Compensation of light intensity across a line of light providing improved measuring quality

Patent metadata

Field	Value
Publication number	US-10330466-B2
Application number	US-201615343173-A
Country	US
Kind code	B2
Filing date	Nov 3, 2016
Priority date	Nov 4, 2015
Publication date	Jun 25, 2019
Grant date	Jun 25, 2019

Abstract

Method of providing measuring light for triangulation-based distance measurement to an object to be measured, wherein distance information is derivable by detecting at least portions of the measuring light reflected at the object. The method comprises emitting light and shaping the light so that the measuring light is provided in form of a line having a midpoint and two opposite ends. The intensity distribution of the light across the line is adjusted so that a respective light intensity at the ends of the line is at least 10% higher than light intensity around the midpoint.

First claim

What is claimed is:

1. A method of providing measuring light, for triangulation-based distance measurement to an object to be measured, wherein distance information is derivable by detecting at least portions of the measuring light reflected at the object, the method comprising:
emitting light, and
shaping the light so that the measuring light is provided in form of a line having a midpoint and two opposite ends, wherein:
adjusting the intensity distribution of the light across the line so that a respective light intensity at the ends of the line is at least 10% greater than light intensity around the midpoint, and
shaping the light is provided by means of a first micro-lens array and a fast axis aperture stop.

2. The method according to claim 1 , wherein:
the intensity distribution of the light across the line is adjusted so that light intensity from the midpoint to the respective ends of the line increases:
according to an expected decay of intensity along the line due to an interaction with an optical element, in particular so that the expected decay is compensated and a signal amplitude on side of an detector provideable for receiving the line is basically constant along the received line, and/or

according to a factor proportional to

1

cos
n

⁡

(
α
)

,

wherein n is a positive integer and n<5, in particular proportional to

1

cos
3

⁡

(
α
)

,

1

cos
4

⁡

(
α
)

⁢

⁢
or
⁢

⁢

1

cos
5

⁡

(
α
)

.

3. The method according to claim 1 , wherein:
the intensity distribution of the light across the line is defined by defined diffusion of the emitted light with a particular diffusion angle α, wherein the midpoint defines a diffusion angle of α=0° and maximum diffusion angle values correspond to the respective ends of the line.

4. The method according to claim 3 , wherein: the light intensity increases with increasing diffusion angle values according to a factor proportional to

1

cos
n

⁡

(
α
)

,

wherein n is a positive integer and n<5, in particular proportional to

1

cos
3

⁡

(
α
)

,

1

cos
4

⁡

(
α
)

⁢

⁢
or
⁢

⁢

1

cos
5

⁡

(
α
)

.

5. A method for determining distances to an object to be measured based on the principle of triangulation, comprising:
emitting light,
shaping the light so that measuring light is provided in form of a line,
directing the measuring light to the object to be measured,
receiving measuring light reflected at the object to be measured,
directing the received measuring light to a sensor,
detecting the received measuring light by means of the sensor, and
deriving distance information based on the detected reflection, wherein:
the measuring light is generated and emitted in form of a line according to the method of claim 1 , wherein
the received measuring laser light reaches the sensor with a substantially uniform intensity distribution across the line, or
the received measuring light recorded by the sensor has a substantially uniform signal amplitude across the line.

6. A light emitting unit, in particular of or for a triangulation-based distance measuring device, for providing defined measuring light, in particular laser light, the light emitting unit comprising:
a light source for emitting light, in particular a laser light source for emitting laser light, and
a beam forming assembly for shaping the light by affecting propagation of the light emitted by the light source, wherein the beam forming assembly is arranged and designed so that measuring light is provided in form of a light line having a midpoint and two opposite ends, wherein:
the light source and the beam forming assembly are arranged and designed so that an intensity distribution of the light across the line is adjustable such that a respective light intensity at the ends of the line is at least 10 % greater than light intensity around the midpoint, and
the beam forming assembly comprises a first micro-lens array and a fast axis aperture stop.

7. The light emitting unit according to claim 6 , wherein:
the beam forming assembly is arranged and designed so that the intensity distribution of the light across the line is provided so that light intensity increases from the midpoint to the respective ends of the line:
according to an expected decay of intensity along the line due to an interaction with

Assignees

• Hexagon Technology Ct Gmbh

Inventors

• Kipfer Peter
• Stigwall Johan
• Jensen Thomas

Classifications

• G02B19/0009

  having refractive surfaces only · CPC title

• G01B11/2518 Primary

  Projection by scanning of the object · CPC title

• G02B27/0966

  Cylindrical lenses (cylindrical lenses per se G02B3/06) · CPC title

• G02B19/0052

  the light source comprising a laser diode (coupling into light guides using intermediate optical elements G02B6/4204; semiconductor lasers having optical devices external to the laser cavity H01S5/005) · CPC title

• G02B27/0927

  Systems for changing the beam intensity distribution, e.g. Gaussian to top-hat · CPC title