Abstract: There is disclosed herein a cell assembly for a spectrophotometric analysis or detection of a substance within a small sample volume. The assembly includes a cell body with a small sample bore, along with windows engaging said body to allow radiation to pass through the sample bore and the windows. A sealing arrangement is provided for each window via a sealing washer which is loaded by two means. An inner portion of the sealing washer engages the window and is loaded by a first spring loaded assembly, such as a Belleville washer and plunger. An outer portion of the sealing washer is separately loaded by a ring pressed against the cell body.

Abstract: There is disclosed herein a cell assembly for use in spectrophotometric analysis or detection of a substance within a small sample volume, such as in a capillary sample cell. The assembly comprises a transparent lens having the shape of a ball, sphere or cylinder, referred to as a "ball lens," and which is placed in direct contact or close proximity to the exterior wall of the capillary cell. This lens and cell are mounted together, any may form a removable cell assembly. The small volume may be contained within the ball lens itself. The ball lens serves to concentrate and direct light into the capillary cell. The arrangement also significantly reduces the sensitivity to alignment of replaceable cells thereby permitting easier mounting and replacement of such cells.

Abstract: A servo amplifier for d-c servo motors which converts the error signal into pulses which are amplified in a saturating amplifier to drive the motor. Both the duty cycle and the repetition rate of the pulses vary with the error signal. At large error signals the duty cycle is 100 percent, i.e., "full on"; at small error signals the duty cycle is low and the pulses spaced far apart. As the system approaches balance the pulses become shorter and less frequent, and the motor slows. The circuit comprises a signal integrator which drives two comparators, one for positive signals and the other for negative. The integrator generates a ramp voltage in a direction opposite to the polarity of its input, and is reset automatically by reset pulses of controlled and variable length when a comparator set point is reached. The reset pulses are the pulses which are amplified to drive the servo motor. In this system, reducing the gain does not produce a widened dead band, but only increases the time required for rebalance.