LASER LINE MODULE

1 . A laser line module for projecting a laser line onto a surface of a distant target object, particularly as part of a laser-line triangulation device for measuring a distance to said surface, the projected laser line having a laser line length, the laser line module comprising:

a laser diode configured to emit radiation in the form of a laser beam;

a beam-shaping optical arrangement; and

a micro-lens array comprising a multitude of microlenses and having a surface with a height profile (h), each point on the surface having a distance from an average height of the height profile (h) and providing a divergence (dh) for radiation passing through the micro-lens array at the respective point, which divergence depends on the relative height of the respective point,

a spatial light modulator provided between the beam-shaping optical arrangement and the micro-lens array, wherein

the laser diode and the beam-shaping optical arrangement are arranged and configured to guide the radiation along an optical axis of the laser line module onto the spatial light modulator; and

the spatial light modulator comprises a multitude of elements, each element being controllable to adopt a first state or a second state, wherein each element is configured, while adopting the first state, to let the radiation pass to the micro-lens array and, while adopting the second state, to prevent that the radiation passes to the micro-lens array.

2 . The laser line module according to claim 1 , wherein the radiation has a first polarisation and the spatial light modulator is an LCD element and comprises a polarizing filter, wherein the LCD element comprises a layer of liquid-crystal molecules, wherein the multitude of elements are a multitude of pixels, each pixel being controllable to adopt a first state or a second state, wherein each pixel is configured, while adopting the first state, to let the radiation pass through the polarizing filter to the micro-lens array and, while adopting the second state, to wherein:

each pixel adopts the second state when a voltage is applied to the respective pixel, and adopts the first state when no voltage is applied to the respective pixel; and/or

the polarizing filter is fixedly attached to the LCD element, particularly glued to the LCD element.

3 . The laser line module according to claim 2 , wherein at least one subset of the pixels is arranged relative to the micro-lens array in dependence of the height profile (h) in such a way that, when the pixels of the subset adopt the second state, the radiation is prevented from passing through the polarizing filter to a particular subset of points on the surface of the micro-lens array,

wherein, by controlling the at least one subset of pixels, a plurality of different laser line lengths are achievable without changing a distance between the laser line module and the surface of the target object.

4 . The laser line module according to claim 2 , wherein the pixels are grouped in at least two, particularly exactly two, pixel-groups that are controllable separately from one another,

a first pixel-group being a first subset of pixels that is arranged relative to the micro-lens array in dependence of the height profile (h) in such a way that, when the pixels of the first subset adopt the second state, the radiation is prevented from passing through the polarizing filter to a first particular subset of points on the surface of the micro-lens array; and

a second pixel-group being a second subset of pixels that is arranged relative to the micro-lens array in dependence of the height profile (h) in such a way that, when the pixels of the second subset adopt the second state, the radiation is prevented from passing through the polarizing filter to a second particular subset of points on the surface of the micro-lens array.

5 . The laser line module according to claim 4 , wherein the first subset of pixels and the second subset of pixels are arranged relative to the second micro-lens array so that, by controlling the first subset of pixels and the second subset of pixels, at least three different laser line lengths are achievable without changing a distance between the laser line module and the surface of the target object.

6 . The laser line module according to claim 3 , wherein all points of a particular subset of points have a similar distance from an average height of the height profile (h), in particular wherein all points of a particular subset of points

are positioned on slopes between two height maxima; and/or

have a relatively small distance from the average height.

7 . The laser line module according to claim 3 , wherein all points of a particular subset of points provide a similar divergence (dh), particularly a relatively high divergence.

8 . The laser line module according to claim 2 , wherein the laser line is projected with a first angular spectrum if each pixel adopts the first state and with a second angular spectrum if each pixel adopts the second state, wherein the second angular spectrum is less than 50% of the first angular spectrum, wherein:

the first angular spectrum is at least ±20°, particularly at least ±25°, and,

the second angular spectrum is less than ±10°, particularly less than ±8.5°.

9 . The laser line module according to claim 2 , wherein each pixel is configured, while adopting the first state, to polarize the radiation so that it passes through the polarizing filter.

10 . The laser line module according to claim 2 , wherein each pixel is configured, while adopting the second state, to polarize the radiation so that it does not pass through the polarizing filter.

11 . The laser line module according to claim 1 , wherein the polarizing filter:

is configured to reflect at least 75% of the radiation that does not pass through

the polarizing filter, particularly at least 90%, and

is arranged tilted relative to the optical axis, wherein:

no radiation is reflected in the direction of the optical axis; and/or

the laser line module comprises an aperture and/or a heat sink, arranged so that

the radiation is reflected in the direction of the aperture and/or heat sink.

12 . The laser line module according to claim 1 , wherein the beam-shaping optical arrangement:

is configured to focus the laser beam in a first direction and widen and collimate it in a second direction, and/or

comprises a collimator, a further micro-lens array, and a cylinder lens, wherein the laser diode, the collimator, the further micro-lens array and the cylinder lens are arranged and configured to guide the radiation along an optical axis of the laser line module onto the spatial light modulator, in particular wherein the collimator comprises an aperture slit for improving line thickness and depth of field of the laser line.

13 . The laser line module according to claim 1 , wherein the spatial light modulator comprises a second polarizing filter that is provided between the spatial light modulator and the beam-shaping optical arrangement to produce the first polarization.

14 . The laser line module according to claim 13 , wherein the second polarizing filter is fixedly attached to the spatial light modulator, particularly glued to the LCD element.

15 . A laser-line triangulation device for measuring a distance to the surface of a target object, the device comprising an image sensor and the laser line module according to claim 1 , the laser line module and the image sensor being arranged and oriented so that the laser line module projects a laser line into a field-of-view of the image sensor.

16 . A laser-line triangulation device according to claim 15 , configured for scanning the surface of the target object with the laser line projected by the laser line module.