Abstract: A color wheel includes a carrier element, a filter group, and a connection component. The carrier element includes a first carrier, and a second carrier. The carrier element rotates around the central axial line. The first carrier has at least one aperture. The filter group has a transparent zone and a filter bonding zone. The filter group and the carrier element share the central axial line. The filter bonding zone has at least one concave zone. The combining component is simultaneously in the apertures of the first carrier and the filter bonding zone to fix the filter bonding zone of the filter group between the first carrier and the second carrier.

Abstract: The present invention provides a color wheel including a motor and a color filter module. The color filter module includes a first color filter having a first transmittance and a second color filter having a second transmittance that is smaller than the first transmittance. 50% of the first transmittance is corresponding to a first light wavelength and a second light wavelength that is larger than the first light wavelength. The second color filter and the first color filter have substantially same hues. 50% of the second transmittance is corresponding to a third light wavelength and a fourth light wavelength that is larger than the third light wavelength. The second color filter satisfies a first condition chosen from the third light wavelength being larger than the first light wavelength or the second light wavelength being larger than the fourth light wavelength.

Abstract: In a color wheel comprising plurality of color filter segments, one of the filter segments consists of a sector portion, and a circular core portion which is formed intergrally at the inner circumferential area of the sector portion, and which is located at the center of the wheel assembled. The inner circumferences of the remaining filter segments are fitted directly to the outer perimeter of the circular core portion of the one segment, whereby the geometric accuracy of the color wheel can be achieved. Also, the alignment process of the filter segments for preventing the color wheel from generating vibrations and noises at the time of spinning at high speed can be simplified or even eliminated thus preventing the number of manufacturing processes from increasing.

Abstract: A color wheel is disclosed having balancing groove. The color wheel includes a carrier, having a central axis about which it is rotated. An external surface and a periphery rotates along the central axis; a color filter plate shares a same central axis with the carrier, wherein an annular groove is disposed on the external surface of the carrier. The groove is shaped, for example in a wedge so that once a balancing substance such as epoxy is added into the annular groove to balance the color wheel, it becomes lodged therein after curing as the opening is smaller than the cured epoxy.

Abstract: Calibrating each of a plurality of driven optical filters. The color parameters of the driven optical filters are characterized for the individual optical filter. These color parameters are used as calibration data to calibrate more standard information.

Abstract: A color filter assembly. The color filter assembly rotates around a central axis and includes a first carrier, a second carrier, a protrusion and a color filter. The first carrier has a first contact surface and a first joining portion protruding therefrom. The second carrier has a second contact surface and a second joining portion connected to the first joining portion. The protrusion is disposed on the first or second contact surface. The color filter has an opening with the protrusion inserted therein such that the color filter is fixed between the first and second carriers.

Abstract: The present invention relates generally to the field of biochemical laboratory. More particularly the invention relates to the improved and more accurate instrumental features of equipment used as e.g. fluorometers, photometers and luminometers. The object of the invention is achieved by providing an optical measurement instrument where there is an interface (218, 223, 233a, 233b, 238) for a changeable optical module (240), and excitation and/or emission beam is guided through an aperture of the optical module. This allows performing various types of measurements by changing an optical module without a problem lenses becoming unclean due to manual handling of the optical modules. The invention also makes possible to achieve an accurate measurement location and area within a sample.

Abstract: A color wheel includes lens structures, which are formed on a surface of a substrate opposite to a surface having filter sectors, and which have curved surfaces formed at their abutting ends and positioned along a boundary between adjacent filter sectors. Light impinging on an area of the substrate corresponding to the boundary is deflected due to one of the curved surfaces so as to be surely guided into one of the adjacent filter sectors and to be duly dispersed into a predetermined color, whereby light can be efficiently utilized.

Abstract: The present application describes embodiments of a neutral density color wheel filter. According to one embodiment, a neutral density color wheel (100) includes an opaque coating (135) over one or more color segments (120, 130, 140, 150, 160, 170) with randomly placed transmissive regions (131). The transmissive regions (131) can be configured to substantially transmit incident light and the opaque coating (135) can be configured to substantially block or absorb the incident light. Alternatively, the transmissive regions (131) can be configured to substantially transmit the incident light. The color segments with opaque coating (135) and transmissive regions (131) substantially eliminate light recycling due to the reflection from the color wheel. The light transmission from the color wheel (100) is independent of the optics of a display system.

