LCOS-SLM characteristics

Light utilization efficiency

Definition

Light utilization efficiency is defined as the ratio of the average reflected light intensity (Iave) to the incident light intensity (Ipow) when an LCOS-SLM is driven with a supply voltage ranging from 1 V to the maximum voltage (Vhigh).

Light utilization efficiency = Iave / Ipow [%]

Measurement method

Using a phase modulation optical system as shown in the figure where the polarization direction of the incident light is aligned with the orientation of the liquid crystal molecules, the reflected light intensity is measured at each supply voltage ranging from 1 V to the maximum voltage which is divided into 128 points. The incident angle (θ) is set within 10 degrees and the aperture size is set to 6 mm in diameter.

Measurement setup for light utilization efficiency

Measurement setup for light utilization efficiency

Measurement results

The table below shows the average light utilization efficiency for each of our LCOS-SLM types. Two or more light sources were used for measurement by the wide wavelength band type. The specific wavelength type delivers a high light utilization efficiency that exceeds 95 % and the wide wavelength band type offers 76 % to 86 %. The light loss is mainly caused by generation of diffracted light resulting from the pixel structure, scattering light in the liquid crystal layer, and absorption by the transparent electrode.

Evaluation results for light utilization efficiency (average values)

Type No.

Wide wavelength band type

Specific wavelength type

-01

-07

-08

-02

-03B

-05

-12

-13

-15

-16

-19

Wavelength of light source (nm)

633

1064

1550

785

1064

405

940

532

1550

532

1950

Light utilization efficiency (%)

76

80

86

97

97

97

97

97

97

97

97

Type No.

High-power laser type

Laser metal processing type

-02L/-02R

-03BL/-03BR

-12L/-12R

-15L/-15R

-16L/-16R

-19L/-19R

-03CL/-03CR

Wavelength of light source (nm)

785

1064

940

1550

532

1950

1064

Light utilization efficiency (%)

97

97 97 97 97 97 97

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