We demonstrate a method to fabricate varied-line-spacing grating by employing elastic medium with variable vertical section. The advantages of this technique include continuous diversity of variation of line-space, high fabrication efficiency and low cost, etc. It is very difficult or unrealizable to produce this variation of line-space by traditional interference lithography. This kind of grating can be used in the optical position sensor and it can improve the precision of the sensor.
In the analysis of line profile in single point Laser Direct Writing process, the line profile errors will increase if we replace the exposure dose distribution by the intensity distribution of focus plane because there are differences between them. The exposure dose distribution in the photoresist is analyzed as well as the line profile after developed. The experimental results agree well with the theoretical forecast.
As the micro-display applied to head-mounted display, the optical system not only suits for the small size of the micro-display, but also provides sufficient eye relief and exit pupil, and it becomes perplex. For settling this problem, a head-mounted display, which combines a hybrid diffractive-refractive eyepiece with a reflective relay system using a liquid crystal on silicon (LCOS) with the diagonal size 18mm, was designed. Basing on a Zeiss (60°) eyepiece, and replacing the doublet of it of a diffractive-refractive doublet, a hybrid eyepiece with 20mm eye relief and 10mm exit pupil was designed. The weight greatly reduced and the optical performance improved of the eyepiece compared with the Zeiss one. Considering the space for illuminating source of LCOS, a reflective relay system was used, which includes a flat half mirror and a concave mirror. The magnifying power of the relay system also makes the optical system suitable for the small size of LCOS. The system is with high performance, sufficient exit pupil and eye relief, and reasonable size and weight in the specific application of head-mounted display.
In the single point laser direct writing (LDW) process, there are differences between the exposure dose distribution and the light intensity distribution, and the differences will bring the line profile errors. In this paper, the equations to calculate the exposure dose distribution for the polar coordinate laser direct writing system are presented. The differences between the exposure dose distribution and the light intensity distribution are discussed. The line profile in the photoresist after development is predicted. The experimental results agree well with the theoretical forecast.
Harmonic diffractive surface element is successfully introduced to the system of infrared dual band in this paper. It has been simultaneously accomplished that the rectification of the Transverse ray, Lateral color and Longitudinal aberration in both band, wave front aberration less ¼ wave length and Modulation Transfer Function of dual band approaching or attaining the diffraction limit. The properties of action spectrum of harmonic diffractive are between refractive element and diffractive, which debased the demand for technical level. The practical design not only shows that the system is compact, few elements and high rates of transmission but also has better weaken-ray aberrations character and 100% cool diaphragm efficiency. The harmonic diffractive element offers a new component for optics designs.
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