numeric aperture

nu·mer·ic ap·er·ture (N.A.),

defined by the formula n sine a, where n is the refractive index of the medium between the object and objective lens and a is the angle between the central and the marginal rays entering the objective.
References in periodicals archive ?
One Receiver Photo Detector, Analog& Digital Drives and AC Amplifiers, Fourth Order butter worth 304 KHz Low pass Filter, Functional Generator on kit 1 Hz to 10 KHz sine wave, square wave(TTL), PC to PC serial link RS232C, PMMA Plastic Fiber & Gl/MM Glass fiber, Numeric Aperture Measurement jig, Mandrel Manual & Set of patch cords, In Built Power supply,etc...
"To fully optimize the system, there is an dectrically-conductive thermal control coating on the outer surface of the FCS2 microaqueduct slide, thus adding thermal uniformity even during experiments with periods of no perfusion flow." With the addition of the Bioptechs Objective Heater system for high numeric aperture applications, the FCS2 has become the prime micro-environmental system for long-term time-lapse studies, such as those Latimer's lab performs.