Abstract: A device for optically evaluating test strips includes a housing carrying the measuring optics and a test strip holder insertable into and removable from the housing by sliding into and out of a receiving compartment of the housing, with the test strip holder containing all of the surfaces with which the significant portions of test strips come into contact, thereby permitting those surfaces to be easily cleaned upon removal of the test strip holder from the housing. The device also assures proper positioning of an easily inserted test strip, allows for heating of the test field to a fixed temperature, and allows for both empty and dark field calibration of the optical system.

Abstract: The invention concerns a differential-reflectance photometer for quantitatively evaluating test strips, especially for chemical analysis. The differential-reflectance photometer is characterized in that two optical channels are arranged in one housing in V-shaped fashion with each channel receiving an optical emitting and an optical receiving arrangement, that the channels enter a common space at the apex of the V, that a reference field associated with both emitting and receiving arrangement is provided on the bottom of the common space, that the emitting and receiving arrangements are connected to a common evaluation apparatus, and in that between the reference field and the emitting and receiving arrangements is a receiving slot, which intersects both channels, for receiving a test strip with two test fields each of which becomes associated with a respective one of the two channels.

Abstract: A method for using mass-produced light-emitting diodes of a predetermined luminance in instruments requiring a precise luminance value and a light-emitting diode arrangement for adapting such mass-produced light emitting diodes to such instruments. The above-noted method includes the steps of disposing an LED in a lengthwise adjustable manner within a sleeve, closing the sleeve with a light diffusing disc at an end thereof from which the light from the LED is intended to merge and displacing the LED within the sleeve in such a manner that a precisely defined luminance appears at the diffused disc. In accordance with a preferred embodiment of the apparatus, a tubular sleeve of an elastic plastic material is provided with mounting threads at one end thereof for mounting same within a cap with a light-diffusing disc located between the threaded end of the sleeve and the cap. Additionally, the sleeve is provided with longitudinally extending beads within which electrical connectors of the LED can be mounted.

Abstract: A light-emitting diode arrangement with a light-emitting diode that is light-transmissive in an axial direction of the type used in examining instruments for opthalmic optics. The light-emitting diode serves as a constant light source in conjunction with a diffusion disk, such as for fixation point stimuli, while the disk also serves as a stimulus that is lit by an additional, switchable light source, such as an incandescent lamp, whose light is transmitted through a light guide, such as an optical fiber, through the light-emitting diode to the disk. In a preferred embodiment, a color filter is arranged between the additional light source and the light-emitting diode and both the additional light source and light-emitting diode are axially displaceable relative to the diffusion disk so as to enable adjustment of their respective luminous densities.