Abstract: A distance measuring device based on laser interference reduces measurement errors caused by irregular air currents and the like on the measurement optical path, and realizes a high throughput and a high integration degree. The distance measuring device based on laser interference according to this invention includes a baffle structure member for causing a gas on the measurement optical path to flow as a laminar flow in a predetermined direction.

Abstract: Methods and apparatus are disclosed for microlithographically exposing a photosensitive substrate comprising single-exposure areas and multiple-exposure areas. After exposing the substrate, line widths in the single-exposure areas are substantially the same as line widths in the multiple-exposure areas. Also disclosed are masks comprising a first mask pattern used to expose the single-exposure areas once and a plurality of other mask patterns for exposing the multiple-exposure areas a predetermined number of times. Each of the other mask patterns allows a lower intensity of illumination light flux to be distributed to the multiple-exposure areas per exposure of the substrate than allowed by the first mask pattern. Consequently, the average intensity of illumination-light flux distributed to the single-exposure area after one exposure is substantially equal to the average intensity of illumination-light flux distributed to the multiple-exposure areas after a predetermined number of exposures of such areas.

Abstract: Projection exposure systems and methods are disclosed that achieve higher light intensities and reduce the time required for each exposure in multiple exposures of non-linear resists such as a two-photon-absorption resist. Using spatial redistribution of laser light, an illumination optical system forms an illumination region that illuminates only a portion of the pattern on a mask with spatially coherent light from a light source. The system forms the entire mask pattern on a substrate by repeating a non-linear exposure while moving the illumination region and the mask pattern relative to one another. To exploit temporal redistribution of laser light, an illumination optical system employs a pulsed-oscillation-type laser light source to form a mask pattern while varying the light intensity profile on a mask.

Abstract: An ultraviolet laser source which can stably emits ultraviolet light having a sufficient output and low coherence, as a light source for an exposure unit, for a long period of time, is compact, and allows easy maintenance. The laser source is constituted by 10.times.10 laser elements, i.e., a total of 100 laser elements. Each laser element includes a laser beam emitting section for emitting light having a long wavelength, i.e., visible or infrared light, and a wavelength converting section for converting the emitted laser beam into ultraviolet light. The laser beam emitting section includes a semiconductor laser, and a solid-state laser. The wavelength converting section contains a nonlinear crystal for converting the wavelength of incident light and outputting the resultant light.

Abstract: Laser light radiated from a laser device 12 enters a resonator 16, and an electric field applied to a BBO crystal 14 inside the resonator 16 modulates the resonance frequency of the resonator 16. The BBO crystal 14 has a modulation electrode 32 and a feedback electrode 34, and a photodetector 18 detects laser light modulated by the BBO crystal 14. A signal in proportion to an error in resonance frequency obtained from the photodetector 18 causes an electric field to be applied to the BBO crystal 14 via the electrode 32 to change the resonance length. Negative feedback control is thus provided to the resonance frequency of the resonator 16 which is determined by the electric field applied to the BBO crystal 14 to substantially eliminate error, thereby synchronizing the resonator 16.

Abstract: A multi-quantum well structure with a large second order optical nonlinearity and transparent at short wavelengths of up to 350 nm. is described. Alternating insulator and semiconductor layers are grown on a substrate to form a multi-quantum well structure, such that the potential function for electrons in the semiconductor layers is asymmetric in a direction normal to the substrate. Sub-bands of electrons in the conduction band lead to a large optical nonlinearity with efficient second harmonics generation, and is obtained by an appropriate selection of the width and shape of the well. The structure, preferably packaged on the same substrate of a laser diode, is used as an on-chip source of blue light.