Abstract: A color wheel is fabricated with filter sectors formed on both surfaces of a substrate such that filter sectors adjacent to each other are disposed respectively on the top and bottom side surfaces of the substrate, whereby structures as means for demarcating each of the filter sectors can be shaped on the substrate at one time so that the adjacent filter sectors can be positioned with respect to each other with an accuracy of the demarcation of the structures without positioning masking jigs every time each filter is formed.

Abstract: A forensic light source uses a pair of filter wheels to achieve a combination of the characteristics of filters on different wheels and may include a housing which supports the light, filter wheels and other parts with shock absorbing members such as rubber washers or the like to achieve a shock resistant housing. A light source and a plurality of light filters are contained within the housing. The light source is powered by an external power supply, thus making the light source light weight.

Abstract: A method and apparatus for assaying a drug candidate with a biosensor having one or more sensing surface-bound biomolecules associated therewith are disclosed. The method comprises the steps of measuring the binding interaction between the drug candidate and the one or more sensing surface-bound biomolecules of the biosensor to obtain an estimate of at least one binding interaction parameter of the drug candidate, and then comparing the estimated binding interaction parameter against a mathematical expression correlated from binding interaction data associated with known drug compounds to determine an estimate of at least pharmacokinetic parameter of absorption, distribution, metabolism, or excretion (ADME) that is related to the drug candidate. The present invention allows for the simultaneous measurement of different pharmacokinetic parameters of the drug candidate, as well as an indication of the drug candidate's solubility, by use of a single analytical instrument.

Abstract: A method for adjusting an optical system of an energy beam apparatus by using a mark signal that is obtained by one-dimensionally or two-dimensionally scanning a mark on a sample with an energy beam. The mark has a one-dimensional or two-dimensional periodic structure. A first mark signal is detected by scanning the mark with a beam. The mark is set on the optical axis of the optical system. A second mark signal is detected by scanning the mark with a beam. The mark is located at a position that is deviated from the optical axis. A deviation of a deflection position is determined based on a phase difference between the first and second mark signals.

Abstract: A high intensity light projector for stage, architectural and similar applications includes a controllable image quality projection gate providing advanced visual effects. The projection gate, capable of selectively scattering or transmitting incident light, may be constructed of an array of scattering liquid crystal material in combination with infrared and ultraviolet reduction means which provide in the high intensity beam, a stable thermal environment by minimizing the absorption of light by the projection gate. Additional thermal efficiency is provided by supplemental cooling means. Color control is also provided in the form of dichroic filter wheels forming cooperating adjustable low, high and band width filters including saturation control. A color measuring feedback sensor is also provided. An intensity measuring feedback sensor controls a spatially-modulated, variable-density, reflectively-coated dimming wheel. A programmable gobo system has provisions for gobo selection, orientation, and rotation.

Abstract: Methods and apparatus for generating multispectral images of tissue. The multispectral images may be used as a diagnostic tool for conditions such as cervical cancer detection and diagnosis. Primary radiation is produced with an illumination source. The primary radiation is filtered to select a first wavelength and a first polarization. Tissue is illuminated with the filtered primary radiation to generate secondary radiation, which is filtered to select a second wavelength and a second polarization. The filtered secondary radiation is collected with a detector, and a plurality of multispectral images of the tissue is generated according to different combinations of first and second wavelengths and first and second polarization with an analysis unit in operable relation with the detector. Apparatus utilizing the invention include endoscopes and colposcopes.

Abstract: A color wheel including a motor, a vibration damping element and a color filter. In this case, the motor has a housing and a motor body, and the housing is set at the central axis of the motor body. The vibrating damping element is set on the housing of the motor. The color filter is set on the housing of the motor, so that the vibrating damping element is positioned between the motor and the color filter. In addition, two other color wheels are provided.

Abstract: The present invention provides a method of detecting human antibodies in a sera solution. The invention also provides a method of quantitating anti-glycolipid antibody levels in solutions. The invention provides a method of diagnosing disease states, including neurological diseases, by quantitating a subject's antibody levels.

Abstract: The device for the pixel-by-pixel photoelectric measurement of a planar measured object includes projection means (3,21) for the imaging of the measured object (M) onto a two-dimensional CCD image sensor (22), filter means (66) provided in the imaging light path for the wavelength selective filtering of the measuring light impinging on the image sensor, signal processing means (23) for the processing of the electrical signals produced by the image sensor and for the conversion thereof into corresponding digital raw measured data (71), as well as data processing means (7) for the processing of the raw measured data into image data (72) representing the colors of the individual image elements of the measured object. Furthermore, illumination means (4,41-43; 5,51-53) are provided which include a Fresnel lens (42:52), which illuminate the measured object (M) with at least one essentially parallel light bundle under an angle of incidence ({acute over (&agr;)}) of essentially 45°±5°.

