Baxter Travenol Laboratories, Inc.

Baxter Laboratories, Inc.

James H Macemon

Charles I Soodak

David L Lessner

Stephen G Hauser

James G Bruni

Rodolfo R Rodriguez

George M Coker, Jr

Charles E Hodgson

The input polarizer and the output polarizer of a spectrofluorometer are each mechanically identical except for the optical elements, and are constructed as modules which plug into a spectrofluorometer base. Each of the polarizer modules includes a polarizing filter that is rotatable and a self-contained motor drive for rotating the polarizing filter. Each of the motor drives comprises an electric motor mounted on the respective module, a pulley mounted on the respective module and rotatable with actuation of the electric motor, a loop coupling the pulley to the polarizing filter for rotation of the filter with rotation of the pulley, and means for enabling the filter to rotate exactly 90.degree. in opposite directions.

Modular motorized polarizers for a spectrofluorometer

The automatic range selection circuit is particularly useful with a photomultiplier tube linear microphotometer and includes an amplifier, adjustable and switchable impedances coupled between an input and an output of the amplifier for adjusting the gain thereof, two comparators for comparing the output from the amplifier with upper and lower reference voltage levels, an integrator for integrating the output of the comparators, and an analog control circuit responsive to the output signal level at the output of the integrator for controlling the amount of impedance coupled between the input and output of the amplifier thereby to automatically adjust the gain thereof.

Automatic range selection circuit

Cuvette positioning apparatus for use in a spectrophotometer adapted for comparing first and second material samples includes a carrier in which cuvettes to be alternately analyzed are arranged end-to-end. The carrier is reciprocated along a vertical axis to expose the cuvettes in alternation to the monochromatic beam of the apparatus. The rate of reciprocation is selected to avoid cavitation of the samples, and a sinusoidal drive arrangement increases the exposure time of the samples to the light beam and minimizes transit time for optimum measurement efficiency. Circuitry responsive to synchronizing signals derived from the drive arrangement is utilized to form an output signal indicative of the difference in measured characteristics between the samples.

Cuvette positioning device for optical analytical apparatus

Component for a spectrophotofluorometer

Spectrophotofluorometer

A high pressure xenon arc illuminator bulb having a sapphire window generates a broad band of ultraviolet, visible and infrared radiation extending from about 180 nanometers to about 2000 nanometers. The emitted radiation in the range from about 180 to about 200 nanometers, in passing through the oxygen in the air, causes the molecules of oxygen in the form O.sub.2 to recombine to produce ozone, O.sub.3. Ozone is toxic. In the invention, a lens barrel, which holds a sapphire condensing lens, is joined to the xenon arc illuminator bulb with a lighttight and also hermetic connection. Thus, the condensing lens is optically rigid with the illuminator bulb and the ozone formed within the lens barrel is not released to the ambient environment, even though its local concentration within the lens barrel becomes high. Furthermore, the ozone confined within the lens barrel acts as an absorption filter for all of the wavelengths in the 180 to 200 nanometer band which are capable of producing ozone. The ultraviolet and other radiation leaving the sapphire condensing lens therefore does not produce toxic ozone in the ambient environment.

Integrally focused low ozone illuminator

A rotary sample changer for a spectrofluorometer has a revolving turret base which can be indexed and which carries an interchangeable sample carrier. Different sample carriers accommodate test cells, test tubes and cuvettes of different sizes and shapes. The revolving turret base and the interchangeable rotary sample carriers are constructed of material having good thermal conductivity and rotate on a large stationary hollow axle which is thermostated by thermally controlled internal fluid circulation to act as a heat source or sink to the samples. Thus, the sample carriers can readily be interchanged without disturbing the plumbing by which the thermostatic fluid is circulated. The revolving turret base is detented at the stations to which it is indexed without kinematic ambiguity and without application of any cocking force. Two spring biased ball detents, symmetrically spaced 180.degree. about the axis of rotation, are provided. At the four index stations one ball catches on one of two indexing grooves spaced 90.degree. apart, while the other ball bears against a flat.

Constant temperature, multiple sample, rotary changer

In a recording spectrophotometer the ordinate of the plotter-scriber is controlled by the output of a photomultiplier while the abscissa of the plotter-scriber is controlled by a selectable mode manually adjusted controller. In one mode, the controller furnishes a time base signal of selected rate of change, so that the abscissa of the plotter-scriber varies with the passage of time in accordance with said rate of change. In aother mode, the controller furnishes a stepping signal of selected periodicity, for application to a stepping motor, which changes the wavelength adjustment of the spectrophotometer at a rate determined by the selected periodicity. The spectrophotometer furnishes to the plotter-scriber an analog voltge varying with the instantaneous wavelength setting of the spectrophotometer, so that the abscissa of the plotter-scriber correspondingly varies with the instantaneous value of the wavelength. A common manually adjusted digital setting means is used for adjusting either the said selected rate of change of the time base or the said selected periodicity of the stepping signal.

Digitally settable selective control for speed of wavelength scan or for

A system for plotting the total luminescence spectrum of a sample comprises a spectrofluorometer including excitation and emission monochromator stages having operating wavelengths dependent on applied stepping pulses, and an X-Y plotter having a marking pen synchronized for movement along X and Y axis with changes in the wavelengths of the monochromators. A control circuit generates pulses to incrementally step the emission monochromator and horizontally scan the marking pen. A level detection circuit monitors the output of the spectrofluorometer and activates the pen upon attainment of a desired contour level. Limit circuitry incorporated in the control circuit momentarily actuates the excitation monochromator following each horizontal scan to increase the excitation wavelength for the subsequent emission scan to complete the plot.

System and apparatus for contour plotting the total luminescence

The noisy amplified signal from a photoelectric device is passed through an electronic low-pass filter before having its direct current component read on a meter. The cut-off frequency of the low-pass filter is adjusted in known manner by rotation of a control knob, so as to suitably match the cut-off frequency to the noisiness of the signal with a view towards speeding up the stabilization of the meter reading. To overcome the sluggishness of the system, the same control knob is briefly pushed, thereby overriding the low pass control. The method of using the system to speed up meter reading is described.

Single knob rotary control of meter damping and push control of damping

A spectrofluorometer providing wavelength correction by means of an arbitrary function generator driven by a wavelength scanning element of the spectrofluorometer. The arbitrary function generator may be driven by the emission scanning monochromator to derive a wavelength-dependent voltage signal which is combined with the measure photomultiplier output to thereby provide a base-line compensated resultant output signal. Alternatively, the arbitrary function generator may be driven by the excitation scanning monochromator to derive a wavelength-dependent voltage signal which is combined with the output of a reference photomultiplier tube receiving part of the output of the excitation monochromator to derive an excitation-corrected reference signal which is in turn combined with the measure photomultiplier tube output signal to thereby provide an energy-corrected resultant output signal. An analog divider may be employed to divide this last-named resultant output signal by said excitation wavelength-dependent voltage signal to thereby derive a quantum-corrected fluorescence emission output signal. The arbitrary function generator has successive incremental wavelength range segments provided respectively with independently adjustable potentiometers to suitably shape the wavelength-dependent voltage signal curve.

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Glen Burnie, MD, United States of America

James H Macemon