Biomedical subjects

Neimule Menke

Publications and source records attributed to Neimule Menke.

4 recordsLinked to original sources

PubMed2006

Optical image processing using the photoinduced anisotropy of pyrrylfulgide.

A synthesized photochromic compound-pyrrylfulgide--is prepared as a thin film doped in a polymethylmethacrylate (PMMA) matrix. Under irradiation by UV light, the film converts from the bleached state into a colored state that has a maximum absorption at 635 nm and is thermally stable at room temperature. When the colored state is irradiated by a linearly polarized 650 nm laser, the film returns to the bleached state; photoinduced anisotropy is produced during this process. Application of optical image processing methods using the photoinduced anisotropy of the pyrrylfulgide/PMMA film is described. Examples in non-Fourier optical image processing, such as contrast reversal and image subtraction and summation, as well as in Fourier optical image processing, such as low-pass filtering and edge enhancement, are presented.

Anisotropy↗

PubMed2005

Polarization holographic high-density optical data storage in bacteriorhodopsin film.

Optical films containing the genetic variant bacteriorhodopsin BR-D96N were experimentally studied in view of their properties as media for holographic storage. Different polarization recording schemes were tested and compared. The influence of the polarization states of the recording and readout waves on the retrieved diffractive image's intensity and its signal-to-noise ratio were analyzed. The experimental results showed that, compared with the other tested polarization relations during holographic recording, the discrimination between the polarization states of diffracted and scattered light is optimized with orthogonal circular polarization of the recording beams, and thus a high signal-to-noise ratio and a high diffraction efficiency are obtained. Using a He-Ne laser (633 nm, 3 mW) for recording and readout, a spatial light modulator as a data input element, and a 2D-CCD sensor for data capture in a Fourier transform holographic setup, a storage density of 2 x 10(8) bits/cm2 was obtained on a 60 x 42 microm2 area in the BR-D96N film. The readout of encoded binary data was possible with a zero-error rate at the tested storage density.

Journal Article↗

PubMed2005

Polarization multiplexed write-once-read-many optical data storage in bacteriorhodopsin films.

In polymeric films of bacteriorhodopsin (BR) a photoconversion product, which was named the F620 state, was observed on excitation of the film with 532 nm nanosecond laser pulses. This photoproduct shows a strong nonlinear absorption. Such BR films can be used for write-once-read-many (WORM) optical data storage. We demonstrate that a photoproduct similar or even identical to that obtained with nanosecond pulses is generated on excitation with 532 nm femtosecond pulses. This photoproduct also shows strong anisotropic absorption, which facilitates polarization storage of data. The product is thermally stable and is irretrievable to the initial B state either by photochemical reaction or through a thermal pathway. The experimental results indicate that the product is formed by a two-photon absorption process. Optical WORM storage is demonstrated by use of two polarization states, but more polarization states may be used. The combination of polarization data multiplexing and extremely short recording time in the femtosecond range enables very high data volumes to be stored within a very short time.

Journal Article↗

PubMed2003

[Holographic recording properties of BR-D96N film].

BR-D96N was a genetically mutated product of bacteriorhodopsin (BR) with obvious improved photochromic effect. Compared with the wild type BR, BR-D96N had a lifetime of M state prolonged to 5 min, showing obvious saturation absorption and lower light intensity in saturation absorption (0.4 mW/cm(2)). In case of holographic recording, dynamic grating was recorded in the BR-D96N film, its characteristic parameter was not light exposure energy but light intensity. The writing time of the holographic grating depended on the recording light intensity. The higher the recording light intensity, the faster the grating builds up. Under a weak reconstruction light, the recording light intensity resulting in maximal diffraction efficiency was consistent with the saturation absorption intensity. The reconstruction light could partly erase the grating. With lower intensity of reconstruction light, higher diffraction efficiency (1.8%) could be reached, but the diffraction intensity was not high. To get highest diffraction intensity, a properly high intensity of reconstruction light was needed (80 microW/cm(2)). The result of these experiments showed that holographic images could be recorded on the BR-D96N film.

Bacteriorhodopsins↗