Diffraction grating

About: Diffraction grating is a research topic. Over the lifetime, 24884 publications have been published within this topic receiving 372437 citations. The topic is also known as: grating.

Recording of a continuous tone focused image on a diffraction grating

Abstract: A RECORDING MEDIUM BLANK IS EMPLOYED COMPRISING A SUBSTRATE HAVING A DIFFRACTION GRATING, COMPOSED OF A PLURALITY OF SPACED LINE RIDGES, ON A SURFACE THEREOF, TOGETHER WITH A PHOTORESIST DISPOSED ON THIS SURFACE WHICH FILLS THE SPACES BETWEEN ADJACENT LINE RIDGES. THIS PROVIDES A SUBSTANTIALLY SMOOTH EXTERIOR SURFACE OF THE PHOTORESIST WHICH IS SITUATED IN PROXIMITY WITH THE RESPECTIVE TOPS OF THE LINE RIDGES MAKING UP THE DIFFRACTION GRATING. BY EXPOSING SUCH A RECORDING BLANK TO A FOCUSED IMAGE OF ANY COMPLEX OBJECT AND THEN DEVELOPING THE PHOTORESIST, A DIFFRACTION GRATING WITH A MODULATED EFFICIENCY IS FORMED, CONSTITUTING A SYNTHETIC FOCUSED IMAGE HOLOGRAM; WHICH DISPLAYS THE ORIGINAL FOCUSED IMAGE WHEN PROPERLY VIEWED. A STAMPING MASTER, WHICH CAN BE PREPARED FROM THIS MODULATED GRATING RECORD, IS USEFUL IN EMBOSSING REPLICATIONS ON THERMOPLASTIC MATERIAL, SUCH AS VINYL FOR INSTANCE.

High-temperature multiparameter sensor based on sapphire fiber Bragg gratings.

Abstract: We present, for the first time to our knowledge, a dual strain/temperature sapphire fiber Bragg grating sensor. Temperature and strain coefficients of the grating are evaluated. By recording the blackbody radiation level above 650°C, wavelength shifts due to temperature can be decoupled from those due to strain.

Sampled grating, distributed feedback quantum cascade lasers with broad tunability and continuous operation at room temperature

Abstract: A dual-section, single-mode quantum cascade laser is demonstrated in continuous wave at room temperature with up to 114 nm (50 cm−1) of tuning near a wavelength of 4.8 μm. Power above 100 mW is demonstrated, with a mean side mode suppression ratio of 24 dB. By changing the grating period, 270 nm (120 cm−1) of gap-free electrical tuning for a single gain medium has been realized.

Corrugated-sidewall interband cascade lasers with single-mode midwave-infrared emission at room temperature

Abstract: We report interband cascade lasers operating in a single spectral mode (λ≈3.6 μm) at −5–30 °C. A corrugated pattern etched into both sidewalls of the 6- and 9-μm-wide ridges serves to suppress higher-order lateral modes by increasing their loss, and also provides a fourth-order distributed-feedback grating for longitudinal mode selection. Despite the grating’s weak coupling strength, the 9 μm ridge produced up to 12 mW per facet of single-mode cw output power at 25 °C, with a side-mode suppression ratio of >30 dB.

High aspect ratio gratings for X-ray phase contrast imaging

Abstract: Differential phase contrast X-ray imaging (DPCI) has gained a lot of interest in the past years. It is based on X-ray grating interferometry and the image quality is strongly dependant on the grating quality. Periodic line and space structures with periods in the micron range are required for the source and absorption grating. In case of energies > 30 keV their height should be larger than 100 μm resulting in aspect ratios of more than 100. Deep X-ray lithography and gold electroforming (LIGA technology) is used to fabricate these challenging structures. After resist, design and process optimization gratings with 2.4 μm period have been electroformed up to 120 μm, Visibilities of up to 70% for 29 keV and up to 20% for 52 keV have been achieved for monochromatic synchrotron light. Structures with larger periods could be manufactured up to 200 μm; further increase of the height and the gratings quality is possible yielding to high performance gratings also for high energies.