Abstract: A device for irradiating a limited, defined area where uniform and intense irradiation is obtained of a sharply defined light field (7) of variable size, the light from a halogen lamp (1) or similar incoherent light source being directed by means of an elliptical mirror (2) towards one end surface (3) of a transparent rod (4) whose opposite end surface (6) is thereby uniformly irradiated and is imaged by a lens (7) in the area (9) which has to be irradiated.

Abstract: A method for increasing the intensity of the excitation light, and thereby the sensitivity, of flow cytometers. The initial part of the signal produced by each cell as it enters the excitation focus triggers a current pulse to the excitation light source, with a duration approximately similar to the time required for the cell to pass through the focus. This current pulse, which is superimposed on the constant operating current to the light source, causes an increase of the intensity of the excitation light during the period when the cell is passing through the excitation focus and thereby an increase of the sensitivity of the flow cytometer.

Abstract: A system for filtering, purification, and recirculation of the sample carrier water in a flow cytometer. After running through the flow chamber of the flow cytometer, the water, including the sample, is passed through physical and chemical filters to remove cells, cell debris and other particulate matter as well as dyes, before the water is recycled through the instrument as carrying, or sheath fluid for subsequent samples.

Abstract: A liquid flow photometer for fluorescence light and/or scattered light measurement, having a measuring area (37) where particles (38) flow through. The device comprises a first objective (3) focussing excitation light (5) in the measuring area (37) and also collecting fluorescence light emanating from the measuring area (37). The first objective (3) is modified by a slightly transparent central stop (39) placed in the rear focal plane of the objective. The device further comprises a second objective (23) collecting the light falling within the conic sector (40) obscured by the central stop (39). This light contains partly scattered light and excitation light. The corresponding photo-electric signal is divided in a pulsed (AC) component and a constant or slowly varying (DC) component. The DC component serves to correct one or both of the AC components representing the fluorescence and scattered light intensity in order to make them independent of variations in the excitation light intensity.

Abstract: Device for liquid flow cytophotometer including a device for hydrodynamic focussing (4,6) of a cell- or particle-suspension towards a measuring area, and an optical excitation-and detection-system (9), preferentially based on oil immersion optics, characterized by the focussing device being formed at or in relation to the system's optical axis-rotating nozzle assembly (1) directed towards a surface (7) which is open in relation to the surrounding atmosphere and situated on the optics (9), forming the optics' measuring area, thus supplying a laminar liquid flow of the above-mentioned suspension.