Abstract: A method and apparatus for suppressing loss of scale image contrast due to interference effects from optical path length differences, including lens profile aberrations, are provided in a displacement sensing optical encoder that uses a telecentric imaging configuration. According to the invention, the encoder is configured such that the image light that reaches the detector comprises symmetric ray bundles concentrated symmetrically on opposite sides of the optical axis center at the limiting aperture of the telecentric imaging configuration. Central ray bundles, and/or other ray bundles that have an optical path lengths significantly different than the operational symmetric ray bundles are prevented or blocked. As a result destructive interference is prevented and image contrast is improved.

Abstract: A position sensing device comprises a light source that radiates diffuse source light along an optical axis direction to a detector, and a moving aperture arrangement positioned between the source and detector, to move perpendicular to the optical axis direction. The moving aperture arrangement comprises first and second limiting apertures, which angularly filter and transmit the diffuse source light to form a measurement spot on the detector. At least one signal output by the detector is indicative of a position of the movable member along a measurement axis. The angular intensity distribution of the angularly filtered rays of light which form the measurement spot is more consistent as a function of position along the measurement axis than the angular intensity distribution of the source light. The resulting consistent intensity distribution within the measurement spot throughout the measurement range enhances measurement linearity and accuracy.

Abstract: A method and apparatus for suppressing loss of scale image contrast due to interference effects from optical path length differences, including lens profile aberrations, are provided in a displacement sensing optical encoder that uses a telecentric imaging configuration. According to the invention, the encoder is configured such that the image light that reaches the detector comprises symmetric ray bundles concentrated symmetrically on opposite sides of the optical axis center at the limiting aperture of the telecentric imaging configuration. Central ray bundles, and/or other ray bundles that have an optical path lengths significantly different than the operational symmetric ray bundles are prevented or blocked. As a result destructive interference is prevented and image contrast is improved.

Abstract: An illumination configuration for imaging-type optical encoders is provided. The illumination configuration generates uniform brightness images of scales and two-dimensional structures when utilizing telecentric imaging optics in the encoder readhead. In one embodiment, a desirable uniform irradiance distribution is created across the field of view by illuminating with a collimated or quasi-collimated beam, but insuring that the illumination is sufficiently incoherent that potential self-images arising from periodic structures on the scale are suppressed. In one embodiment, the ratio of an effective emitter size to a focal length of the collimating lens falls within a selected range, so as to assure relatively uniform illumination across the field of view and still provide sufficiently incoherent illumination.

Abstract: An optical analyzer with a configuration particularly suitable for use with planar liquid sample flow cells is provided comprising a polarized light source and at least two large angle scattered light photodetectors positioned respectively at acute, and right or oblique angles to the incident light beams. Differences in intensities of light measured at the two photodetectors are used to quantify components of the sample.

Abstract: An optical analyzer with a configuration particularly suitable for use with planar liquid sample flow cells is provided comprising a polarized light source and at least two large angle scattered light photodetectors positioned respectively at acute, and right or oblique angles to the incident light beams. Differences in intensities of light measured at the two photodetectors are used to quantify components of the sample.

Abstract: The present invention provides a flow cytometer made of two components: a flow cytometer optical head and a disposable flow module. The flow module utilizes a V-groove flow channel micromachined in a silicon wafer. The optical head comprises a laser to provide an illuminating beam and small and large angle photodetectors. Anisotropically etched facets of the V-groove reflect the illuminating beam. Small angle scattered light is also reflected by the V-groove wall and is collected by the small angle photodetector. Large angle scattered light and fluorescent light can exit the channel without reflection and are collected by the large angle photodetector. In addition, fluorescent light can be back-reflected by the V-groove, which enhances the collection efficiency.