Optics intergrating sphere
2014-02-10 23:49:03

The openness of following case has been allowed by our clients with exception of key parameters, which is only 90% of complete design process.


Optics intergrating sphere is used in light curve test for light source like halogen lamp, LED and so on.

II. Steps and result

A.Optical lens

Use CODE V to design to guarantee CCD resolution

CCD2/3 inch , target surface 8.8(W)*6.6mm(H)diagonal line: 11mm Pixel: 800*600so the required lens resolution MTF: Center 50lp/mm@0.3, edge 30lp/mm@0.3. For fisheye lens, there is big distortion in edge field, and image height and field angle is linear relation.  In optimization design, we can ignore the big distortion of edge field, but limit it through actual light path.

Lens data as below:


                                                                                                           Chart No. 1 Lens data

1.  Set object plane in CODE V with radius at 254mm because the actual shooting target is imaging sphere.

2.  Set reflector mirror with diameter is about 1/8 of that of sphere, say, around 60mm. From the above data sheet, the semi-diameter of mirror is 27.3mm, while diameter is 56 which is near designing required.

3.  The subsequent optical system is triplet. In order to remove the chromatic aberration effectively, and make the device is suitable for different wavelengths of light source tests, the second one is bonded mirror, and thus all lens material are common domestic available.  Whole length of relay lens is 70mm; other data is: F 2.8, wavelength 400-700nm.

2D drawing as below:


                                                                                            Chart No.2

Resolution of optical system as below:


                                                                                           Chart No.3 MTF


From chart No.2, center: 50lp/mm@0.45, edge: 32p/mm@0.3, beyond requirement.

B. Mechanical part

CODE V only can be used in lens design but not for mechanical design and modeling, so we firstly output igs file with CODE V assistance, and then make basic mechanical design and modeling with 3D mechanical designing soft-ware CATIA. Diameter of sphere is 504mm, and thickness is 3mm.


                                                                           Chart No.4


Diameter of sphere is 504mm, and thickness is 3mm.

C.  Simulation part

To simulate with Lighttools as below:

1. Set the sphere and its bottom as dffuse reflection, and reflection coefficient is 20%.

2. Set first mirror of fisheye lens as reflector, and reflectivity is 95%.

3. Set the rest mirror as normal glasses

4.     Make lens cone and CCD surface as mechanical absorbing properties.

5.     Add acceptor to CCD surface

6.     Add light source Cree  XR7090WT-CW, white light in half-angle 100 °,power 46lm.