EP2996548A1

EP2996548A1 - Method and device for a 3d measurement of the skin surface and skin layers close to the surface

Info

Publication number: EP2996548A1
Application number: EP14731152.6A
Authority: EP
Inventors: Mark Weber; Jürgen VALENTIN; Marcus Grigat
Original assignee: Mikroskin GmbH
Current assignee: NanoFocus AG
Priority date: 2013-05-15
Filing date: 2014-05-12
Publication date: 2016-03-23
Also published as: WO2014183860A1; DE102013008278B4; US20160081553A1; US9687154B2; DE102013008278A1

Abstract

The invention relates to a method for a 3D measurement of the skin surface and skin layers close to the surface using a confocal sensor which is arranged in a handheld device and which comprises an integrated color camera. A sensor head of the handheld device is moved towards the skin area to be examined by the operator, and a color image of the skin surface is captured. The sensor then automatically switches to a confocal operation in which an image stack is captured, wherein the image stack, which extends into the skin interior, consists of a plurality of confocal images that are generated by a simultaneous detection of all the pixels required for a complete image, and the entire region which extends axially into the interior of the skin is scanned layer by layer in the Z direction. An analysis is carried out after the measurement data is captured such that a 3D image of the topography of the skin is generated. Furthermore, sectional images of the skin and of a skin volume to a depth of multiple millimeters is calculated from the captured image stack, and the images generated in this manner are displayed on a monitor.

Description

Method and device for 3-D measurement of the skin surface and near-surface skin layers

The invention relates to a method for the 3D measurement of the skin surface and skin layers near the surface by means of a confocal sensor with integrated color camera arranged in a handheld device.

It is known that the confocal technique is used to measure the topography of the surface of materials in the industrial sector. From the biological field, confocal microscopy is also known, namely for the acquisition of sectional images of certain surfaces due to the high

Deep discrimination of applied technology, usually with fluorescent markers, is performed. In addition, it is known that infrared light can be illuminated in the skin structure and observed microscopically within it.

US 2010/0214562 A1 describes a device with the aid of which

Skin surface or skin layers close to the surface are scanned one after the other point by point to generate an image composed of these points.

A similar device is known from US 2007/0263 226 A1. In this case, pinhole-like modulator arrays are used, whereby for each measurement, for example, five points on the skin can be scanned simultaneously. Then the array is moved laterally and another five points are scanned. Both devices and the process conducted with you have the disadvantage that a rapid measurement is not possible, which is due to the required lateral scan and the other the weak light output. Thus, both known devices appear to be unsatisfactory in handling, since shaking is to be expected due to the slowness of the measurement and the lack of light.

In addition, in medicine tomographic procedures as well

Dotting method known to be able to perform investigations in the deeper area of the skin.

Tomographic procedures are complex and expensive. The

Dotting method, for example for the diagnosis of skin cancer has the disadvantage that carcinomas must be opened and thus an increased risk of further spread by scattering arises.

The invention has for its object to be able to carry out a process with a single device, with the help of both the skin surface in vivo

Three-dimensionally measured as well as in vivo, the structure of the skin can be determined a few millimeters deep, with the absorption rate and the

Luminous efficacy with the greatest possible avoidance of moving elements over the prior art is significantly increased.

The invention solves this problem by a method for 3D measurement of the skin surface and near-surface skin layers by means of a in a

Handset arranged confocal sensor with integrated color camera, the handset is approached with a sensor head by the operator to the examined body of the skin and a color image of the skin surface is recorded, after which the sensor is automatically switched to confocal mode, in which one of a variety of simultaneous capture of all for one

complete image required pixels generated confocal images existing in the skin inside reaching image stack is recorded and the entire axially into the interior of the skin reaching area is scanned layer by layer in the Z direction, wherein after the measurement data recording an evaluation such takes place, that a 3 D image of the topography of the skin is created, further calculated from the captured image stack sectional images of the skin and the skin volume in several millimeters depth and the resulting images are displayed on a monitor.

The object is further achieved by a device for carrying out the method, consisting of a arranged in a portable housing confocal sensor with a stationary microlens array, the confocal sensor having a monochromatic radiation source, further comprising a color overview camera with a white light radiation source, said the camera can be switched into the measuring path by means of a beam splitter, and both the camera and the confocal sensor are connected to a signal evaluation unit. This can be connected to an external monitor.

