JPH0332641A - Laser doppler imaging device - Google Patents

Abstract

PURPOSE:To obtain a Doppler image at a high frame rate and with high sensitivity by decomposing the surface to be measured into many pixels of a two-dimensional array, obtaining a Doppler component in each pixel, accumulating its result, and converting it to an image. CONSTITUTION:A Doppler component contained in a light beam from the irradiated surface A is extracted and inputted to a base of a transistor Q1 of a circuit layer 5c. The Doppler component amplified by a negative feedback amplifier by the transistors Q1-Q3 is brought to low cut again by a capacitor C2, detected by a diode D1 and a transistor Q4, converted into a signal corresponding to a pixel value, and accumulated in a capacitor C4. A multiplexer M reads out the signal accumulated in the capacitor C4 at a prescribed timing, and sends it out to a controller. The capacitor C4 is cleaned whenever the signal is read out. The controller 6 generates a video signal by converting a pixel value from a photodiode arrayed two-dimensionally into luminance or hue information, and outputs it to a display 7. In such a way, in the display 7, a Doppler image is displayed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a laser Doppler imaging device, and particularly to a blood flow distribution image on a body surface, a blood flow distribution image immediately below an interface in the body, an eye fundus blood flow distribution image This invention relates to a laser Doppler imaging device for dynamically observing images in real time.

[Prior art] As a conventional device of this type, for example, Japanese Patent Application Laid-Open No. 64-3793
There is a blood flow distribution display device disclosed in Japanese Patent No. 1.

This blood flow distribution display device irradiates a measurement target surface pointwise with laser light, extracts a blood flow component from scattered light from the irradiation point, and uses it as a pixel value at the irradiation point.

Then, the light deflection element is driven to move the irradiation point, two-dimensionally scan the surface to be measured, obtain a two-dimensional array of pixel values, and convert them into an image to obtain a blood flow distribution image.

[Problems to be Solved by the Invention] In the conventional blood flow distribution display device described above, an image is formed by moving the irradiation point on the measurement target surface two-dimensionally to collect westward information. Because it takes a long time to obtain the data, there is a problem that it is not possible to obtain a frame rate sufficient for dynamic observation in real time.

Therefore, an object of the present invention is to provide a laser Doppler imaging device that can obtain Doppler images at a frame rate sufficient for dynamic observation in real time.

[Means for Solving the Invention] A laser Doppler imaging apparatus of the present invention includes a laser light source that emits laser light, an irradiation optical means that irradiates the measurement target surface with the laser light in a westward direction, and a laser light source that emits laser light. an imaging optical means for forming an optical image of the irradiated surface; and a large number of optical means arranged two-dimensionally at the formation position of the optical image to convert the optical image into electrical signals for each of a large number of pixels in a two-dimensional array. a photoelectric conversion means, and a large number of Doppler filter means for extracting Doppler components from the electrical signals for each pixel,
A large number of detection means each detecting each extracted Doppler component to obtain a pixel value for each pixel, a large number of storage means that respectively accumulate the pixel values, and a large number of two-dimensional arrays for each of the accumulated pixel values. The device is characterized in that it is equipped with an image display means for converting into optical signals for each pixel to form a Doppler image.

[Function] In the laser Doppler imaging apparatus of the present invention, a laser beam is irradiated to the measurement target surface in a westward direction, and a light image of the irradiated surface is divided into two
It is captured as an electrical signal by photoelectric conversion means arranged in multiple dimensions. Then, Doppler components are extracted and accumulated for each photoelectric conversion means.

Therefore, the frame rate can be made sufficiently high.

Furthermore, sufficient sensitivity can be obtained depending on the accumulation time.

Therefore, a Doppler image that can be dynamically observed in real time can be suitably obtained.

[Example] Hereinafter, the present invention will be explained in more detail based on the example shown in the drawings. Note that this invention is not limited to this.

FIG. 1 is a block diagram showing the configuration of a laser Doppler imaging apparatus 1 according to an embodiment of the present invention.

In this laser Doppler imaging apparatus 1, the laser light source 2 is a He-Ne laser with a wavelength of 632.8 nm.
emits laser light.

The emitted laser light is spread to a predetermined solid angle by the irradiation lens 3, and is irradiated onto the measurement target surface S in a westward direction. A
indicates the irradiated surface.

The imaging lens 4 converts the optical image of the irradiation surface A into a three-dimensional IC.
It is formed on the photo-sensing layer 5a of No. 5.

A large number of photodiodes are two-dimensionally arranged in the photo-sensing device 5a.

