Understanding the Physical Camera Parameters

The following page helps you understand how to define and use the different components of a Physical Camera sensor.

Speos Light Box

The Speos Light Box contains all the geometries related to the lens system (lenses, opto-mechanics, etc.) of the camera to be simulated.

Lens geometries imported from OpticStudio are compatible.

Warning: All geometries included in the Speos Light Box of a Physical Camera are considered as part of the sensor. That means, like every sensor, it has no impact on the light propagation. If you are willing to add a specific geometry in the project having an impact on the propagation, you must add it in the list of geometries of the simulation and you must make sure the geometry is not included in the Speos Light Box of the Physical Camera. For more information, refer to Physical Camera Sensor - Specific Cases.

Important Rules

The Light Box must follow three important rules to be correctly used by the Physical Camera sensor:

  • The axis system of the Light Box must be defined so the optical axis of the lens system follows the Z axis.

    The axis system is defined during the export of the Light Box.

  • The origin of the axis system must be located with a small offset (around 10 times the Geometrical Distance Tolerance from the first face geometry).

  • The Light Box cannot include:
    • 3D textures
    • geometries with the following optical properties:
      • fluorescent materials
      • materials with volumic scattering properties
      • grating surface properties
      • DOE/thin lens surface properties

Black-boxed Speos Light Box

You can use a black-boxed Speos Light Box in a Physical Camera sensor.

Black-boxing the Speos Light Box restricts the access to all the sources/geometries/optical properties details and protect the intellectual property. Other users will not be able to access the Speos Light Box content and how light propagates inside it.

*.OPTSequence file creation: when creating your *.OPTSequence file, if you use a black-boxed Speos Light Box, the simulation of the Physical Camera sensor generates an encrypted *.OPTSequence file. Therefore, the Sequence Detection tool is not accessible from Virtual Photometric Lab as the *.OPTSequence file is encrypted.

*.OPTSequence file usage in Physical Camera: once the encrypted *.OPTSequence file is generated, you can only use it with the Physical Camera containing the black-boxed Speos Light Box. Therefore, the Sequence Detection tool is not accessible from Virtual Photometric Lab as the *.OPTSequence file is encrypted (if layers are separated by sequence).

Sequence File

The *.OPTSequence file corresponds to the file that determines the different paths available that rays can follow.

In the Physical Camera sensor, you have the possibility to add or not a Sequence file.

Important Rules

  • The Physical Camera sensor is compatible with the Direct and Inverse simulations. However, the *.OPTSequence file depends on the simulation type. That means, an *.OPTSequence file generated with a Direct simulation can only be used as input in a Direct simulation. The same rule goes for the Inverse simulation.
  • An encrypted *.OPTSequence file is generated out of a Physical Camera if the Speos Light Box is black-boxed. Therefore, the encrypted *.OPTSequence file is only compatible with the Physical Camera containing the black-boxed Speos Light Box.

Without Sequence File

The Physical Camera sensor can be used without a sequence file. The Physical Camera sensor will then only benefit from the Aiming Area. The optimized propagation engine makes sure that launched rays are directed towards this area. Once rays interact with the aiming area, the propagation continues using the Monte Carlo algorithm.

When no sequence file is used, you can only set the Layer separation type to Sequence in the Irradiance sensor.

Note: Not adding a sequence file to a Physical Camera sensor allows you to generate the future sequence file to be added to the Physical Camera sensor afterwards.

For more details on how to create this sequence file, refer to Creating an *.OPTSequence File for a Physical Camera Sensor.

With Sequence File

To get the most out of the Physical Camera sensor simulation performance, you need to add a previously generated Sequence file. When a sequence file is added to a Physical Camera, rays aim to the Aiming Area, then propagate following the sequences saved into the sequence file (and not following the Monte Carlo algorithm).

Important: When inputting an *.OPTSequence file, the Physical Camera only keeps the sequences that enter the lens system from the first face of the system and exit the lens system from the last face of the system without exiting the lens system between the first and last faces.

For a better readability, in the Sequence Detection tool, the interactions before the lens system are not displayed.

The number of sequences followed is determined using the Number of sequences parameter.
  • You can create a sequence file for a one-source configuration. However, the drawback of generating a sequence file based on one source is that it highly depends on the light source and its position.

  • You can create a universal sequence file covering as many optical paths as possible. This way, you do not depend on a light source and its position, on the contrary, you can place light sources at different positions.

For more details on how to create this sequence file, refer to Creating an *.OPTSequene File for a Physical Camera Sensor.

Note: When an *.OPTSequence file is used in a Physical Camera, every generated simulation result filename (*.xmp, *.lpf, etc.) is suffixed with "_sequential".

Number of Sequences

Number of Sequences determines the number of sequences to play and provide into the *.xmp result file.

Number of Sequences is useful only if you add a sequence file as input of the Physical Camera.

Irradiance Sensor

The Irradiance sensor is a mandatory part of the Physical Camera.

The Irradiance sensor must follow three important rules to be correctly used by the Physical Camera sensor:
  • The Irradiance sensor must be positioned in the scene considering the lens system defined in the Light Box, which is usually placed in front of it.
  • The Integration type must be Planar.
  • Depending on whether you add a sequence file or not, the Layer type choice differs:

    • If you add no sequence file, you can only set the Layer separation type to Sequence in the Irradiance sensor.

      Important: Sorting the sequences per Relative energy or Peak value will influence the sequences order in the *.OPTSequence file to be generated. The choice depends on what you want to highlight.

    • If you add a sequence file, you can set any Layer separation type in the Irradiance sensor.

      Important: If you add a sequence file and you set the Irradiance sensor with the Layer separation type Sequence, another *.OPTSequence file will be generated which will consider only the Number of sequences (X) set in the Physical Camera. That means, you will only have the X first sequences in the Sequence Detection tool during a Stray Light analysis. Besides all interactions outside the optical system (meaning the Light Box and the Irradiance sensor) are not included in this new *.OPTSequence file to ease the analysis. Sorting the sequences per Relative energy or Peak value is ignored as the sequences in the new *.OPTSequence file will be order as the *.OPTSequence file input.
Figure 1. Example: Physical Camera sensor with Sequence file + Irradiance Sensor with data separated by source

Light Expert Compatibility

When LXP is On

  • If a Speos Light Box is used for the purpose of the *.OPTSequence generation (meaning when no *.OPTSequence generation is used as input of the Physical Camera yet), the simulation generates a *.lpf file.
  • If a black-boxed Speos Light Box is used for the purpose of the *.OPTSequence generation (meaning when no *.OPTSequence generation is used as input of the Physical Camera yet), the simulation generates a *.lpf file. The *.lpf contains no trace information inside the Physical Camera (Light Box + Irradiance sensor) as it is encrypted by the black-box option. However, the *.lpf displays the ray tracing part of the optical paths outside of the Physical Camera.
  • If a Physical Camera uses a Speos Light Box along with the *.OPTSequence file, the simulation generates a *.lpf file.
  • If a Physical Camera uses a black-boxed Speos Light Box along with the encrypted *.OPTSequence file, the simulation generates a *.lpf file. The *.lpf contains no trace information inside the Physical Camera (Light Box + Irradiance sensor) as it is encrypted by the black-box option. However, the *.lpf displays the ray tracing part of the optical paths outside of the Physical Camera.