Optical measuring device using optical triangulation

• US 7,616,327 B2
• Filed: 03/17/2006
• Issued: 11/10/2009
• Est. Priority Date: 03/18/2005
• Status: Expired due to Fees

• Current Assignee: Sagem Defense Securite (Safran SA)
• Original Assignee: Sagem Defense Securite (Safran SA)
• Inventors: Michelin, Jean-Luc
• Primary Examiner(s): Toatley, Jr.; Gregory J
• Assistant Examiner(s): Underwood; Jarreas C
• Application Number:
  US11/909,069
• Publication Number:
  US 20090141290A1
• Time in Patent Office: 1,334 Days
• Field of Search: 356600-640
• US Class Current: 356/623
• CPC Class Codes: G03F 9/7026 Focusing
• CPC Class Codes: G03F 9/7034 Leveling
• CPC Class Codes: G03F 9/7049 Technique, e.g. interferometric
• CPC Class Codes: G03F 9/7065 Production of alignment light, e.g. light source, control of coherence, polarization, pulse length, wavelength
• CPC Class Codes: G03F 9/7088 Alignment mark detection, e.g. TTR, TTL, off-axis detection, array detector, video detection

Abstract

An optical triangulation measuring device includes an emmiter that emits two alternating light beams with different wavelengths along the same path; a beam splitter; an optical separator that directs the alternating split beams towards the surfaces from which they are reflected; an optical combiner that collects the beams and directs them along a path; optronic sensors that receive two light images and to deliver a signal indicating the position of the energy barycenter a time synchronizer for the two alternating beams and the two images on the optronic sensors; and a processor for processing the signals from the optronic sensors in order to supply information relating to the position and inclination of the surface.

Claims

1. An optical measuring device using optical triangulation for measuring, relative to a plane reference surface (L) and in a direction substantially perpendicular to said reference surface, the distance (d) and the inclination in two directions of a surface (W) to be checked, which locally can be likened to a plane, and comprising:

light emitter means (8) suitable for emitting along the same path, with a given repetition frequency, two alternating light beams (F_L, F_W) in a first wavelength range (Δ

λ

_L) and in a second wavelength range (Δ

λ

_W), respectively;

beam divider means (9) suitable for generating, from each single incident beam (F_L, F_W), several separate parallel light beams (F′

_L, F′

_W), being at least three in number and distributed in a predetermined configuration;

an optical splitter (11) suitable for directing each of the incident light beams (F′

_L, F′

_W) in two different directions in relation to the two wavelength ranges (Δ

λ

_L, Δ

λ

_W) respectively, said optical splitter (11) being placed laterally relative to the reference surface (L) and to the surface (W) to be checked, so that the two output beams (F′

_L, F′

_W) are directed, along paths of substantially the same length, into respectively the reference surface (L) and the surface (W) to be checked, off which they undergo respective reflections (F″

_L, F″

_W) so as thereafter to converge on each other;

an optical beam combiner (12) suitable for collecting the two reflected beams (F″

_L, F″

_W) coming from the same incident beam and in directing them alternately along one and the same optical output path;

sensor means (14) for receiving each of said alternating output beams (F″

_L, F″

_W), said sensor means (14) comprising optronic sensors (15);

which are fewer than or the same in number as that of the multiple light beams,

which are placed in a configuration that is correlated with that of the multiple light beams in such a way that each optronic sensor (15) receives alternately two light images (16_L, 16_W) formed by the two alternate reflected beams (F′

_L, F′

_W) respectively and

which are suitable for delivering (at

     20) an output signal representative of the position of the energy barycenter of each of the two light images (16_L, 16_W);

synchronization means (17, 18) for establishing a temporal relationship between the two alternate beams (F_L, F_W) emitted by the light emitter means (8) and the two images (16_L, 16_W) respectively formed on the optronic sensors (15); and

means (17) for processing all of the signals delivered by the optronic sensors (15) in order to provide information about the position and inclination of the surface (W) to be checked relative to the reference surface (L).

2. The device as claimed in claim 1, wherein each sensor of the sensor means is a photosensitive sensor of the position-sensitive (PSD) type suitable for delivering two output signals representative of the position of the energy barycenter of each of the two light images received by the sensor.

3. The device as claimed in claim 1 wherein the signal processing means are suitable for supplying information about the best estimate of the distance and the best estimates of the two angles of inclination, respectively, of the surface to be checked relative to the reference surface.

4. The device as claimed in claim 1 wherein the light emitter means comprise:

at least one light source emitting a single light beam in a wavelength band encompassing said first and second ranges; and

an optical modulator suitable for isolating, in said single light beam, said first and second wavelength ranges alternately over time in a predetermined frequency cycle.

5. The device as claimed in claim 4, wherein the frequency of the cycle is between 1 and 10 kHz and preferably about 2.5 kHz.

6. The device as claimed in claim 1, wherein the light emitter means emit in the red and/or in the near infrared.

7. The device as claimed in claim 6, wherein said two wavelength ranges are the approximately 600-630 nm range in the case of the beam directed onto the reference surface and the approximately 670-1050 nm range in respect of the beam directed onto the surface to be checked, respectively.

8. The device as claimed in claim 1, wherein the beam splitter means comprise a screen which has at least three holes of predefined shape arranged in a predetermined configuration which is suitable for being illuminated alternately by said light beams.

9. The device as claimed in claim 1 wherein the optical splitter and the optical combiner are static optical components operating by refraction and reflection according to the wavelengths.