Abstract: The invention relates to an infrared optical system which is capable of providing an effective focal length of about 240 mm, but fitting into a spherical package whose diameter is approximately 150 mm. To achieve such a degree of compactness, the invention employs an optical path including three reflections, which in combination define a question-mark-shaped optical path. Between the first and second reflections, the transmitted beam is passed through a focal plane and then is recollimated, and the collimated beam is then passed through the succeeding two reflections, after which it is directed telecentrically onto a detector. The invention further relates to a specific combination of lenses.

Abstract: The invention relates to an infrared optical system which is capable of providing an effective focal length of about 240 mm, but fitting into a spherical package whose diameter is approximately 150 mm. To achieve such a degree of compactness, the invention employs an optical path including three reflections, which in combination define a question-mark-shaped optical path. Between the first and second reflections, the transmitted beam is passed through a focal plane and then is recollimated, and the collimated beam is then passed through the succeeding two reflections, after which it is directed telecentrically onto a detector. The invention further relates to a specific combination of lenses.

Abstract: A device for use with infrared lenses to determine the optimum focal plane. The device comprises an infrared energy source, a collimating lens and an energy sensor to determine the energy level from the energy source to provide a normalizing signal. An infrared energy detector may be moved toward and away from the lens which is to be calibrated in order to test various planes within the depth of focus of the lens. A knife edge shutter is stepped across the path of energy at each of the positions to determine specific read outs of energy at each position of the knife edge shutter. The energy which passe the knife edge shutter is then delivered to a computer where the signal has been normalized by the sensor previously described. The computer reads out the signals corresponding to energy level at successive steps of the knife edge shutter. The computer is programmed to step the detector to successive positions and then the shutter to successive positions across the focal plane.

Abstract: A two-cycle engine in such as an outboard motor includes an engine shaft and a flywheel mounted on the shaft and having an inner cylindrical hub portion. A rubber-like magnet strip is adhesively attached about the hub portion with an outer protective shield adhesively bonded to the strip. The strip includes upper and lower magnetic areas which are oppositely and radially magnetized to establish an axially directed field adjacent the outer periphery of the strip. A triggering coil unit includes a C-shaped core with the poles of the core radially aligned with the upper and lower areas of the magnet strip such that the field passes therethrough. The strip is magnetized after assembly by an electromagnetic unit having a semi-circular core with a U-shape cross-section aligned with the strip.

Abstract: An outboard motor unit includes a shift lever pivotally mounted on a shaft to one side of powerhead with a central vertical neutral position and pivoted forwardly and rearwardly for forward and reverse drive. The unit includes an electric starter and a start pushbutton control mounted forwardly of the pivot shaft. The shift lever is formed with a forwardly projecting interlock plate having a central notch aligned with the button only in the neutral position. Forward or reverse pivoting causes the plate to move over the start button and prevents starting in other than neutral. The start button may be located such that the vertical lever moves over button in forward and a projecting plate moves over the button in reverse.