A filter layer 5b in which a large number of Doppler filters corresponding to each photodiode are formed is provided on the back side of the photosensing layer 5a.

A circuit layer 5c is provided on the back side of the filter layer 5b, in which a large number of amplifiers, detectors, storage capacitors, and multiplexers corresponding to each of the photodiodes and Doppler filters are formed.

FIG. 2 shows the cross-sectional structure of the photosensitive layer 5a, filter layer 5b, and circuit layer 5c when focusing on one photodiode. Further, a circuit diagram is shown in FIG.

As shown in FIG. 2, a transparent sapphire substrate 11 is provided on the light-receiving surface of the photosensitive layer 5a, and then a photodiode 12 is provided. The back surface of the photodiode 12 is an electrode, and faces an electrode 15 with a dielectric layer 14 in between. Its electrode 15 is connected via a through-hole contact 16 to a base electrode 17 of the transistor. 21 is an insulating layer through which the wiring layer 20 passes. 22 is a semiconductor layer, n+
Layer 18, nine layers 19, and the like are formed to constitute transistors, diodes, and the like.

The transparent sapphire substrate 11 and the photodiode 12 constitute a photosensitive layer 5a, and the dielectric layer 1
A filter layer 5b is constituted by a capacitor formed by electrodes facing each other with electrodes 17 . Wiring layer 20. A circuit layer 5C is constituted by the semiconductor layer 22 and the like.

If shown as a circuit diagram, it would be as shown in Fig. 3. PD is a photodiode 12, and C1 is a capacitor formed by opposing electrodes with a dielectric layer 14 in between, which functions as a Doppler filter that extracts only Doppler components. That is, the Doppler component contained in the light from the irradiation surface A is extracted and input to the base of the transistor Q1 of the circuit layer 5c.

The Doppler component amplified by the negative feedback amplifier formed by transistors Q1 to Q3 is low-cut again by capacitor C2, and detected by diode D1 and transistor Q4.
is converted into a signal corresponding to the pixel value, and the capacitor C4
is accumulated in

The multiplexer M reads out the signal accumulated in the capacitor C4 at a predetermined timing and sends it to the controller 6 shown in FIG. Capacitor C4 is cleared each time a signal is read.

The controller 6 converts the pixel values from the two-dimensionally arranged photodiodes into brightness or hue information to produce a video signal and output it to the display 7.

In this way, the Doppler image will be displayed on the display 7.

In the laser Doppler imaging device 1, Doppler components are continuously detected in each pixel, and pixel values obtained from these Doppler components are accumulated.
The frame rate is high enough for human observation, and the sensitivity is also high enough. Therefore, it becomes possible to obtain Doppler images that can be observed dynamically in real time.

Other examples include one using a phototransistor instead of the photodiode 12, and one using a COD structure as a multiplexer.

[Effects of the Invention] According to the laser Doppler imaging device of the present invention, the surface to be measured is decomposed into a large number of pixels in a two-dimensional array, a Doppler component is obtained for each pixel, and the results are accumulated and imaged. Therefore, Doppler images can be obtained with high frame rate and high sensitivity. Therefore, it becomes possible to dynamically observe the fundus blood flow distribution, etc. in real time.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a laser Doppler imaging apparatus according to an embodiment of the present invention, FIG. 2 is a sectional view of a main part of a three-dimensional IC constituting photoelectric conversion means, etc., and FIG. 3 is a block diagram of a three-dimensional IC shown in FIG. It is a principal part circuit diagram of Dimensional IC. (Explanation of symbols) 1... Laser Doppler imaging device 2... Laser light source 3... Lens for irradiation 4... Lens for imaging 5... Three-dimensional IC 5a... Photosensing layer 5b. ...Filter layer 5C...Circuit layer 6...Controller 7...Display PD...Photodiode C1...Capacitor Dl...Diode C4...Capacitor. de

Claims (1)

[Claims] 1. A laser light source that emits laser light, and an irradiation optical means for irradiating the laser light over a surface to be measured;
an imaging optical means for forming an optical image of a surface irradiated with laser light; A large number of arrayed photoelectric conversion means, a large number of Doppler filter means for respectively extracting Doppler components from the electric signal for each pixel, and a large number of detectors that respectively detect each extracted Doppler component to obtain a pixel value for each pixel. means, a plurality of storage means for respectively storing said pixel values, and image display means for converting each of said accumulated pixel values into optical signals for each of a plurality of pixels in a two-dimensional array to form a Doppler image. A laser Doppler imaging device characterized by: