Abstract: A lens includes first and second opposing surfaces extending radially from an optical axis in an optical system for passing light received from an object. The lens includes a peripheral edge extending between the first and second surfaces. A portion of the peripheral edge has at least either a positive slope or a negative slope with respect to the optical axis. The positive or negative slope of the peripheral edge is configured to reduce glare from stray light received from the first surface. A portion of the peripheral edge may be shaped in a sawtooth pattern or an approximate sinusoidal pattern. The peripheral edge of the lens is also configured to direct light that is received from the object toward light traps which are disposed adjacent to the lens.

Abstract: An optical system includes an optical frequency discriminator having a light source of an optical input beam, and an optical bandpass filter having a bandpass filter range and the optical input beam incident thereon at a bandpass-filter angle of incidence and may be desirably be adjusted. The optical bandpass filter transmits a first transmitted beam of a bandpass-filter frequency band and reflects a first reflected beam. An optical second filter has an optical edge in the bandpass range of the bandpass filter and the first reflected beam incident thereon at a second-filter angle of incidence. The optical second filter transmits a second transmitted beam band and reflects a second reflected beam.