Agilent Technologies, Inc.

Hewlett-packard Company

Hubert Kuderer

Christian Buettner

Detlev Hadbawnik

Konrad Teitz

Stefan Rohrer

A Method of correcting a multi-path absorbance measuring system is suggested. The multi-path absorbance measuring system has a plurality of n measuring path: The method is executed by correcting the signal of the measuring paths based on a determined linearization function.

Multi-path flow cell correction

A method for processing measuring data and a device to perform the method, wherein the measuring data can be determined by using a measurement system, more particularly a chromatographic analyzing system, for the measurement of measuring values that correspond to certain information about, or of, a technical process and that depend on at least two variables.

Procedure for processing measuring data and device to perform the process

A method of reducing the effects of varying environmental conditions on a measuring instrument includes thermally insulating a measuring unit such that the effects of variations of environmental conditions on selected components of the measuring unit are substantially reduced, while allowing dissipated heat generated within the measuring unit to leave the measuring unit. The method also includes controlling a first temperature in the measuring unit by means of a control loop which includes a temperature sensor and means to influence the first temperature in the measuring unit in such a way that temperatures at locations with selected components are kept substantially constant.

Method of reducing the effects of varying environmental conditions in a measuring instrument and measuring instrument using the method

The invention concerns a method and device to carry out the method to provide quality control for a photosensor, especially a photodiode array, whose output signal depends on the intensity of an input signal formed by electromagnetic waves. The photosensor to be tested receives stimulation signals forming the input signals while the stimulation signal intensity of the stimulation signals is varied. The associated output signals of the photosensor to be tested are measured and recorded for evaluation purposes. The photosensor preferably receives at least two independently controllable, superposed individual stimulation signals with individual intensities. The different stimulation signal intensities of the individual stimulation signals are set with the aid of a controller coupled to stimulation signal source, and the output signals of the photosensor are measured and recorded using a measurement data recorder unit.

Method of and apparatus for testing a photosensor

In order to improve the noise performance of a charge balance type photodiode array by reducing error influences, e.g. due to offset voltages, flicker and/or thermal noise, on a desired signal a compensation circuit is inserted in each channel of this array. The basic concept under lying this compensation circuit is to effect a correlated double sampling method without any significant increase in space or power demand for the silicon chip of at least one channel of said photodiode array. Because the wanted signal is primarily an amount of charge, the compensating circuit comprises a switchable compensating capacitor to compensate an error contribution of the desired signal. In a first &ldquo;calibration period&rdquo; the compensating capacitor is charged or discharged in dependence on the actual noise contribution. In a second compensation period the compensation capacitor provides a voltage which is used to correct a predetermined reference voltage to insure compensation of the error contribution. These periods are synchronized to the charge balance technique used in connection with the photodiode array.

Charge balance type photodiode array comprising a compensation circuit

A charge balance type of photodiode array uses parallel A/D conversion in each channel of the photodiode array. The charge caused by the photocurrent of a photodiode in each channel is removed in predetermined charge packets provided by a dumping circuit and the binary encoded number of delivered charge packets corresponds to the actual photocurrent. Charge balance photodiode arrays have a wide variety of applications. It is therefore useful to adapt photodiode arrays to the specific requirements of an individual application. The intention therefore provides a photodiode array having at least one switching circuit to vary signal processing parameters such as a gain factor g or an attenuation factor k. This improvement facilitates a multifunctional photodiode array for a plurality of different applications.

Photodiode array with expanded dynamic range

Spectrometers often use a so called charge balance photodiode array. This type of photodiode array uses parallel AID conversion in each channel of said photodiode array, whereby a charge provided by a photocurrent is accumulated at an integrator circuit, and a dumping circuit removes this charge by well defined charge packets to keep the system in balance. In order to expand the field of application of these photodiode arrays, a storage circuit is inserted to buffer a possible charge overflow caused by a light beam of high intensity, as often occurs when flash light lamps are used in the spectrometers. The storage circuit includes a capacitor, and a current limiter which linearly conducts the photocurrent below a process limit defined by the saturation limit of the dumping circuitry and which, above this limit, converts a photocurrent pulse into a constant overflow current having a duration corresponding to the amplitude of the photocurrent pulse.

Photodiode array having a controllable dumping circuitry

A photodiode array comprises a plurality of n channels, each channel having a photodiode which is reverse biased such that it acts as a current source. Each channel further comprises an A/D converter for providing a digital output signal (DATA) which is representative o the photo current (Iph) provided by the photodiode and therefore of the intensity of the light impinging on the photodiode. The A/D converter comprises a controllable current source, an integrator circuit, a comparator for comparing the output signal (Vout) of the integrator with a predetermined signal (Vthreshold), a logic circuit for controlling the current source in response to the output signal (Vcomp) of the comparator such that Vout is kept within a certain range. Preferably, the current source provides current in the form of charge dumps to and/or from the integrator. The number of dumps in one direction is counted by a counter and is a digital measure of the photo current (Iph). The photodiode array is particularly useful in spectrophotometers since the provision of a separate A/D converter for each channel allow simultaneous processing of all the photosignals in the array so that spectra distortions arising from time delays in processing the photosignals are avoided.

Photodiode array

A photodiode array spectrometer for determining the spectral composition of a polychromatic beam of radiation comprises an array of photosensitive elements intercepting different wavelengths of the polychromatic beam of radiation. An output signal representative of the charge accumulated by a charge amplifier circuit is obtained each time a predetermined number greater than 1 of photosensitive elements is scanned such that the output signal is representative of the integral of a plurality of the amounts of radiation intercepted by a corresponding plurality of the photosensitive elements.

Method for operating a photodiode array spectrometer and photodiode

A photodiode array spectrometer comprises an arry (40) of photosensitive elements for receiving a beam of light. Light impinging on a photodiode causes discharging of the associated capacitors. The capacitors are recharged periodically by a charge amplifier via a video line (30) by closing transfer switches (SW1, . . . , SW 768) associated with the photosensitive elements, repectively. The switches are group together in several segments which are independently addressable such that during a recharge scan only selected groups of photodioldes are recharged. The information which segments are to be sctivated, i.e. which groups of switches are to be closed, is contained in a segment control block (43). An integration control block (46) additionally permits to adjust the time intervals between successive recharge cycles separately for each selected segment. The invention permits to select regions of interest of the photodiode array for a specific application, whereas other regions are ignored for that application, leading to a reduced data rate with high spectral resolution and sensitivity.

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Waldbronn, Germany

Hubert Kuderer