Abstract: A sensor housing and cosine diffuser are provided for the detection and measurement of ultraviolet (UV) irradiance. The cosine diffuser has a tiered structure to efficiently receive and transmit incident light that passes over and/or through the sensor housing structure. The sensor housing structure can be configured to have an irregular, serrated, castellated, and or repeating prong and/or tooth sequence to form a cutoff comb, through which incident light is attenuated. The attenuation of light in turn reduces measurement error caused when too much or too little incident light, relative to the actual intensity and irradiance of ambient incident light, reaches and transmits through a cosine diffuser due to the variation of the zenith angle of incident light over the course of a day.

Abstract: A sensor housing and cosine diffuser are provided for the detection and measurement of ultraviolet (UV) irradiance. The cosine diffuser has a tiered structure to efficiently receive and transmit incident light that passes over and/or through the sensor housing structure. The sensor housing structure can be configured to have an irregular, serrated, castellated, and or repeating prong and/or tooth sequence to form a cutoff comb, through which incident light is attenuated. The attenuation of light in turn reduces measurement error caused when too much or too little incident light, relative to the actual intensity and irradiance of ambient incident light, reaches and transmits through a cosine diffuser due to the variation of the zenith angle of incident light over the course of a day.

Abstract: A retrievable well tool for use in a subterranean well conduit utilizes plural valving elements to establish a fluid bypass around at least one annular elastomeric sealing element in response to movement of a control mandrel. The annular elastomeric sealing element actuates slips carried on the tool to engage the conduit wall in response to a differential pressure across the sealing element. The fluid bypass established by movement of the control mandrel is accomplished prior to an effective disengaging movement being imparted to the actuated slip elements.