公开(公告)号：JPH07167712A

公开(公告)日：1995-07-04

申请号：JP20102594

申请日：1994-08-25

Applicant: ADVANTEST CORP

Inventor： ARAKAWA NORIO ,  YAMAGUCHI TAKAHIRO ,  WATANABE SHINICHI ,  NIKI NAOHARU

IPC: G01J3/28 ,  G01J3/45 ,  G01R23/16

Abstract: PURPOSE:To prevent a resolution at the side of a longer wavelength from being lowered even when a display is made by areas of wavelengths, by providing a setting means for setting an area of a required measuring wavelength by a lower limit wavelength and an upper limit wavelength, etc. CONSTITUTION:A setting means 21 sets an area of a required measuring wavelength in a prescribed wavelength area by a lower limit wavelength and an upper limit wavelength. A wavelength/frequency converting means 17A converts the lower and upper limit wavelengths to corresponding frequencies. A deciding means 17B decides whether or not a prescribed switching frequency is present in the set wavelength area. A plurality of data are taken while a multiplication of a multiplication converter circuit 15 is changed, and synthesized to display a spectrum of an approximately equal wavelength resolution. In other words, a signal from the same to-be-measured object is measured for a plurality of the number of times while the multiplication is changed, and the data are taken into a buffer memory 16 at every measuring time. A fast Fourier transformation circuit 18 transforms the data taken in the memory 16 at high velocity. The data written in a main memory 19 and synthesized, so that one display data are obtained.

公开(公告)号：JPH0585851B2

公开(公告)日：1993-12-09

申请号：JP14582786

申请日：1986-06-20

Applicant: ADVANTEST CORP

Inventor： ARAKAWA NORIO ,  YAMAGUCHI TAKAHIRO ,  NIKI NAOHARU ,  WATANABE SHINICHI

IPC: G01J9/02

公开(公告)号：JPS6345514A

公开(公告)日：1988-02-26

申请号：JP19008586

申请日：1986-08-13

Applicant: ADVANTEST CORP

Inventor： ARAKAWA NORIO ,  YAMAGUCHI TAKAHIRO ,  NIKI NAOHARU ,  WATANABE SHINICHI

IPC: G01J3/02 ,  G01J3/457

Abstract: PURPOSE:To improve the resolution of a spectrum analyzer by finding a partial sum by multiplying part of a power spectrum by the 2nd window function. CONSTITUTION:A signal in some as data which is AD-converted by an AD converter 7 and inputted to a buffer memory 16 is read out by a microcomputer 17 and then multiplied by a hanning window by the 1st window function multiplying means 17A. Further, analytic data converted into the power spectrum is supplied to an extracting means 17C and part of the spectrum is multiplied by the 2nd window function to extract plural power spectrum groups while the 2nd window function is shifted in position successively from the spectrum; and the sum of the extracted power spectrum groups is calculated by an adding means 17D to calculate the partial product. This partial product is an interpolating value which interpolates respective frequency analytic components of the power spectrum, thereby improving the resolution.

公开(公告)号：JPS633230A

公开(公告)日：1988-01-08

申请号：JP14667086

申请日：1986-06-23

Applicant: ADVANTEST CORP

Inventor： YAMAGUCHI TAKAHIRO ,  ENOMOTO KOJI ,  ARAKAWA NORIO ,  WATANABE SHINICHI ,  NIKI NAOHARU

IPC: G01J3/45

Abstract: PURPOSE:To perform correct Fourier transform processing by performing squaring arithmetic and adding arithmetic and finding a maximum value. CONSTITUTION:Interference light from an optical interferometer 21 is converted by a photodetector 15 into an electric signal, which is converted by an AD converter 24 into a digital signal. This is increased in magnification by a magnification varying circuit 25 and fetched in a buffer memory 33. At this time, a real and an imaginary part which are the outputs of switches 31 and 32 of the circuit 25 are squared by squaring devices 41 and 42. Their squared values are added together by an adder 43, and the maximum value of the addition result is detected by a maximum detector 44. Data at the point of time when the maximum value is obtained is regarded as a reference point of time and data required for the Fourier transform processing is fetched out of the memory 33 and processed by fast Fourier transformation. Thus, the result of the correct fast Fourier transformation which is maximum at the center point of time at any time and has a nearly symmetrical waveform is obtained.

公开(公告)号：JP2509154B2

公开(公告)日：1996-06-19

申请号：JP20102594

申请日：1994-08-25

Applicant: ADVANTEST CORP

Inventor： ARAKAWA NORIO ,  YAMAGUCHI TAKAHIRO ,  WATANABE SHINICHI ,  NIKI NAOHARU

IPC: G01J3/28 ,  G01J3/45 ,  G01R23/16

公开(公告)号：JPS62180228A

公开(公告)日：1987-08-07

申请号：JP2465986

申请日：1986-02-05

Applicant: ADVANTEST CORP

Inventor： ARAKAWA NORIO ,  YAMAGUCHI TAKAHIRO ,  WATANABE SHINICHI ,  NIKI NAOHARU

IPC: G01J3/02 ,  G01J3/28 ,  G01J3/45 ,  G01R23/16

Abstract: PURPOSE:To display a spectrum with resolution at almost equal intervals over the entire wavelength range by making the power of power converting circuit different and displaying the spectrum of nearly equal wavelength resolution. CONSTITUTION:A desired measurement range is set with a lower-limit wavelength and an upper-limit wavelength within a wavelength range prescribed by a setting means 21. Those lower-limit and upper-limit wavelengths are converted by a wavelength-frequency converting means 17A to corresponding frequencies. Then, a deciding means 17B decides whether or not a prescribed switching frequency is present in the set range. When the frequency is present, a band calculating means 17C calculates the 1st band width between the frequency corresponding to the short-wavelength side lower-limit wavelength and the switching frequency and the 2nd band width between the switching frequency and the frequency corresponding to the longer-wavelength side upper-limit wavelength. A resolution correcting means 17D uses the 1st and the 2nd band widths to process respective thinning-out rates found on the short-wavelength and long-wavelength sides and data fetched at a center frequency by Fourier transform 18, and the data are displayed 9.

公开(公告)号：JPS631940A

公开(公告)日：1988-01-06

申请号：JP14582786

申请日：1986-06-20

Applicant: ADVANTEST CORP

Inventor： ARAKAWA NORIO ,  YAMAGUCHI TAKAHIRO ,  NIKI NAOHARU ,  WATANABE SHINICHI

IPC: G01J9/02

Abstract: PURPOSE:To measure the coherence length of a wave to be measured, by a method wherein the timewise or spatial interference fringe resulting from the interference of the wave to be measured is converted to an electric signal, and the square value of AD conversion output and the square value of the Hilbert transform value of the AD conversion output are added while the added value is extracted. CONSTITUTION:The wave to be measured from a light source 11 is inputted to an interferometer 21 and the obtained timewise interference fringe is inputted to a light detector 16 to be converted to an electric signal. This electric signal is supplied to an AD converter 22 and the digital signal converted is directly taken in a buffer memory 25 corresponding to the setting of switches 23, 24 or taken in a memory 25 through a magnification altering means 26. The digital signal value of the interference fringe taken in the memory 25 is inputted to an operation part 27. The operation part 27 operates the square of the inputted digital signal and the square of the Hilbert transform value of the digital signal and both square values operated are added and the added value is further evoluted. Accurate envelope can be detected on the basis of the extraction value obtained and an accurate coherence length can be measured.

公开(公告)号：JPS631939A

公开(公告)日：1988-01-06

申请号：JP14582886

申请日：1986-06-20

Applicant: ADVANTEST CORP

Inventor： YAMAGUCHI TAKAHIRO ,  ARAKAWA NORIO ,  NIKI NAOHARU ,  WATANABE SHINICHI

IPC: G11B7/12 ,  G01J9/00 ,  G01J9/02 ,  H03D1/00

Abstract: PURPOSE:To process the envelope of the original signal of an input signal in a real time, by respectively mixing the frequencies of first and second carrier wave signals in orthogonal relation and the frequency of an input digital signal and adding the square values of respective difference frequency components and further extracting the square root of the added value. CONSTITUTION:The light from a light source 11 is incident to an interferometer 21 and interference light is converted to an electric signal by a light detector 16. This electric signal is inputted to a magnification altering means 23 through an AD converter 22. A digital signal is applied to frequency mixing means 24, 25 to be respectively multiplied by first and second carrier waves. The second carrier wave has the same frequency as the first carrier wave and holds orthogonal relation different by 90 deg. in a phase with respect to the first carrier wave. The difference frequency components in the frequency mixing result obtained from the means 24, 25 are respectively supplied to LPFs 26, 27 and the outputs thereof are taken out at the cycle corresponding to set magnification by switches 30a, 30b. These outputs are squared by square means 28, 29 and the squared values are added by an adding means 31. The added value is subjected to evolution operation by an extraction means 32 and accurate envelope can be detected on the basis of the extraction result.