Grating Optical Low-Pass Filter

Fujisawa, Katsuya; Nishida, Masao Uetsuki

doi:10.1143/jjap.35.1768

Cited by 11 publications

(5 citation statements)

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“…We have also fabricated the optical spatial filter on the basis photolithography and reactive ion etching, 6) instead of using a photoreactive polymer 7) or transparency sheets. 8) The etched depth d was determined in order to realize the binary phase of π according to…”

Section: Resultsmentioning

confidence: 99%

Phase-Modulation Optical Spatial Filters Applicable to Inspection Systems for Patterned Silicon Wafers

Yamamoto¹,

Iwata²,

Minakata³

2000

Jpn. J. Appl. Phys.

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We have studied a method to realize an optical spatial filter applicable to inspection systems for patterned silicon wafers by means of a phase-modulation filter. A simulated-annealing method can be used to design a one-dimensional binary phase spatial filter which effectively levels a periodic pattern corresponding to memory cells and so on. The optimum cost function is the maximum optical amplitude on the observation plane of the inspection system. The suitable binary phase ranges from 0.7π to 1.3π . Furthermore, leveling of a nonperiodic pattern corresponding to particles or defects can be avoided when the cells of the spatial filter which make no contribution to the leveling of the periodic pattern are set to have the same phase as that of the cell at the lowest spatial frequency. As a result, the nonperiodic patterns can be emphasized more than periodic patterns. To verify the applicability of the simulation, we fabricated the designed optical spatial filter on a quartz substrate by photolithography and reactive ion etching, and measured its characteristics. As a result, we have confirmed that the fabricated optical spatial filter has the same effect as that of the designed one.

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Section: Resultsmentioning

confidence: 99%

Phase-Modulation Optical Spatial Filters Applicable to Inspection Systems for Patterned Silicon Wafers

Yamamoto¹,

Iwata²,

Minakata³

2000

Jpn. J. Appl. Phys.

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“…This stack of a few birefringent crystals of the BOLPF occupies a lot of space, which is an impediment for minimization of the imaging device. An alternative to the bulky BOLPF is the thin phase diffraction grating optical low-pass filter (OLPF) or (GOLPF) in-troduced in [2]. Unlike the BOLPF, in which distance from the image sensor has little effect on performance, the GOLPF has a strong dependence on the distance between the filter and sensor, the wavelength of the incident light, and the intensity distribution in the diffracted beams [3].…”

Section: Introductionmentioning

confidence: 99%

Adjustable active optical low-pass filter

Kreymerman

2012

Appl. Opt.

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This paper presents an active optical low-pass filter (AOLPF) capable of changing the resolution of an imaging system on demand in order to remove aliasing noise from a sampling image. This is advantageous over conventional optical low-pass filters, which are fixed image-blurring optical components that are built into the imaging system, in order to remove aliasing in the image. Furthermore, conventional filters smear images regardless of the presence or lack of high spatial frequency, which can exceed the Nyquist limit of the sensor. On the contrary, the proposed AOLPF can dynamically adjust the modulation transfer function of an imaging system to eliminate aliasing artifacts. In addition, this filter can be turned off in the absence of high spatial frequency to maximize resolution and prevent unnecessary blurring of the sampling image.

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“…iaturization of the a module into the easing the number o reduce thickness ave been reported xample, a grating ported in [2][3] [4] , which is thinner OLPFs.…”

Section: Introductionmentioning

confidence: 99%

Ultra-small imaging system for cell phone camera using birefringent lenses

Zhang

Ueda

2011

2011 IEEE SENSORS Proceedings

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In this research, an ultra-small ima birefringent lenses was presented. This syste the next generation mobile phone camera wit of smaller pixel size. The system thickne approximately 1.7mm (from the first lens' fr image sensor) by employing one aspheric lens lens made of birefringent uniaxial crystal, wh optical low pass filters (OLPFs). In conve however, the OLPFs are stacked up and ass with optical lenses, which makes it difficult thickness. Quantitative and visual results of or ordinary ray separation on the image plane d the birefringent lenses system is able to cut of frequencies than the Nyquist frequency of image sensor.I.

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Grating Optical Low-Pass Filter

Cited by 11 publications

References 0 publications

Phase-Modulation Optical Spatial Filters Applicable to Inspection Systems for Patterned Silicon Wafers

Phase-Modulation Optical Spatial Filters Applicable to Inspection Systems for Patterned Silicon Wafers

Adjustable active optical low-pass filter

Ultra-small imaging system for cell phone camera using birefringent lenses

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