Device and method for non-contact optical imaging of a selected surface area of a hand
A device and method for non-contact optical imaging of a selected surface area of a user's hand, wherein the surface area is actively guided in a non-contact manner into a target position with respect to an image capture unit. For this purpose, the device has a frame in which the hand is inserted, assuming an actual position, roughly related to the target position. In addition, the device contains at least one active means for localizing the respective actual position and an output unit via which feedback is given to the user and the user iteratively guides the surface area into the target position. Advantageously, the device and method are suitable for distinguishing a natural hand from an artificial hand.
1. A device for non-contact optical imaging of a selected surface area of a user's hand, comprising:
a housing in which an image capture unit containing a main camera with an optical axis and an illumination unit is accommodated,
a control and computing unit,
an output unit,
a frame arranged outside the housing and connected to the housing via a stand, said frame having edges delimiting a recess which is open on one side, is open frontally with respect to a user position of the user and in which the surface area is positioned by the user, assuming an actual position, said frame having arranged therein an object plane of the main camera with a depth of field region in which a target position for the surface area is located,
a first active localizing device for localizing the actual position in the axial direction of the optical axis and a second active localizing device for localizing the actual position in the radial direction of the optical axis,
wherein the second active localizing device comprises at least one first distance sensor radiating parallel to the object plane, or
the second active localizing device comprises two first light barriers which form a first light beam pair and, radiating in or parallel to the object plane, enclosing a non-zero angle with each other, are arranged with mirror symmetry to a line extending parallel to an insertion direction (R) of the hand and passing through the optical axis, or
the second active localizing device is a projector which is arranged on a side of the object plane facing away from the main camera and projects a pattern into the recess.
2. The device for non-contact optical imaging of a selected surface area of a user's hand according to claim 1 , wherein the second active localizing device comprises the at least one first distance sensor radiating parallel to the object plane.
3. The device for non-contact optical imaging of a selected surface area of a user's hand according to claim 1 , wherein the second active localizing device comprises the two first light barriers which form the first light beam pair and, radiating in or parallel to the object plane, enclosing a non-zero angle with each other, are arranged with mirror symmetry to a line extending parallel to an insertion direction of the hand and passing through the optical axis.
4. The device for non-contact optical imaging of a selected surface area of a user's hand according to claim 1 , wherein the output unit is a display.
5. The device for non-contact optical imaging of a selected surface area of a user's hand according to claim 1 , wherein the second active localizing device is the projector which is arranged on the side of the object plane facing away from the main camera and projects the pattern into the recess.
6. The device for non-contact optical imaging of a selected surface area of a user's hand according to claim 1 , wherein the output unit contains an ultrasonic generator suitable for generating haptically perceptible pressure points on a virtual plane corresponding to the target position in the axial direction.
7. The device for non-contact optical imaging of a selected surface area of a user's hand according to claim 1 , wherein the output unit contains a compressed-air generator with a planar arrangement of nozzles which are directed into the recess.