Abstract: A color measurement instrument capable of measuring both the nonpolarized spectral response and the polarized spectral response of a sample on a single reading. The instrument includes a source of polarized light to illuminate the sample, and a detector for measuring the light reflected by the sample. A rotatable filter wheel is located between the sample and the detector. Nonpolarizing bandpass filters and polarizing bandpass filters are mounted in the wheel in a circular configuration. A drive mechanism rotates the wheel to automatically sequentially align each of the nonpolarizing filters and the polarizing filters with the detector, enabling the instrument to sample both nonpolarized data and polarized data on a single reading.

Abstract: For determining the dependence of a first measuring quantity (Y) on a second measuring quantity (P) the second measuring quantity (P) is periodically modified with a frequency (f0). The first measuring quantity (Y) changing accordingly is measured. From the obtained measuring signal of the first measuring quantity (Y) the components of the first measuring quantity (Y) are determined with at least a plurality of frequencies. From the components thus determined the first measuring quantity (Y) is reconstructed for at least a plurality of values of the second measuring quantity (P) by signal processing.

Abstract: Photometric detector assembly which includes a housing, means for passing an optical beam along a path through the housing to a detector, a NIST traceable calibration filter enclosed within the housing, and means operable externally of the housing for moving the filter into and out of the beam path between calibration and normal operating positions.

Abstract: A classification apparatus, notably for uses in recognition or characterisation of odors, comprises a plurality of sensors for generating raw data representing a plurality of instances of a plurality of different classes; and a processing unit for processing said raw data so as to determine an identification model. The identification model comprises definitions of the classes and a particular allocation rule selected dependent upon the application. The class definitions are established by analysing data obtained during a learning phase, the analysis being performed according to a particular information extraction method. During a later identification phase, the identification model enables an instance of unknown class to be allocated to an appropriate class amongst those defined during the learning phase. The information extraction method can be selected dependent upon the application.

Abstract: Spectroscopic system and spectrometers including an optical bandpass filter unit consisting of a plurality of bandpass regions and a spatial encoding unit for encoding discrete frequencies of light passing through the optical filter. The incorporation of the encoding unit allows the spectrometer system to use a detector consisting of one or a small number of elements, rather than using a more expensive detector array as is commonly used with filter-based spectrometers. The system can also include an integrating chamber that collects the light that is not transmitted through the bandpass filter unit and is substantially reflected, and redirects this light to strike the filter unit again, resulting in a significant increase in the optical power passing through the filter. The integrating chamber maximizes the return of the reflected light to the filter assembly and minimizes optical losses.

Abstract: A multichannel system for synchronizing independently driven filter wheels. The system is comprised of a means for controlling operation of the system by providing appropriate instructions. A clock provides timing signals to assure that instructions are executed at the correct time. A device having a programmable memory with the ability to receive and transmit signals is in communication with the clock and the control means. This programmable memory device, in response to a signal from the control means executes a preselected program and transmits a signal in response to an instruction receive from the control means. Two assemblies, each comprised of a programmable motor controller, a motor driver and a motor are attached to an encoder and a filter wheel having a plurality of filters. The assemblies are connected to a power source.

Abstract: Described and claimed is a modular fluorometer and a method of using same to control an industrial water system, wherein said modular fluorometer comprises: one or more units with each unit comprising: a channel comprising an optically appropriate cell through which a water sample flows; a light source positioned outside said optically appropriate cell; an optional excitation filter positioned between the light source and the optically appropriate cell; a reference detector positioned outside the optically appropriate cell; an emission detector positioned outside the optically appropriate cell; an optional emission filter positioned between said emission detector and said optically appropriate cell; wherein if more than one unit is present in said modular fluorometer, said optically appropriate cells through which said water sample flows are aligned such that only one channel through which a water sample flows exists in said fluorometer.

Abstract: A color measuring system includes a color classifying apparatus and a color nonuniformity checking apparatus capable of measuring color nonuniformity which simplify the configuration, reduce cost, withstand mechanical vibration, and are capable of classifying the colors of objects well without limiting the light source even when its spectrum varies, and which are capaple of further improving the color classification accuracy.

