Abstract: A LED illuminating device includes an illuminating unit and a shell having a top side and chamber. The illuminating unit includes a PCB supported by the shell and one or more LED modules electrically and spacedly mounted on the PCB disposed in the chamber. Each of the LED modules includes a red LED, a blue LED and a green LED which are symmetrically arranged in a triangular manner side by side. The shell is filled with transparent or translucence epoxy resin to cover the PCB, the root portions of electrical and power wires, which are electrically connected with the LEDs, and the chamber to seal the illuminating unit in the shell to form an integral body, wherein the wires are extended out from two ends of the top side of the LED illuminating device to the another neighboring LED illuminating device.

Abstract: The disclosure is directed to precise measurement of out-of-plane birefringence properties of samples of transparent optical material. Two angled-apart light beams are passed through a selected location of a sample optical element. One of the beams is incident to the sample surface. The characteristics of the beams are detected after passing through the sample, and the information detected is processed to determine the out-of-plane birefringence.

Abstract: Provided are methods for determining the birefringence level of optical material such as polymeric film. In one embodiment, the method uses a setup of optical components that has known system reference angle. The sample may be a stretched polymeric film that has a fast axis angle that has a predetermined orientation in the sample. The system is operated to align the direction of the fast axis of the sample with the reference angle of the system and to measure the birefringence level at a location of the sample. As one aspect of the invention, embodiments and methods are described for accurately determining birefringence levels across a very wide range and up to tens of thousands of nanometers.

Abstract: Purging of a light beam path in an effective manner that minimizes the affect of the purging requirement on system throughput. In one embodiment, the invention is incorporated into a birefringence measurement system that has several components for directing light through a sample optical element and thereafter detecting and analyzing the light. The segment of the beam path through the sample is isolated to reduce the volume that requires continual purging.

Abstract: A system and method for precisely measuring low-level linear and circular birefringence properties (retardance and direction) of optical materials (26). The system incorporates a photoelastic modulator (24) for modulating polarized light that is then directed through a sample (26). The beam (“Bi”) propagating from the sample is separated into two parts, with one part (“B1”) having a polarization direction different than the polarization direction of the other beam part (“B2”). These separate beam parts are then processed as distinct channels. Detection mechanisms (32, 50) associated with each channel detect the time varying light intensity corresponding to each of the two parts of the beam. This information is combined for calculating a precise measure of the linear and/or circular retardance induced by the sample, as well as the sample's fast axis orientation and direction of circular retardance.

Abstract: Provided are systems and methods for precisely measuring birefringence properties of optical elements, especially those elements that are used in deep ultraviolet (DUV) wavelengths. The system includes two photoelastic modulators (PEM) (126, 128) located on opposite sides of the sample (136). Each PEM is operable for modulating the polarity of a light beam that passes though the sample. The system also includes a polarizer (124) associated with one PEM, an analyzer (130) associated with the other PEM, and a detector (132) for measuring the intensity of the light after it passes through the PEMs, polarizer, and analyzer. Described are techniques for determining birefringence properties across a wide range. For example, a dual-wavelength source light embodiment is provided for measuring relatively high levels of birefringence.

Abstract: The disclosure is directed to precise measurement of out-of-plane birefringence properties of samples of transparent optical material. Two angled-apart light beams are passed through a selected location of a sample optical element. One of the beams is incident to the sample surface. The characteristics of the beams are detected after passing through the sample, and the information detected is processed to determine the out-of-plane birefringence.

Abstract: Provided are systems and methods using a Soleil-Babinet compensator (101) as a standard for calibrating birefringence measurement systems. Highly precise and repeatable calibration is accomplished by the method described here because, among other things, the inventive method accounts for variations of retardance across the surface of the Soleil-Babinet compensator (101). The calibration technique described here may be employed in birefringence measurement systems that have a variety of optical setups for measuring a range of retardation levels and at various frequencies of light sources.

Abstract: Purging of a light beam path in an effective manner that minimizes the affect of the purging requirement on system throughput. In one embodiment, the invention is incorporated into a birefringence measurement system that has several components for directing light through a sample optical element and thereafter detecting and analyzing the light. The segment of the beam path through the sample is isolated to reduce the volume that requires continual purging.

Abstract: Provided are systems and methods for precisely measuring birefringence properties of optical elements, especially those elements that are used in deep ultraviolet (DUV) wavelengths. The system includes two photoelastic modulators (PEM) (126, 128) located on opposite sides of the sample (136). Each PEM is operable for modulating the polarity of a light beam that passes though the sample. The system also includes a polarizer (124) associated with one PEM, an analyzer (130) associated with the other PEM, and a detector (132) for measuring the intensity of the light after it passes through the PEMs, polarizer, and analyzer. Described are techniques for determining birefringence properties across a wide range. For example, a dual-wavelength source light embodiment is provided for measuring relatively high levels of birefringence.

Abstract: A practical system and method for precisely measuring low-level birefringence properties (retardance and fast axis orientation) of optical materials (26). The system permits multiple measurements to be taken across the area of a sample to detect and graphically display (100) variations in the birefringence properties across the sample area. In a preferred embodiment, the system incorporates a photoelastic modulator (24) for modulating polarized light that is then directed through a sample (26). The beam (“Bi”) propagating from the sample is separated into two parts, with one part (“B1”) having a polarization direction different than the polarization direction of the other beam part (“B2”). These separate beam parts are then processed as distinct channels. Detection mechanisms (32, 50) associated with each channel detect the time varying light intensity corresponding to each of the two parts of the beam.

Abstract: A practical system and method for precisely measuring low-level birefringence properties (retardance and fast axis orientation) of optical materials (26). The system permits multiple measurements to be taken across the area of a sample to detect and graphically display (100) variations in the birefringence properties across the sample area. In a preferred embodiment, the system incorporates a photoelastic modulator (24) for modulating polarized light that is then directed through a sample (26). The beam (“Bi”) propagating from the sample is separated into two parts, with one part (“B1”) having a polarization direction different than the polarization direction of the other beam part (“B2”). These separate beam parts are then processed as distinct channels. Detection mechanisms (32, 50) associated with each channel detect the time varying light intensity corresponding to each of the two parts of the beam.

Abstract: A practical system and method for precisely measuring low-level birefrigence properties (retardance and fast axis orientation) of optical materials (26). The system permits multiple measurements to be taken across the area of a sample to detect and graphically display (100) variations in the birefrigence properties across the sample area. In a preferred embodiment, the system incorporates a photoelastic modulator (24) for modulating polarized light that is then directed through a sample (26). The beam (“Bi”) propagating from the sample is separated into two parts, with one part (“B1”) having a polarization direction different than the polarization direction of the other beam part (“B2”). These separate beam parts are then processed as distinct channels. Detection mechanisms (32, 50) associated with each channel detect the time varying light intensity corresponding to each of the two parts of the beam.

Abstract: A dynamic self calibration process periodically calibrates a system for precisely measuring low-level birefringence properties (retardance and fast axis orientation) of optical materials. Variations in birefringence measurements can be caused by, for example, changes in the environmental conditions ( e.g., ambient pressure or temperature) under which birefringence properties of a sample are measured. In one implementation, the dynamic self calibration process repeatedly calibrates the system at different selected frequencies to compensate for different selected baseline variations.