Hamamatsu-photonics K.k.

Hamamatsu Photonics Kabushiki Kaisha

Yuji Kobayashi

Tsutomu Hara

Haruyoshi Toyoda

Naohisa Mukohzaka

Narihiro Yoshida

Takashi Inoue

Naoya Matsumoto

Norihiro Fukuchi

Terushige Hori

Tamiki Takemori

Yoshiharu Ooi

Tamiki Tekemori

In an apparatus for modulating light, a spatial light modulator includes a plurality of pixels and configured to modulate input light in response to a drive voltage for each of the pixels. An input value setting unit is configured to set an input value for the each of pixels. The input value is a digital value, an entire gray level of the digital value is 'N', and 'N' is a natural number. A converting unit is configured to convert the input value to a control value. A control value is a digital value, an entire gray level of the control value is &#x201c;M&#x201d;, and &#x201c;M&#x201d; is a natural number greater than &#x201c;N&#x201d;. A driving unit is configured to convert the control value to a voltage value and drive the each of the pixels in response to the drive voltage corresponding to the voltage value.

Apparatus having spatial light modulator and converting unit converting input value to control value to control spatial light modulator

In an apparatus for modulating light, an spatial light modulator includes a plurality of pixels and configured to modulate input light in response to a drive voltage for each of the pixels. An input value setting unit is configured to set an input value for the each of pixels. The input value is a digital value, an entire gray level of the digital value is 'N', and 'N' is a natural number. A converting unit is configured to convert the input value to a control value. A control value is a digital value, an entire gray level of the control value is &#x201c;M&#x201d;, and &#x201c;M&#x201d; is a natural number greater than &#x201c;N&#x201d;. A driving unit is configured to convert the control value to a voltage value and drive the each of the pixels in response to the drive voltage corresponding to the voltage value.

A phase-modulating apparatus includes a spatial light modulator, an input value setting unit, a plurality of sets of reference data, a converting unit, and a driving unit. The input value setting unit sets an input value for each pixel. Each set of reference data corresponds to at least one pixel. The converting unit converts an input value inputted for each pixel to a control value by referencing the corresponding set of reference data. The driving unit converts the control value to a voltage value. The driving unit drives each pixel with a drive voltage corresponding to the voltage value. Each set of reference data correlates a plurality of first values from which input values are taken, and a plurality of second values from which control values are taken to ensure that the relationship between the plurality of first values and phase modulation amounts attained by the corresponding at least one pixel is a prescribed linear relationship.

Phase-modulating apparatus

In a spatial light modulator of the present invention, a photoconductive layer formed of photoconductive material receives write light having a spatial distribution in its intensity and changes resistivity of the photoconductive material dependently on the spatial distribution in the intensity of the received write light. A liquid crystal layer formed of liquid crystal molecules of nematic phase receives read light and presents birefringence with respect to the received read light. An electric voltage is applied through the photoconductive layer and the liquid crystal layer to thereby produce an electric field in the liquid crystal layer. The photoconductive layer changes the electric field produced in the liquid crystal layer in accordance with the resistivity of the photoconductive material so as to electrically control the birefringence of the liquid crystal molecules. The liquid crystal layer modulates the received read light in accordance with the birefringence which is electrically controlled in accordance with the spatial distribution in the intensity of the write light received by the photoconductive layer.

Phase-only optically-addressed type spatial light modulator

In an individual identification apparatus, a hologram 11 recorded on a card is irradiated with laser light to read out a fingerprint image of a specific person. A finger of an arbitrary person to be identified with the specific person is irradiated with laser light to obtain a fingerprint image. Thus obtained fingerprint images are jointly written in a first SLM. Then, the joint image is read out and Fourier transformed to obtain a Joint Fourier Transform image, which is then written in a second SLM. The Joint Fourier Transform image is then read out and Fourier transformed to obtain a pair of output correlation peaks. A photodetector detects the intensity of the output correlation peaks and outputs a signal indicative of the intensity. A threshold processor compares the value of the signal with a predetermined threshold value to positively or negatively identify the arbitrary person with the specific person.