It is therefore a hand-held measuring head, which is placed on the skin surface and there within a few seconds

complete characterization, namely:

- Recording a color image

- Measurement of the 3-D structure of the skin surface

- 3 D image (contrast image) of the inner skin structure.

By means of the color overview camera integrated in the sensor and one

Monitor is first visited by a several millimeters wide field of view, the skin site in question. This is simplified by the very compact dimensions of the sensor head, whose dimension does not significantly exceed the measuring field size. This is done first with the help of visual

Observation of the sensor head brought to the desired location and then approached by means of the life color monitor image of the area to be examined. Since the image from the sensor head is sharp to a distance of a few millimeters (about 5 mm), it can be placed on the skin or moved a short distance above it. If the area in question is found, the sensor will be within less

Milliseconds switched to the confocal operation, which absorbs within a few seconds consisting of many hundreds of confocal images stack (typically 200 to 1000 images). In this case, an image for this stack is generated in each case in real time by the simultaneous use of a number of pixels required for the image by the use of a stationarily arranged microlens array. During image acquisition, a scanner located in the sensor ensures that the entire axial measuring range (Z direction) is traversed. Of the

recorded image stack consists of equidistant frames.

The use of a microlens array also has the advantage that it contributes to the compactness of the device in that it is also part of the optical system itself.

After the measurement data recording, there are three types of evaluation:

1. The position of the top (closest to the sensor head)

Reflexes is evaluated. This results in the 3 D topography.

2. It will be like the computer tomography sectional images through the

Skin structure laid. These can be analyzed in terms of structure and contrast.

3. The previously recorded color image is displayed as an overlay of the 3 D topography. Thus, striking pigmentations can be superimposed microscopically with the present 3 D topography.

By repeated recording, the measuring field can be automatically extended (see claim 2). After completion of the pile recording then follows a z. B.

Acoustic signal, which signals to the operator that a new laterally staggered batch recording can be driven. The different shots can then - similar to the stitching - be assembled into a complete picture. According to claim 4 it is provided that in addition to the evaluation described above by focusing on an interesting depth section

High-speed real-time image are generated, for. B. to measure the perfusion of special areas.

According to claim 6 it is provided that the confocal sensor has a matrix sensor in CMOS or CCD technology, as well as the color overview camera.

The confocal transmitter has a "look" inside the skin

monochromatic radiation source, in this case an infrared radiation source, which radiates in the range between 800 and 950 nm, wherein selected according to claim 8 as the measurement wavelength 850 nm or 940 nm.

The device according to the invention can be used in cancer diagnostics for the early detection, observation and diagnosis of changes. In addition, cosmetic effects can be observed, e.g. the penetration depth of cosmetic preparations as well as the depth effect of the treatment. It is also possible to determine the thickness and structure in the case of burn injuries or skin grafts, the results of the investigation being obtained within a few seconds thanks to the technique according to the invention by means of a single device.

The invention is illustrated and explained below with reference to FIGS. 1 and 2:

Show it:

Fig. 1 shows schematically the optical structure of the device according to the invention; 2 shows a more detailed illustration of the structure of the confocal sensor. FIG. 3 Flowchart of the measurement In the figure 1, the optical structure of the device according to the invention is shown schematically. It consists essentially of the groups A and B, wherein in group A the confocal measurement setup and in group B a digital color camera is shown.

The reference numeral 1 denotes the object plane (in this case, the skin surface). In the device itself is designated by the reference numeral 2, a focusing lens, which emitted by the collimated radiation source 13 monochromatic light (infrared) and that of the also collimated

White light source 12 originating light focused on the object plane 1. The light reflected from the object plane is imaged via a further focusing lens 4 and the microlens array 5 arranged in the intermediate image plane through the imaging optics 7, which consists of the elements 21, 22, 23 from FIG. 2, on a CCD matrix sensor 8 the beam splitter 3 and the imaging optics 10 on the

Matrix sensor 11 (camera).

The lens 4 is the only moving part of the assembly, since it is for the

Focusing is responsible for the layered image acquisition.

