Abstract:
PROBLEM TO BE SOLVED: To provide a method for measurement of an object capable of removing noise signals keeping speedy measurement using spectral interference, and to provide an ophthalmic apparatus using the method. SOLUTION: A part of light with short coherent length is projected onto an object to make the reflection light the object light and part of light with short coherent light is made the reference light. The object light and the reference light are synthesized and interfered. The obtained interference light is spectralized into prescribed frequency components and photo-received as photo-reception light signals. Fourier or inverse Fourier transformation is performed on the photo-reception signals for tomographic imaging of a phase object or measurement of optical surface profile. Fourier or inverse Fourier transformation is performed on the information calculated by subtracting signal components of sums of respective autocorrelation signals of the object light and the reference light included in the photo-receiving signals to obtain image information on the object. COPYRIGHT: (C)2006,JPO&NCIPI
Abstract:
PROBLEM TO BE SOLVED: To eliminate the influence to an absorption spectrum even if interference waveform is distorted by the mixture of noise and the unstable factors of a light source and a detector. SOLUTION: Two measurement interference waveform data that are continuous in time are held in a memory onec (S12), the amount of noise and the degree of similarity are calculated from the data at an end section and at a center section, respectively (S14, S15), and an index value E for judging whether interference waves are conforming or not is obtained from them (S16). When the index value E is equal to or less than a threshold Et that is determined by measurement in advance, it is judged that the interference waves are appropriate and the waveform is integrated (S17, S18). In the case of the mixture of noise due to turbulence or the like, and the unstable state until a light source and a detector reach a stable state, the index value E increases, so that it is judged to be-nonconforming waveform and is excluded from integration, thus preventing the integral waveform from being distorted and increasing the accuracy also in absorption spectrum obtained from Fourier transform from it.
Abstract:
PURPOSE:To obtain a final result in a short time by employing discrete Fourier transform and performing integration at every plural spectral points every time data on one point in an interference pattern is obtained. CONSTITUTION:The interference pattern 15 measured by an interferometer 10 is inputted to an A/D converter 20 in time series to obtain a digital value 42, which is inputted to a digital multiplier 40. The value of specific wavelength lambda1 stored in a wavelength storage device 60, on the other hand, is stored in a memory 61 and inputted to a cosine function generator 30, which inputs a phase corresponding to the optical path difference (x) of the interference pattern f(x) and the cosine function value 43 of frequency in inverse proportion to the wavelength lambda1 to a multiplier 40. The multiplier 40 multiplies the digital value 42 and function value 43 to obtain the product 44. A memory 51, on the other hand, is stored with spectral intensity S(lambda1) corresponding to the wavelength lambda1 and this value and product 44 are added together and stored in the memory 51 again. Thus, real-time processing is performed to obtain the final result in a short time.
Abstract:
PURPOSE:To cut short-wavelength components and to execute a measurement by a high-sensitivity polarization and modulation system and an infrared photo- acoustic system by installing an optical filter made of a material which hardly transmits short-wavelength light of