Disclosed is a random light collector device including a reflecting cavity configured to enclose a random light source that randomly transmits photons. The reflecting cavity has an inner wall adapted to reflect at least a portion of the photons to an output port and guiding means for directing the photons to a photodetector. The guiding means is a hollow tube having an inner wall adapted to reflect the photons, wherein a first end of the hollow tube is connected to or positioned adjacent to the output port of the reflecting cavity and wherein the photodetector is provided within the hollow tube or at a second end such that a sensitive area of the photodetector covers the cross-section of the second end.

An optical device includes: a light source part configured to project illumination light toward a sensing region; a photodetector configured to receive reflected light of the illumination light reflected on the sensing region; and a condenser mirror. The condenser mirror has a through hole through which the illumination light from the light source part passes and an optical axis of the light source part and an optical axis of the condenser mirror are aligned with each other. A reflection surface of the condenser mirror has a shape obtained by cutting out a columnar body extending in a projection direction of the illumination light, with a spheroid whose rotation axis is a major axis. The photodetector is disposed in a direction toward a first focal position of the condenser mirror. The sensing region is set in a direction toward a second focal position of the condenser mirror.

Methods and apparatuses for aligning and diagnosing the laser beam traversing an optical train in a highly space-efficient, lower cost and/or retrofit-friendly manner are disclosed. The optical components of the optical train are mounted such that one or more optical components can direct their exit laser beam to partially or wholly scan across one or more downstream sensors. Correlation data between physical disposition of optical components and the points of impact data and/or beam quality data are employed to, among others, align and/or diagnose the laser beam and/or localize failure sites and/or optimize maintenance schedule.

System, including methods and apparatus, for optical detection. The system may comprise a light source to generate a beam of light, an optical element, and a detector. The optical element may include a light guide having a shaft and a tip, with the tip forming a beveled end of the light guide. The optical element may extend into the beam, such that the tip and at least a portion of the shaft are located inside the beam, and a window of the optical element is located outside the beam. Light of the beam incident on the tip may be transmitted longitudinally through the light guide and out the window, while light of the beam incident on the shaft may be transmitted transversely through the shaft and remains in the beam downstream. The detector may be configured to detect light received from the window.

Disclosed is a random light collector device including a reflecting cavity configured to enclose a random light source that randomly transmits photons. The reflecting cavity has an inner wall adapted to reflect at least a portion of the photons to an output port and guiding means for directing the photons to a photodetector. The guiding means is a hollow tube having an inner wall adapted to reflect the photons, wherein a first end of the hollow tube is connected to or positioned adjacent to the output port of the reflecting cavity and wherein the photodetector is provided within the hollow tube or at a second end such that a sensitive area of the photodetector covers the cross-section of the second end.