US 6,532,061 B2 · Measuring the velocity of small moving objects such as cells

Abstract

Frequency domain velocity measurements and time domain velocity measurements are made using light from cells or other objects. An optical grating is used to modulate the light from an object so that it has a frequency proportional to the velocity of the object. Depending upon the embodiment, the pitch of the optical grating is uniform or varying. The modulated light is detected and various signal processing techniques, such as a Fast Fourier Transform function, are used to indicate the velocity of the object. Preferably, the velocity measured is applied in determining a timing signal employed for synchronization of an image of the object and an detector signal in an optical analysis system that uses a time delay integration detector to determine characteristics of the object in response to light from the object.

Claims53

Dependent claims

A velocity measurement system for determining an indication of a velocity of an object passing through a field of view, comprising:

(a) an optical element disposed to direct light traveling from an object passing through the field of view along a collection path;
(b) at least one optical grating of substantially uniform pitch disposed in the collection path, said at least one optical grating modulating the light traveling along the collection path to produce modulated light having a modulation frequency proportional to a velocity of an object passing through the field of view;
(c) at least one light sensitive detector on which the modulated light is incident, said at least one light sensitive detector producing an electrical signal responsive to the modulated light;
and
(d) means for converting the electrical signal into a sequence of digital samples, and processing the digital samples in the frequency domain to determine the modulation frequency, the indication of the velocity being determined as a function of the modulation frequency.

2 more elements

An imaging system that determines an indication of a velocity of an object for use in determining at least one additional characteristic of an object, while there is relative movement between the object and the imaging system, comprising:

(a) a collection lens disposed so that light traveling from an object passes through the collection lens and is directed along a first collection path;
(b) a beam splitter that is disposed in the first collection path so that a portion of the light traveling from the object along the first collection path is diverted along a second collection path;
(c) an optical grating of substantially uniform pitch disposed in the second collection path, said optical grating modulating the light traveling along the second collection path, to produce modulated light having a modulation frequency proportional to a relative velocity between the object and the imaging system;
(d) a light sensitive detector disposed in the second collection path to receive the modulated light, said at least one light sensitive detector producing an electrical signal in response to the modulated light;
(e) means coupled to the light sensitive detector, for determining the indication of the velocity of the relative movement between the object and the imaging system as a function of the electrical signal, using a Fast Fourier Transform function, said means producing a timing signal as a function of said velocity;
(f) an imaging lens disposed in the first collection path, producing an image of the object;
and
(g) a time delay integration detector disposed in the first collection path to receive the image produced by the imaging lens, producing an output signal that is indicative of said at least one additional characteristic of the object, said time delay integration detector being coupled to the means for determining the indication of the velocity to receive the timing signal and producing the output signal by using the timing signal to provide a clocking function that synchronizes the time delay integration detector to movement of the image of the object over the time delay integration detector so that light comprising the image is integrated over time as the image moves over the time delay integration detector.

5 more elements

An imaging system adapted to determine an indication of a velocity and at least one additional characteristic of an object, from images of the object, while there is relative movement between the object and the imaging system, comprising:

(a) a light source that emits light that is incident on the object, illuminating the object;
(b) an optical element disposed to direct light from the object along a first collection path;
(c) a first beam splitter disposed in the collection path so that light that is scattered from the object is directed along a different path, while light that is emitted by the object continues through the beam splitter along the first collection path;
(d) a second beam splitter disposed in the first collection path so that a portion of the light traveling from the object along the first collection path is diverted along a second collection path;
(e) an optical grating of substantially uniform pitch disposed in the second collection path, said optical grating modulating the light traveling along the second collection path, to produce modulated light having a modulation frequency proportional to a velocity of the relative movement between the object and the imaging system;
(f) a light sensitive detector disposed to receive the modulated light, producing an electrical signal in response thereto;
(g) means coupled to the light sensitive detector to receive the electrical signal, for determining the indication of the relative velocity between the object and the imaging system using a Fast Fourier Transform function, producing a timing signal as a function of said velocity;
(h) a spectral dispersing element disposed downstream of the second beam splitter in the first collection path, said spectral dispersing element spectrally dispersing the light emitted by the object, producing spectrally dispersed light;
(i) an imaging lens disposed to receive the spectrally dispersed light, producing an image thereof;
(j) a cylindrical lens disposed to receive the light scattered from the object, said cylindrical lens having a central axis around which the cylindrical lens is curved, said central axis being generally orthogonal to a direction of the relative movement between the object and the imaging system, so that the cylindrical lens produces a scattered pattern image of the object along a direction that is substantially parallel to said central axis of the cylindrical lens;
and
(k) at least one time delay integration detector disposed to receive the image produced by the imaging lens, producing an output signal that is indicative of at least one characteristic of the object, and to receive the scattered pattern image produced by the cylindrical lens, producing a different output signal that is indicative of at least one other characteristic of the object, said at least one time delay integration detector being coupled to the means for determining the indication of the velocity of the relative movement between the object and the imaging system, said at least one time delay integration detector producing said output signals by using the timing signal for synchronization of said output signals with the image and the scattered pattern image over said at least one time delay integration detector.

9 more elements

An optical analysis system employed to determine an indication of a velocity of a relative movement between an object and the optical analysis system and to determine and at least one other characteristic of the object, comprising:

(a) a first collection optical element disposed so that light from the object is directed along a first collection path;
(b) a first light dispersing optical element disposed in the first collection path so as to disperse the light traveling along the first collection path, producing first dispersed light;
(c) a first imaging optical element disposed to receive the first dispersed light, forming at least one image from the first dispersed light;
(d) a second collection optical element disposed to direct light from the object along a second collection path different than the first collection path;
(e) a second light dispersing optical element disposed in the second collection path so as to disperse the light traveling along the second collection lens, producing second dispersed light;
(f) a second imaging optical element disposed to receive the second dispersed light, forming at least one image from said second dispersed light;
(g) a beam splitter that is disposed in one the first collection path and the second collection path, so that a portion of the light traveling from the object along said one of the first collection path and the second collection path is diverted along a third collection path;
(h) an optical grating having a substantially uniform pitch disposed in the third collection path, the optical grating modulating the light traveling along the third collection path, to produce modulated light having a modulation frequency proportional to the velocity of the relative motion between the object and the optical analysis system;
(i) a light sensitive detector disposed in the third collection path to receive the modulated light, said light sensitive detector producing an electrical signal in response to the modulated light;
(j) means coupled to the light sensitive detector to receive the electrical signal, for determining the indication of the velocity of the relative movement between the object and the optical analysis system using a Fast Fourier Transform function, producing a timing signal corresponding thereto;
(k) a first time delay integration detector coupled to the means for determining the indication of the velocity to receive the timing signal and disposed to receive said at least one image formed by the first imaging optical element, said first time delay integration detector producing a first output signal that is indicative of at least one characteristic of the object by integrating said at least one image formed from the first dispersed light over time using the timing signal for synchronization of the first time delay integration detector with the relative motion of said at least one image formed by the first imaging optical element;
and
(l) a second time delay integration detector disposed to receive said at least one image produced by the second imaging optical element, said second time delay integration detector being coupled to said means for determining the indication of the velocity to receive the timing signal and producing a second output signal that is indicative of at least one other characteristic of the moving object by integrating said at least one image formed from the second dispersed light over time using the timing signal for synchronization of the second time delay integration detector with the relative motion of said at least one image formed by the second imaging optical element.

10 more elements

Dependencies are inferred from the claim text.

Measuring the velocity of small moving objects such as cells

Life of this patent

Measuring the velocity of small moving objects such as cells

Life of this patent

Abstract

Claims53