Apparatus for identifying an individual based on a fingerprint image

In an optical detector, a light source irradiates coherent light onto an objective. A Fourier transform lens receives the light diffracted and scattered at the objective and Fourier transforms the light to generate a Fourier image, the Fourier image having a high intensity spectral component corresponding to the periodic pattern on the objective and a low intensity spectral component corresponding to the abnormal portion. In an optically-addressed spatial light modulator, each of the optically-addressing part and the light modulating part receives the Fourier image at the corresponding portions. A threshold driving controller controls the spatial light modulator in its threshold operation so as to change a state in the light modulating part at a region where the high intensity spectral component of the Fourier image is incident while preventing the state from being changed in the light modulating part at a region where the low intensity spectral component of the Fourier image is incident, the changed state in the light modulating part modulating the high intensity spectral component of the Fourier image incident in the light modulating part. Thus, the modulated high intensity spectral component is separated from the unmodulated low intensity spectral component.

Optical detector employing an optically-addressed spatial light modulator

A spatial Fourier transforming apparatus jointly Fourier transforms a plurality of input images to obtain a Joint Fourier transform image of the plurality of input images. The apparatus comprises: input means for inputting a plurality of input images; a mask member having a plurality of aperture edges for defining a plurality of apertures each for transmitting a part of a corresponding one of the plurality of input images, the plurality of aperture edges having low correlation; and Fourier transforming means for jointly Fourier transforming the parts of the plurality of input images having passed through the plurality of apertures and for obtaining a Joint Fourier Transform image of the plurality of input images.

Apparatus for performing a joint fourier tranform utilizing apertures of

An optical displacement measuring apparatus of the present invention optically measures a displacement amount of an object. The apparatus includes: image forming means for forming an image indicative of the displacement amount of the object achieved between first and second timings; first modulating means for modulating coherent light in accordance with the image; first Fourier transform means for subjecting the coherent light modulated by said first modulating means to Fourier transformation to thereby form a first Fourier image; second modulating means for modulating coherent light in accordance with the first Fourier image; second Fourier transform means for subjecting the coherent light modulated by said second modulating means to Fourier transformation to thereby form a second Fourier image; detecting means for detecting peak position of the second Fourier image indicative of the displacement amount of the object between the first and second timings; and time interval adjusting means for adjusting a time interval defined between the first and second timings.

Optical displacement measuring apparatus utilizing Fourier transform

An input incoherent optical image to be supplied to a microchannel spatial light modulator (MSLM) is produced by a CRT in accordance with an input electric signal provided from a computer. An output coherent optical image is read-out by launching a laser beam into an electro-optic material incorporated in the MSLM which stores the input image as a refractive index distribution.

Spatial light modulating device with CRT input image

A spatial light modulator includes an electro-optic crystal plate and a mesh electrode for capturing secondary electrons emitted from the crystal plate. Primary electrons carrying an image corresponding to an input optical image are incident on the front surface of the crystal plate to write a charge pattern thereon. In a writing operation, a dc voltage and a ramp voltage is applied to the mesh electrode and the back surface of the crystal plate, respectively. The dc voltage and a variation range of the ramp voltage are shifted to obtain a desired input/output characteristic of the device. Alternatively, a decreasing rate of the ramp voltage is changed to obtain a desired characteristic.

Spatial light modulation device capable of arbitrarily selecting an

An object is typically illuminated by laser light, and reflected light carrying a speckle pattern is amplified by an image intensifier. First and second speckle patterns representing the object before and after its deformation, respectively are written by double writing into a ferroelectric liquid crystal spatial light modulator (FLC-SLM). The double-written image is read out from the FLC-SLM, and converted by a Fourier transform optical system into an output optical image, i.e., Young's fringe. The output optical image is detected by a photoelectric converter, and analyzed by an image processing device to determine a deformation of the object.

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Hamamatsu, Japan

Yuji Kobayashi