Abstract: A device and method for performing spectral measurements in flow cells with spatial resolution using a variable transmission optical filter having at least two areas with different optical properties. Light from a light source passes through the variable transmission filter to a flow cell containing a sample to be analyzed. The resultant light pattern is sensed by a detecting means, which analyzes the spectral properties of the sample within the flow cell.

Abstract: A spectrophotometer providing a sample measurement area of selectable size. The spectrophotometer includes a sphere defining a sample station, a lamp to illuminate the interior of the sphere and therefore the sample station, a color measurement engine including an aperture directed toward the sample station, and a measurement area size selector. The size selector includes a movable plate defining two or more holes of different sizes. The plate can be moved so that only one of the holes is aligned with the aperture to control the size of the measurement area sampled by the color measurement engine.

Abstract: A portable spectrophotometer includes a rotating wheel provided with a plurality of filters having filter characteristics in the 400 to 700 nanometer wavelength range. The filters are moved between an optical conduit and a photoelectric sensor as the wheel is rotated. In one embodiment, a lamp housing contains three object illuminating lamps circumferentially spaced apart by 120.degree. and projecting light onto the object sample at a 45.degree. angle to the object sample. Light reflected from the object sample is conducted through the optical conduit and focused on the optical sensor by means of a focusing lens. A blocking filter is interposed between the lens and the wheel and serves to block light outside of the 400 to 700 nanometer wavelength range. A side sensor receives light from one of the three lamps through the filters as the wheel is rotated and provides output signals which are used as reference signals for the individual filters.

Abstract: Systems and methods are disclosed that optimize the combustion process in various reactors, furnaces, and internal combustion engines. Video cameras are used to evaluate the combustion flame grade. Depending on the desired form, standard or special video devices, or beam scanning devices, are used to image the combustion flame and by-products. The video device generates and outputs image signals during various phases of, and at various locations in, the combustion process. Other forms of sensors monitor and generate data signals defining selected parameters of the combustion process, such as air flow, fuel flow, turbulence, exhaust and inlet valve openings, etc. In a preferred form, a neural networks initially processes the image data and characterizes the combustion flame. A fuzzy logic controller and associated fuzzy logic rule base analyzes the image data from the neural network, along with other sensor information.

Abstract: A calorimetric apparatus includes an image pickup unit, an optical unit, a plurality of optical bandpass filters, a switching unit, an arithmetic processing unit, and an optimum filter selection unit. The image pickup unit picks up the image of light from a target object. The optical unit allows the light from the target object to form an image on the image pickup unit. The plurality of optical bandpass filters are arranged between the target object and the image pickup unit and have pass bands different from each other. The switching unit switches the plurality of optical bandpass filters. The arithmetic processing unit performs arithmetic processing for colorimetry on the basis of the spectrum data of the target object whose image is picked up. The optimum filter selection unit selects, from the plurality of optical bandpass filters, a filter suitable for colorimetry by the arithmetic processing unit.

Abstract: An electronic apparatus having an optical communication capability of the present invention has a casing 10 and optical filters 12 and 13 for screening an infrared beam emitting/receiving device 25. The optical filters 12 and 13 each has a particular screening characteristic. The filters 12 and 13 are selectively removably fitted in a beam input/output window 11 formed in the casing 10. With these filters 12 and 13, it is possible to use one of the filters 12 and 13 matching the varying environment, and therefore to intercept optical noise lying in a broad wavelength range.

Abstract: In an optical fittering device comprising at least two fitters, the first filter (EF1) is tilted by an angle of incidence whose value is adjusted to bring the cut-off limit of the first filter (EF1) closer to one of the sides of the line of the illumination beam (FLA), which reduces the optical density of the first filter, while the association in series of the first (EF1) and second (EF2) filters enables to obtain a high-pass filtering whose global density corresponds to the sum of the densities of the first and second filters and whose cut-off limit is lower than that obtained by a single filter tilted to its optimum angle. A third filter (EF3) mounted in parallel with respect to the first and second filters (EF1 and EF2) enables to obtain, at the level of the common collection path (TCC), a band eliminating filtering whose cut-off limits are positioned on either side of the illumination line with a view to an optimum analysis of the low frequency lines.

Abstract: The present invention relates to a rotary drum type optical filter apparatus, which comprises a filter unit for receiving an optical signal to spectralize the optical signal; a lens unit provided at the center of the filter unit for varying an optical path of the optical signal; and a driving device engaged with the filter unit for providing a displacement of the filter unit relative to the lens unit to obtain different spectrum colors of the optical signal.

Abstract: A multi-functional photometer includes a scanning mechanism having a housing that bears a movable linkage. The linkage is coupled to an optical scanning head and incorporates light-transmitting paths with at least one reflective surface for transmitting radiant energy to and from the scanning head. The arm comprises a C-shaped elbow member, pivotally attached to a shoulder member. In turn, the shoulder member of the arm is pivotally connected to the housing. In one embodiment the reflective surfaces are optically coupled and are mounted onto the housing, shoulder member and elbow member, such that the shapes of the light-transmitting paths remain fixed regardless of the orientation of the arm. The housing further incorporates a Cartesian-coordinate table for positioning the scanning head with respect to a microplate that contains a plurality of analyte samples.

Abstract: Apparatus for and a method of detection of light transmitted or reflected from a test object using any one of plural filters each with a unique center wavelength. To prevent chromatic aberration in non-collimated light passed through the filters, the thickness of each filter is unique, depending on its center wavelength.

Abstract: A multispectral imaging method and apparatus adapted for use in determining material properties, especially properties characteristic of abnormal non-dermal cells. A target is illuminated with a narrow band light beam. The target expresses light in response to the excitation. The expressed light is collected and the target's response at specific response wavelengths to specific excitation wavelengths is measured. From the measured multispectral response the target's properties can be determined.

Abstract: The invention relates to a method and apparatus for determining the concentration of at least carbon dioxide in a gas mixture on the basis of the absorption of infrared radiation (2), said apparatus comprising: a radiation source (1), the radiation emitted thereby being aligned to travel through a measuring cell (4) containing a gas mixture (6) to be analyzed; an optical band-pass filter (10), which is transmissive to a first wavelength band and positioned on the path of radiation emerging from the measuring cell or entering into the measuring cell through which the radiation passes; and a first detector (14), positioned in the radiating direction downstream of said first band-pass filter and used for detecting the radiation intensity falling thereon. Said optical band-pass filter (10) has a band-pass which lies within the wavelength range of 4.38 .mu.m-4.47 .mu.m for measuring the total concentration of carbon dioxide by means of the absorption spectrum of a molecule .sup.13 CO.sub.

Abstract: A spectroscopic system for measuring content of a constituent in a sample of a natural product is provided. The spectroscopic system includes a source for electromagnetic (EM) radiation and an absorbance filter for filtering EM radiation received from the source, where the absorbance filter transmits EM radiation of predetermined wavelengths solely by the absorbance characteristics of the filter material.

Abstract: Method of scanning register marks produced in multicolor printing which includes generating signals by means of at least one photoelectric receiver from register marks which are applied, respectively, in one color, in a register mark track on a print carrier transportable past the receiver, the register marks differing sharply in contrast with the ink on the ink carrier, determining in a circuit arrangement amplitudes of the signals from the register marks, and bringing a filter arrangement into a radiation path between a light source and the receiver for contrast matching, further includes automatically bringing one defined color filter of the filter arrangement into the radiation path and, after scanning at least one group of register marks wherein all of the colors present in the print are contained, determining a scattering of intensity maxima of the signals generated from the register marks of the one group of register marks, the defined color filter automatically brought into the radiation path having a

Abstract: A color classification apparatus for classifying the color component of a target object includes an imaging optical system, an image pickup device, optical bandpass filters, a transmission wavelength selection unit, a storage unit, a read unit, and a correction unit. The image pickup device is arranged on the imaging plane of the imaging optical system. The optical bandpass filters are optically arranged upstream the image pickup device, and have a plurality of different selectable optical transmission wavelength bands. The transmission wavelength selection unit selects one transmission wavelength band from the plurality of optical transmission wavelength bands.

Abstract: Measurement device, for the colorimetric measurement of a display screen. The device includes a first lens which forms the image of the Fourier transform of the elementary surface to be measured. An optical system is used to form a second lens which projects the image of the transform onto a set of detectors. The second lens (10) comprises an input lens (11) after the image plan (Fi) of the first lens (1), a colour filter (12) formed by filters (12l) which are associated with each colour, an output lens (13), downstream of the colour filter (12) for focusing the beams onto the detectors (7i, J) of the sensor (7), and a processing circuit (18).

Abstract: A LCD test system is able to adjust the differences in focal point lengths caused by chromatic aberration without increasing the size of the camera system and its manufacturing cost. In addition to the conventional structure, the parallel plates are inserted in the pockets of the rotation plate along with each of the four types of optical filters such as red, green, blue and transparency. Therefore, the differences in the focal point lengths due to the chromatic aberration are adjusted without increasing the size of the camera system and its manufacturing cost drastically.

Abstract: Automated measurement apparatus and methods for automated drug screening and for studying ion channel and cell surface receptor activity are provided. The apparatus is designed to initiate and measure rapid or transient events, such as cell receptor and/or ion channel activity. The apparatus can effect measurements of transient reactions in or more samples in a multi-well container, initiate the reaction with reagent addition and measure a resulting attribute of the sample for a period of time. The apparatus is capable of substantially continuously measuring and recording data corresponding to the measured attribute before, during and after initiation of the reaction so that a time course of the rapid or transient event is determined. Automated drug screening methods and methods for studying receptor and ion channel activity using the apparatus are also provided. The drug screening assays identify compounds that activate, inhibit or potentiate cellular ion channel or receptor activity.

Abstract: A detection system for use in an aircraft which is able to monitor atmospheric conditions ahead of the aircraft, generate an alarm signal if adverse atmospheric conditions exist ahead of the aircraft and generate information which indicates the position of the adverse conditions so the adverse conditions can be avoided. The system is able to detect the presence of volcanic ash cloud ahead of the aircraft and, if desired, can also be used to detect a high density of sulphur dioxide gas and/or clear air turbulence ahead of the aircraft. The system monitors infrared radiation received by the aircraft, generates intensity signals representative of at least one predetermined wavelength of the radiation and compares intensity signals with reference signals or intensity signals of another infrared wavelength.

Abstract: A digital color scanner capable of high color quality includes a light source, a photosensor, a first color filter, a second color filter, a third color filter, and a fourth color filter. The first, second, and third color filters are positioned in an optical path between the light source and the photosensor so as to enable the photosensor to produce a first, second, and third set of color image data during a first calibration scan. The fourth color filter is moved into and out of the optical path between the light source and the photosensor so as to enable the photosensor to produce a fourth, fifth, and sixth set of color image data during a second calibration scan. A circuit produces a set of color correction values from the first, second, third, fourth, fifth, and sixth sets of color image data.

Abstract: A spectrometer system includes a processing center, an underwater remote sensor and a communication link coupled therebetween. The sensor is deployed to at least partially penetrate a sediment layer disposed beneath a body of water. The sensor includes a window defining a sediment window plane through which a profile of the sediment layer is observable and a camera, an image plane of which is a conjugate of the window, the camera imaging light from objects in the sediment window plane to generate imagewise data, the imagewise data being transmitted over the communications link to the processing center. The sensor also includes at least one removable cell disposed in the sediment window plane, each removable cell being comprised of a transparent solid material having a void therein, the void in each removable cell for holding a standard material corresponding to the respective removable cell. The sensor further includes a camera filter device having at least one camera filter.

Abstract: A device for illuminating forensic depositions or other evidence that simultaneously provides output in three bands, the visible, ultraviolet and infrared. By a sequential mounting and rotation in two independent axis of a large selection of wavelength and bandwidth filters, the invention provides a highly-focused illumination system easily adjustable by the operator to enable selection of particular frequencies and bandwidths for enhanced observation of forensic subjects.

Abstract: A fluorescence particle analyzer includes a flow tube through which particles marked with different fluorochromes pass from a first location to a second location. Emissions from the first and second locations are respectively imaged at respective first and second filter elements so that emissions that reach a photodetector from said first location are primarily filtered by the first filter element, while emission that reach the same photodetector from the second location are primarily filtered by the second filter element. The first filter element is selected to preferentially transmit emissions from a first fluorochrome at the expense of emissions from a second fluorochrome, while the second filter element is selected to preferentially transmit emissions from the second fluorochrome at the expense of emissions from the first fluorochrome.

Abstract: A variable filter spectrophotometer, for use with sample and reference; has a main member, a filter unit, a drive, a detector, a light distribution system, and a clamping circuit. The main member defines first and second beam paths, which are intersected by the filter unit. The filter unit has filtering and opaque portions. The filter unit is continuously movable relative to the beam paths in a repeating cycle from a first filtering relation in which the filtering portion is interposed in the first beam path and the opaque portion completely blocks the second beam path, to a first dark relation in which both beam paths are blocked, to a second filtering relation in which the filtering portion is interposed in the second beam path and the first beam path is completely blocked, and to a second dark relation in which both beam paths are completely blocked. The filtering portion is variably transmissive along a direction of movement of the filter unit.