2, 5 is a rectangular or a square microlens array, which is arranged stationary in the beam path and allows a complete "slice image" to be recorded simultaneously in real time B. 30 μητι), wherein the lenses are typically arranged round and in a square or hexagonal packing.In the arrangement shown in Figure 2, which is a central component of the confocal measuring system, the light from the light source 13 from a collector lens 14 on a beam splitter 6 is projected as a parallel light onto the microlens array 5. The microlenses 5 produce many reduced images of the light source 5. The focusing unit 16 (reference numerals 2 and 4 of FIG

FIG. 1) depicts the foci of the microlenses on the object 19. The light reflected by the object 19 is focused on the previously described elements 16, 5 and 6 via the focusing optics 23 on the aperture 21 and directed via the lens 22 to the CCD sensor. The aperture diameter of the aperture 21 is chosen so that it corresponds to the emission surface of the light source 13.

In the group B is between the color camera 1 and a beam splitter 9 the

Focusing optics 10 arranged. About the beam splitter 9, the light of the white light radiation source 12 is deflected into the optical path of the confocal sensor A, where it is directed by means of the semitransparent mirror 3 (beam splitter) on the object plane 1 of the object 19.

FIG. 3 shows the time sequence of a measurement. Here, the mode 100 indicates that a recording of a life color image stream of the measurement object 19 takes place by means of the color camera (group B), the duration of this recording being user-controlled (overview image).

In mode 200, the camera mode switches to confocal mode. There is a fast confocal measurement with depth scan (indicated by the oblique course). In this case, the focal plane 1 is pushed through the entire volume of the measurement object 19.

This results in an overview of the image during the measurement

Skin surface, after which the 3 D topography of the surface of the skin is measured down to a depth of several millimeters by the confocal measurement.

By using an infrared light source can be during the confocal

Measurement can be seen inside the skin, wherein as indicated above, respectively by axial scanning a stack of images is generated. In the evaluation unit, not shown, the measured data in slice images of the skin (also in terms of volume) are calculated and displayed on an (external) monitor, also not shown.

In the further course (mode 100), a life color image can again be displayed, while in mode 300 confocal is finally focused to a specific depth and a stream of images is recorded. With the measurement in mode 300 z. B. in a certain depth, the blood circulation can be displayed in real time and / or evaluated.

Claims

claims

1. A method for 3D measurement of the skin surface and near-surface skin layers by means of a arranged in a handheld confocal sensor with integrated color camera, wherein the handset with a

The sensor head is approached by the operator to the point of the skin to be examined and a color image of the skin surface is recorded, after which the sensor is automatically switched to confocal mode, in which one of a plurality of confocal images generated by simultaneously acquiring all the pixels required for a complete image Inside the skin reaching inside the image stack is recorded and the entire axially into the interior of the skin reaching area is scanned layer by layer in the Z direction, wherein after the

Measurement data recording an evaluation is made such that a 3-D image of the topography of the skin is created, further calculated from the captured image stack sectional images of the skin and the skin volume in several millimeters depth and displayed images are displayed on a monitor.

2. The method according to claim 1,

characterized, that the measurement field is expanded by repeated recording and the individual recording stacks are combined to form an overall picture (stitching).

Method according to claim 2,

characterized,

that after completion of a batch recording, a signal for the operator to record the next image stack is made.

Method according to one of claims 1 to 3,

characterized,

that in order to generate a sectional image in real time, confocal focus is confocal to a specific skin depth and a continuous series (stream) of images is taken.

Apparatus for carrying out the method according to one of claims 1 to 4, consisting of a arranged in a portable housing

confocal sensor (A) with a stationary arranged microlens array (5), wherein the confocal sensor (A) has a monochromatic radiation source (13), further comprising a color overview camera (B) with a white light radiation source (12), wherein the camera a beam splitter (3) can be switched into the measuring path and both camera (B) and

Confocal sensor (A) is connected to a signal evaluation unit.

Device according to claim 5,

characterized,

in that the confocal sensor (A) has a CCD or CMOS matrix sensor (8) and also the color overview camera (B) has a matrix sensor (11).

Device according to one of the preceding claims,

characterized,

in that the radiation source (13) of the confocal sensor (A) is an infrared source emitting in the range between 800 and 950 nm.

Device according to claim 7, characterized,

the wavelength is 850 nm or 940 nm.