Micro Electro Mechanical System (MEMS)
This object simulates a Micro Electro Mechanical System (MEMS). The MEMS consists of an array of small rectangular mirrors (commonly called pixels). The mirrors may tip at any of three angles, each rotated about an axis to point the mirror in any direction. The mirrors may be turned on and off by rows, by columns, or by individual mirrors if desired to model any state the MEMS can be in. This type of device is sometimes called a Digital Mirror Device (DMD). The following parameters are used to define the MEMS:
| Parameter # | Description | Face Name | Face # |
| 1 | The number of X pixels across each row. | All Faces | 0 |
| 2 | The number of Y pixels down each column. | All Faces | 0 |
| 3 | The full X width of the array in lens units. The X pixel width is this number divided by the number of X pixels. | All Faces | 0 |
| 4 | The full Y width of the array in lens units. The Y pixel width is this number divided by the number of Y pixels. | All Faces | 0 |
| 5-7 | The tip angle of the pixel when in state 0, 1, or 2. The element tips about the X axis if Parameter 8 is zero. Positive angles tilt the element counterclockwise in the Y-Z plane, when the +X axis faces into the page / away from the observer. | All Faces | 0 |
| 8 | The rotation angle around the Z axis about which the pixel will tip. The rotation is counterclockwise in the X-Y plane, if the Z axis faces out of the page / toward the observer. | All Faces | 0 |
| 9 | P-Flag. If this value is 0, then the pixels are addressed by rows. If 1, then the pixels are addressed by columns, and if 2, the pixels are addressed individually. | All Faces | 0 |
| 10 | Integer values which define the state of the rows, columns, or pixels, as described below. | All Faces | 0 |
Elements in the MEMS object are numbered starting in the bottom left corner (in the (-X, -Y) quadrant of the local coordinate system of the MEMS object) with pixel # 1. Pixels increment first in the +X direction along the columns, and then in the +Y direction along the rows.
Each element in the MEMS device can be set to Angle 0, Angle 1, or Angle 2. The element, then, can be in state 0, 1, or 2.
The state of each element is set in the parameter columns. Parameter 10 controls elements 1 - 15. Parameter 11 controls elements 16 - 30, etc.
The "P-Flag" column controls the type of element. If P-Flag = 0, then the parameter 10 value will control rows 1 - 15. If P-Flag = 1, the parameter 10 value will control columns 1 - 15. If P-Flag = 2, the parameter 10 value will control individual pixels 1 - 15.
After the number of elements and the P-Flag values have been specified, the headings of the parameter columns will change. Parameter 10 will be labeled "Pixels 1-15." Parameter 11 will be labeled "Pixels 16-30," etc., until the total number of elements in the MEMS device is reached.
A single number is entered into each parameter column that specifies the state of each element.
To generate the number used to control the states of the elements, list the desired state for each element (0, 1, or 2). Then, treat that list as a number in base 3. Convert the number to base 10, and enter that value in the appropriate parameter column. In equation form:
value = (state of element 1) * 30 + (state of element 2) * 31 + (state of element 3) * 32 + (state of element 4) * 33 + .... + (state of element 15) * 314
For example, suppose that a MEMS device has 1 x 5 pixels. The P-Flag is set to 2, so that the individual pixels are addressed. Angle 0 = 0, Angle 1 = 5, and Angle 2 = -5, corresponding to states 0, 1, and 2.
The pixels are numbered starting from the -Y pixel, in this case. So the pixel numbers, from top to bottom, are:
( 5, 4, 3, 2, 1 )
Suppose we want the "top" pixels (in the +Y direction) to have tilts of +5, and the "bottom" pixels (in the –Y direction) to have tilts of -5. Then the tilt values are:
( +5, +5, 0, -5, -5) The state of the pixels will be: ( 1, 1, 0, 2, 2 )
Treat that list as a base-3 number to get:11022
Convert the number from base 3 to base 10:
110223 = (1 * 34) + (1 * 33) + (0 * 32) + (2 * 31) + (2 * 30)
= 11610
And enter the value 116 in the parameter 10 column (labeled "Pixels 1-15").
The pixels, starting from the +Y pixel and moving down, will then take on the angles
( +5, +5, 0, -5, -5).
Because of the way OpticStudio addresses the elements, the total number of addressable elements cannot exceed approximately 3750. If P-Flag = 0, the MEMS device is limited to 3750 rows. If P-Flag = 1, the MEMS device is limited to 3750 columns. If P-Flag = 2, the MEMS device is limited to 3750 pixels.
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