit 1 lea is controlled in time series by self-fixation using the electric signal.
As shown in the figure, the video signal is outputted as a video signal. This video signal is subjected to Fourier transform 8!.
be done. In general, the MTF III of a lens is σ) which varies depending on the image height position, radial direction, and tangential direction in addition to the lens performance.
A plurality of Surins 131 to 16m and charge coupled devices 161 to 16m are arranged in the carrier.

M of the wall frequency f (!'y+#i) of the Bolens to be measured
'rF11+MTF(f) is the following Fourier transform equation 11
By 1, cut A-sa' and K: pickpocket
11 Width correction ++i■□2'Kametake coupling element output (
1-φ~N)
As shown in Fig. 1(b), the output of -(change 1
-ru.

Since the peak value of the output of the charge coupled device 16 differs depending on the lens performance (MTF) K of the lens 15 to be measured, in order to measure the illuminance distribution of the lens 15, the output of the charge coupled device 16 is The liability of 1 (+'j must be equal to QIA-17.

This can be done by using an MTF measuring device to set the value of IU in the fI1 formula for each high-earning race.

FIG. 3 shows the construction of the circuit section in this embodiment. Each statue height i6. Two charge-coupled devices 161 to 16m are arranged for the radial power cycle and the tangential power cycle. One of the output signals of these charge-coupled devices 161 to 16m (F-) is selected by the multiplexer 17VC and converted into a signal Vcll by the analog/digital converter 18, and then sent to the random access memory (RAM). 19 VC is taken in.

σ) The signal taken into the RAM 19 is corrected in the arithmetic circuit 20 by the correction value from the time when the sensitivity of the photoelement of the charge-coupled device 16 and the dark current is not melted. (2) Not shown/Circuit 22
Using the data of sin and cos from
The output signals of f) and children 161 to 16m are then selected by the multiplexer 17 and similarly &,) processed IH
The MTF value and illuminance distribution for each city, radial direction, and radial direction were obtained for 1L4).

As described above, according to the present invention, the MTF and illuminance of the lateral leg lens are simultaneously measured from the video signal from the one-dimensional image sensor valley in the MTF fJIH constant.
The time required to set the lens to be measured can be shortened.

[Brief explanation of the drawing]

Figure 1 (al (b) is an example of the present invention) shows the optical system; Figure 2 (al) shows the waveform diagram showing the oblique diagram and its video signal; Figure 2 (b) shows the charge coupling Figure 6 is a block diagram showing the steps 15 of the above implementation sequence. 20... Adventure circuit.

Claims (1)

[Claims] A light source, a plurality of charts illuminated by the light source, a plurality of one-dimensional image sensors on which images of the charts are formed by a lens to be measured, and a video signal from each of the one-dimensional image sensors. Simultaneously calculate the MTF of the measuring lens and the resultant lens (111a).
MTF measurement tool.