Cold mirror

Abstract: An ultraviolet irradiation device of the optical path division type for treating a workpiece which is often subject to deformations and color changes due to heat, and in which the distribution of radiance is good and the average irradiance on the surface irradiated with light can be increased which can be achieved with light emitted from a rod-shaped lamp and reflected by a trough=shaped cold mirror being incident in cold mirrors which split the optical path. This light is thus divided into two parts and is incident in total reflection mirrors. On the other hand, the direct light emitted by the rod-shaped lamp is incident in second optical path splitting cold mirrors which divides this light and causes it to be incident in the total reflection mirrors. The light reflected by the total reflection mirrors is incident in heat reflection filters, and is transmitted by the heat reflection filters so as to be radiated onto a workpiece. On the workpiece the light divided into two parts is radiated such that the two beams of light come to lie partially superimposed one on top of the other. This improves the radiance distribution. Furthermore, light shielding components can also be used instead of the second optical path splitting mirrors.

Abstract: An all-polymeric cold mirror which reflects visible wavelengths while transmitting a substantial portion of infrared wavelengths is provided. The mirror includes a sufficient number of alternating layers of at least first and second diverse polymeric materials such that at least 50% of peak reflecting visible light of a wavelength of between about 380-680 nm incident on the mirror is reflected and at least 50% of infrared light between about 680-2000 nm is transmitted or absorbed. The mirror may be designed so that it either reflects or absorbs ultraviolet light.

Abstract: The eye-tracking system is based on the reflection of four light emitting diodes (LED)s at the cornea of user's eve. The LEDs emit infrared light at 900 nanometers and the virtual images formed behind the cornea as well as a near infrared image of the pupil are displayed on a charged couple device (CCD) sensor. The optical system used to display virtual environments is also used to conjugate the virtual images of the LEDs to the CCD sensor. This optimizes the integration of eyetracking system into the head mounted device (HMD). The four LEDs are laid out around the imaging (optical) system and their beam (rays) impinge directly on the eye by reflection on the hot mirror. Then the light reflected by the cornea is reflected again by the hot mirror, goes through the optical system and the cold mirror to be imaged on the sensor. The whole eye is illuminated by near infrared light and the contrast between the dark pupil and the bright iris on the CCD sensor allows knowledge of the location of the center of the entrance pupil. The processing of the location of the cornea images and the center of the entrance pupil leads to determine the sight direction.

Abstract: A projector system includes a light pipe integrator (LPI) between its lamp and its projection lens system. The LPI is hollow, formed from sheet metal, and has an internal cold mirror coating which reflects visible light and passes infra-red radiation. The reflector is a compound reflector having profiles of two ellipses with different eccentricities.