PT series patterns

Calibration and projection patterns for machine vision Download flyer

Any machine vision lens (either telecentric or not) shows some amount of distortion. In addition to barrel or pincushion distortion, changes in the view angle or misaligned components will affect the image symmetry and generate the so called thin prism or keystone effect.

Imaging and metrology applications often require to minimize distortion, which can be software-corrected by analyzing the image of a precision pattern whose geometrical features are well known. For this reason Opto Engineering offers chrome-on-glass patterns optimized for software calibration, featuring extremely high geometrical accuracy thanks to photolithography techniques. The range of available chessboard patterns is compatible with most Opto Engineering telecentric lenses.

Calibration patterns

Compatibility Mechanical specifications
Part number Compatible telecentric lenses Compatible CMPH pattern mounts Dimensions
width x height		 Thickness Active area
width x height		 Squares
width 		Dimensional accuracy
Part numbers ending in (mm x mm) (mm) (mm x mm) (mm) (µm) Get Quote
PT 004-009 004, 007 and 009 CMPH 004-024 33 x 26 3.0 15 x 13 0.20 1.29
PT 016-024 016, 024 CMPH 004-024 33 x 26 3.0 31 x 24 0.60 1.52
PT 036-056 036, 048 and 056 CMPH 036-056 66 x 52 3.0 64 x 51 1.35 1.9
PT 064-096 064, 072, 080, 085 and 096 CMPH 064-096 107 x 83 3.0 105 x 79 2.20 2.4
PT 120-240 110, 120, 130, 144, 172, 192, 200, 240 n.a. 229 x 229 3.0 208 x 208 4.00 3.7

Projection patterns

Part number Format Substrate Coating Geometrical accuracy Edge sharpness
µm µm
PT 0000 0100 L Line pattern borofloat glass dichroic mirror 50 50
PT 0000 0100 P Line pattern soda lime glass chrome 2 1.4
PT 0000 0200 L Cross pattern borofloat glass dichroic mirror 50 50
PT 0000 0200 P Cross pattern soda lime glass chrome 2 1.4
PT 0000 0300 L Stripe pattern borofloat glass dichroic mirror 50 50
PT 0000 0300 P Stripe pattern, 8 lines in projection area soda lime glass chrome 2 50
PT 0000 0400 L Grid pattern borofloat glass dichroic mirror 50 50
PT 0000 0400 P Grid pattern, 8 x 8 lines in projection area soda lime glass chrome 50 50
PT 0000 0400 P Grid pattern soda lime glass chrome 2 1.4
PT 0000 0500 L Edge pattern borofloat glass dichroic mirror 50 50
PT 0000 0500 P Edge pattern soda lime glass chrome 2 1.4
PTGR 050 050 P Grid pattern, 80 x 80 lines in projection area soda lime glass chrome 2 50
PTGR 050 100 P Grid pattern, 53 x 53 lines in projection area soda lime glass chrome 2 50
PTGR 050 200 P Grid pattern, 32 x 32 lines in projection area soda lime glass chrome 2 50
PTGR 050 450 P Grid pattern, 16 x 16 lines in projection area soda lime glass chrome 2 50
PTST 050 050 P Stripe pattern, 80 lines in projection area soda lime glass chrome 2 50
PTST 050 100 P Stripe pattern, 53 lines in projection area soda lime glass chrome 2 50
PTST 050 200 P Stripe pattern, 32 lines in projection area soda lime glass chrome 2 50
PTST 050 450 P Stripe pattern, 16 lines in projection area soda lime glass chrome 2 50
PTST 010 010 P Stripe pattern, 400 lines in projection area soda lime glass chrome 2 50
PTST 020 020 P Stripe pattern, 200 lines in projection area soda lime glass chrome 2 50
PTST 050 500 P Stripe pattern, 50/50 soda lime glass chrome 2 50

LTPRSM 3d pattern projection

Stripe patterns Grid patterns
PT 0000 0300 P
 PT 0000 0400 P
PTST 050 450 P
 PTGR 050 450 P
PTST 050 200 P
 PTGR 050 200 P
PTST 050 100 P
 PTGR 050 100 P
PTST 050 050 P
 PTGR 050 050 P

LTPR simple pattern projection

Photolitography patterns Laser engraved patterns
PT 00000 100 P
 PT 00000 100 L
PT 00000 200 P
 PT 00000 200 L
PT 00000 300 P
 PT 00000 300 L
PT 00000 400 P
 PT 00000 400 L
PT 00000 500 P
 PT 00000 500 L

Active area

 

Pattern engraving process

Projection accuracy depends both on the pattern manufacturing accuracy and lens distortion.

The edge sharpness of the projected pattern depends on both the lens resolution and the engraving technique: laser-engraved patterns (part numbers ending with a L) or photolitography-engraved patterns (part numbers ending with a P) can be chosen depending on the type of the application

 

Custom patterns

Custom-made patterns can be supplied on request.

A drawing with accurate geometrical information must be submitted (please refer to the instructions below).

CMPH pattern holders

Software calibration is accurate if pattern placement is accurate too. To do so, Opto Engineering offers specific pattern holders to easily and precisely mount each calibration pattern on its specific holding mechanics.

The pattern is assembled on a frame held by three magnets: this floating system allows for the adjustment of the pattern phase and for proper centering.